Search Results: "beh"

11 May 2010

Ian Wienand: A short tour of TERM

I'd wager probably more people today don't know what the TERM environment variable really does than do (yes, everyone who used to use ed over a 300-baud acoustic-coupler is laughing, but times have changed!). I recently got hit by what was, at the time, a strange bug. Consider the following trivial Python program, that uses curses and issues the "hide the cursor" command. 
$ cat curses.py
import curses
curses.initscr()
curses.curs_set(0)
curses.nocbreak()
curses.echo()
curses.endwin()
If you run it in your xterm or linux console, nothing should happen. But change your TERM to vt102 and it won't work: 
$ TERM=vt102 python ./test.py
Traceback (most recent call last):test-curses.py
  File "./test-curses.py", line 5, in <module>
    curses.curs_set(0)
_curses.error: curs_set() returned ERR
(obvious when you explicitly reset the term, no so obvious when some script is doing it behind your back -- as I can attest!) So, what really happened there? The curs_set man page gives us the first clue:
curs_set returns the previous cursor state, or ERR if the requested visibility is not supported.
How do we know if visibility is supported? For that, curses consults the terminfo library. This is a giant database streching back to the dawn of time that says what certain terminals are capable of, and how to get them to do whatever it is you want them to do. So the TERM environment variable tells the terminfo libraries what database to use (see /usr/share/terminfo/*) when reporting features to people who ask, such as ncurses. man 5 terminfo tells us:
cursor_invisible civis vi make cursor invisible
So curses is asking terminfo how to make the cursor invisible, and getting back "that's not possible here", and hence throwing our error. But how can a person tell if their current terminal supports this feature? infocmp will echo out the features and what escape codes are used to access them. So we can check easily: 
$ echo $TERM
xterm
$ infocmp   grep civis
					   bel=^G, blink=\E[5m, bold=\E[1m, cbt=\E[Z, civis=\E[?25l,
$ TERM=vt102 infocmp   grep civis
$
So we can now clearly see that the vt102 terminal doesn't support civis, and hence has no way to make the cursor invisible; hence the error code. If you're ever looking for a good read, check out the termcap/terminfo master file. The comments are like a little slice of the history of computing!

4 May 2010

Erich Schubert: Facebook tracking users via "like" function.

Facebook recently launched the "Like" function, which basically can be embedded into arbitrary web sites. Naively, it does two things:
  1. Provide a "Like" button for sharing the web site
  2. Show you how many other users like the web site
Sounds good, doesn't it?But now reconsider: even when you don't use the "Like" function, facebook is in fact notified of which web sites you visit!.Encouraging you to "share" content with friends is the hanger for this function. This is what makes web masters install it on their sites: they expect to get some extra traffic from your friends, so they just add it.But whether you like it or not, it basically allows Facebook to track your complete web viewing habits. And it's the target web site that opts in, not the user! Combined with all the personal information Facebook already has on you, this is a major privacy concern. Combining this information might even be illegal in some countries (but probably not in the US where Facebook lives, privacy unfortunately has a low role here).The best workaround currently is to blacklist Facebooks "Like" function using some kind of AdBlock, for example using this element filter: 
IFRAME[src^="http://www.facebook.com/plugins/like.php"]
But in general, we should try to make this kind of data aggregation illegal without explicit consent and force Facebook to make this an opt-in feature. Political work needed here ...P.S.: Make sure to check if your AdBlock actually blocks and not just hides. As far as I can tell, WebKit Adblock, including Chromes, only hide ads. Firefoxs AdblockPlus seems to be more powerful.P.P.S.: yes I've read the claim that Facebook doesn't track. No wait, all they basically said was that they are not going to announce at F8 they will be selling web surfing behaviour based ads to their customers. They actually did NOT state (or guarantee) they will NOT use data mining on this data. Just that you probably will not be able to buy eyeballs based on rules such as "has visited/liked disney.com" ...P.P.P.S.: I've been told that facebook.com/widgets/like.php also needs to be blocked, since some sites use this URI scheme. And of course, Privoxy and similar privacy-increasing proxies are a useful addition, too.

3 May 2010

Christian Perrier: Bug #580000

Time for our bi-monthly post... Salvo Tomaselli reported the Debian bug #580000 on Sunday May 2nd, against the kopete package. Bug #570000 was reported as of February 15th 2010. We're now behind our "10,000 bugs in 2 months" pace by two weeks, so this confirms the slowdown in Debian's bug report rate. I hope this doesn't confirm also the slowdown in Debian's development rate.

2 May 2010

Dominique Dumont: Improve config file upgrades Ep 01

Hello The GSoC project Krzysztof and I are working aims to facilitate configuration upgrade during package upgrades. Most of the cases, this upgrade should not require any input from the user, even if the user had previously customized his configuration file. Currently configuration upgrade may ask questions to the user which may be hard to answer for most non-technical users. For more details see PackageConfigUpgrade on Debian wiki. (If you are not familiar with upgrade issues, you might want to read this page.) At the 2 extremes of upgrade tools, we have: Each tool has its own advantages and drawbacks. On the plus side of diff3 tools : On the other hand, here are the issues with diff3 based tools: For more details on diff3 issues, see Benjamin Pierce s paper (thanks to David Lutterkort from Augeas for the info) On the other end of the spectrum, Config::Model pros are: But, Config::Model main problem is: diff3 tools is lackluster for users. While Config::Model puts too much strain on packagers because it requires configuration models where all parameters are defined and declared in the model. For fast evolving projects, this can be a huge recurrent task (been there, done that for Xorg) . (Well, this recurrent task is a problem until doc, implementation and config model can be extracted from a single meta-description But I digress, this may be a project for GSoC 2011 :-p ) So, this GSoC project (for 2010) aims to find a compromise between these 2 extreme cases. On Config::Model, I ve always had a drawer statement whenever I was asked why Config::Model does not handle unknown parameter:
a configuration file cannot be validated if an unknown parameter can t be distinguished from a user typo.
This stance is fine for casual user interaction on a stable system: an unknown parameter is most likely an error. And the user must be warned of his error as soon as possible. For a stable distro release, packagers should have the time to provide complete models, so basing upgrade on complete models should be possible (famous last words ?). On the other hand, a lot of configuration upgrades will be done on unstable systems where software evolve quite fast, where models will likely fall behind software evolutions. Another shorcoming of my drawer statement is that it assumes user interaction where erroneous input is more likely. In case of configuration upgrades, there should be no user interaction. And we can assume that the config file to be upgraded was used (and thus validated) by the old version of the software. So unknown parameters should be tolerated and managed as best as possible. Now, the big question is: how ? In all attempts I ve seen in managing upgrades that goes beyond diff3 tools, the configuration is stored as structured data. Sometimes this structure can be infered from the configuration file syntax (shell vars, INI files, YAML, XML), sometimes not (sshd config file). In the latter case, some structural knowledge must be built in the upgrade tool. Currently, Config::Model is designed to bring a complete description of the structure and semantics of a configuration file. This is perceived as bringing too much structural and semantic knowledge ( too semantic ). So the maintenance cost is perceived as too important. That may be right or wrong, but that does not matter. Perception is more important here. So, let s figure out a way to reduce the amount of work required to perform upgrades (you may want to read a little bit more on configuration model creation before going on ) One possibility would be to support configuration models that allow unknown leaves in nodes. Such a model would provide a kind of fallback leaf description. Something like: this parameter is unknown, let s assume it s a simple string value . Let s consider sshd_config example to see how such a behavior would pan out for some upgrade scenarios. sshd model is made of 2 main classes:
- Sshd
- SshdMatchElement The second one contains all parameters allowed in a Match class (in fact, Match parameter is the only one in sshd that defines a new hierarchical level. All other parameters are simple leaves). Now let s consider typical upgrade scenarios from old version (with old models) to a more modern version. Let s assume that the model is lagging behind and the model does not follow sshd evolutions. So Config::Model will face 3 upgrade cases (extracted from sshd config history):
  1. Unexpected parameter that are actually simple leaf parameters. E.g. introduction of ClientAliveInterval.
  2. Obsolete parameters that should be migrated. E.g KeepAlive is renamed into TCPKeepAlive
  3. New structural parameters (introduction of Match element)
So what would happen with a model allowing unknown parameters but lacking specific instructions for these upgrades:
  1. ClientAliveInterval value would be kept. :-)
  2. KeepAlive would be kept as is.TCPKeepAlive would also be kept. No migration is performed, but the configuration would be good. As long as sshd supports the old parameter, we re good. :-/
  3. Without knowledge of the structure brought by Match parameters, Config::Model would consider that parameter in Match block would duplicate parameters in the main block and remove the duplicate. User data may be lost. :-(
So, there s not silver bullet. Let s resume what we ve learnt: Next step is to figure out what would happen if the same strategy is applied to other types of configuration files. But that will be for another blog. All the best

29 April 2010

David Welton: Erlang vs node.js

I've written about Erlang in the past, and my suspicion that, soon or later, other languages/systems will come along and "eat its lunch". Scala is one such potential contender. Another that has been gaining some visiblity lately is node.js, a simple framework for creating networked applications on top of Google's V8 Javascript engine. I should define what Erlang's lunch is a little bit better before we go on. Erlang does several things really, really well; better than many existing, mainstream systems:
  1. Concurrency - the Actor model that it uses is much easier and more pleasant than dealing with threads.
  2. Distributed systems - Erlang makes this fairly easy and pleasant as well.
  3. Fault tolerant systems - using its distributed powers, Erlang is good for writing things like telephone switches that can't spend any significant time down.
Of these, I think the big one is concurrency. Distributed systems are nice, but not a critical point for most people. Same goes with fault-tollerant: those who need it really need it, but the rest of us are willing to make some compromises. Our web applications are important, but generally not something where people's lives hang in the balance. How does Erlang do "concurrency"? The developer creates Erlang "processes" that interact with one another by passing messages. These are not real, OS level processes, though, and this is critical to how Erlang operates. Since these processes must all coexist within one real, system level process, it is absolutely essential that no operation that they perform hangs the entire system! The Erlang runtime system is built around this concept. Any Erlang process can do things like read and write to the disk or network, or have a "while (true) .... " loop (it doesn't actually look quite like that in Erlang, but that's the idea), and it won't wedge the system. This knowledge is also critical when you want to interface Erlang to the outside world: if your C library contains a routine that might block for a long time, you can't just call it from Erlang as it won't be a well-behaved part of Erlang's world (there are ways around this of course, but make life a bit more complicated for the developer). All this is done with Erlang's scheduler: each Erlang process gets a number of operations it can run before some other process gets to run, so even our while loop will only run for a bit before the system moves on to something else. IO is rigorously done with non-blocking calls internally in order to keep that from becoming an issue. No other system that I know of has such a focus on being non-blocking, and node.js is no exception: a while(true) loop is perfectly capable of wedging the system. Node.js works by passing functions (closures, in many cases) around so that work can be performed as needs be. However, the actual functions that run actually do block the system, and thus must be written in order to not run for too long. Also, and this is important, Node.js also does its best to make IO non-blocking by default, so that you don't have to worry about IO calls. Node.js isn't up to the level Erlang is at, because it requires more manual intervention and thinking about how to do things, but it's probably "good enough" for many tasks. How often do you really write code with so many calculations that it slows things down? Not often in my case - the real world problem I most often encounter is IO, and node.js does its best to make that non-blocking, so that it can be handled in the "background" or a bit at a time, without wedging the system. And if you really needed to write a long-running calculation (say you want to stream the digits of PI or something), you can break up your calculation manually, which may not be quite as elegant as Erlang, but is "good enough" for many people. "Good enough" concurrency, combined with a language that is at least an order of magnitude more popular than Erlang, and a fast runtime, combined with ease of use in general (it's way easier to get started with node.js than with most Erlang web stuff) make for a system that's likely to do fairly well in terms of diffusion and popularity, and is going to "eat some of Erlang's lunch". Or perhaps, rather than actually taking users away from Erlang, it's likely to attract people that might have otherwise gone to Erlang.

27 April 2010

Matthew Garrett: Radeon reclocking

Alex released another set of Radeon power management patches over the weekend, and I've been adding my own code on top of that (Alex's patches go on top of drm-next, mine go on top of there). I've left it stress-testing for a couple of hours without it falling over, which tells me that it's stable enough that I can feel smug. This is a pleasing counterpoint to the previous experiences I've been having, which have been rife with a heady mixture of chip lockups or kernel deadlocks. It turns out that gpus are hard.

There's a few things you need to know about gpus. The first is that if they're discrete devices they typically have their own memory controller and video memory. The second is that there's an impressive number of ways that you can end up touching that memory. The third is that they tend to get upset if something tries to touch that memory and the memory controller is in the middle of reclocking at the time.

The first and most obvious use of video memory is by the gpu itself. Accelerated operations on radeon are carried out by sending a command packet to the command processor. This is achieved by sharing a ring buffer between the cpu and the gpu, with the gpu reading packets out of that ring buffer and performing the operations contained within them. Many of these operations will touch video memory (that being the nature of most things you want a gpu to do), and if that happens bad things occur. Like the card locking up and potentially taking your PCI bus with it.

So, obviously, we don't want that to happen. The first thing we do is take a mutex that blocks any further accelerated operations from being submitted by userspace. Then we wait until we get an interrupt from the gpu telling us that the display engine has gone idle. The problem here is that we don't have a terribly good idea of how many more operations there are to complete and we don't know how long each of those operations is going to take, but this is less bad than some of the alternatives[1]. Jerome Glisse has some ideas on how to improve this to require less waiting, but the effects should still be pretty much invisible to the average user.

So we've stopped the command processor touching ram. Everything's good, right?

Well, not really. The obvious problem is that users typically want to display something, so there's a separate chunk of chip that's repeatedly copying video memory over to your monitor. That's got to go too. Thankfully, there's a convenient bit in the crtc registers that lets us turn that off, but the pretty unsurprising downside is that your screen goes blank while that's happening. So we don't want to do that. Instead, we try to perform the reclock while there's nothing being displayed on the screen - that is, while we're in the screen region where a crt's electron gun would be scanning back from the bottom of the screen to the top. It turns out that rather a lot of display assumptions depend on this happening even if there's no crt, no electron gun and no thick sheet of glass with a decent approximation of vacuum behind it, so we get to do this even if we're displaying to an LVDS. And we have about 400-500 microseconds to do it - an almost generous amount of time.

So we ask the hardware to generate an interrupt when we enter vblank and then we reclock. Except the hardware has an irritating habit of lying - sometimes we get the interrupt a line or two before vblank, sometimes we get it after we've already gone out the other side. Vexing, and not entirely solved yet - so sometimes you'll still get a single blank frame during reclock. But there are plans, and they'll probably even work.

At this point the acceleration hardware isn't touching the memory and the scanout hardware isn't touching the memory. Except it still crashes under some workloads. This one took me longer to track down, but the answer turned out to be pretty straightforward. Not all operations are accelerated. When they're not accelerated they have to be done in software. That means that the CPU has to write to the video memory itself. I'm sure you can see where this is going. This was fixed without too much trouble once I'd finished picking through the driver to work out every location where objects might be mapped into the CPU's address space, at which point it's a simple matter of unmapping them and blocking the fault handler from remapping them until the reclock is finished. Linux, thankfully, has lots of synchronisation primitives. And now everything works.

Except when it doesn't. This took a final period of head scratching, followed by the discovery that ttm (the memory allocator used by radeon) has a background thread that would occasionally fire to clean up objects. And by clean up objects, I mean change their mapping - which means updating their status in the gart, which means touching video memory. So, let's block that. And that tripped me off to the fact that even if it couldn't submit new commands, the CPU could still create or destroy objects - with the same consequences.

So, once all of these are blocked, video memory is quiescent and we can do what we want. And we do, at least once I'd sorted out the bits where I was taking locks in the wrong order and deadlocking. Depending on the powerplay tables available on your card we'll chose different rates and so your power savings will vary heavily depending on the values that your vendor provided, but the card I'm testing on sees a handy 30W drop at idle. Right now we're only changing clocks and not dropping voltage so there's potentially a little more to come.

While getting this stable was pretty miserable, the documented entry points for clock changing made a lot of this easier than it would otherwise have been. It's also probably worth noting that Intel's clock configuration registers are entirely missing from any public documentation and the dirver Intel submitted to make them work in their latest chips appeared to have been deliberately obfuscated, so thanks to AMD for making all of this possible.

[1] It's possible to insert various command packets that either indicate when they've passed or stall until a register value gets updated, but these either cause awkward problems with the cp locking or mean that the gui idle functionality never goes idle, so they're not ideal either.

25 April 2010

Russell Coker: Links April 2010

Sam Harris gave an interesting TED talk about whether there are scientific answers to moral questions [1]. One of his insightful points was that when dealing with facts certain opinions should be excluded it would be good if journalists who report on issues of science could understand this. Another insight was that religious people most strongly agree with him regarding the issue of whether there are factual answers to moral questions but they think that God just handed the answers to their ancesters rather than making it an issue that requires consideration. He cites the issue of gay marriage as being a distraction from moral issues such as genocide and poverty. He asks how have we convinced ourself that every culture has a point of view worth considering? . He asks how the ignorance of the Taliban on the topic of physics is any less obvious than on the topic of human well-being. Dan Gilbert gave an insightful TED talk titled Why Are We Happy? [2]. One interesting fact he cites is that people who become paraplegic are no less happy in the long term than people who win the lottery. He points out that a shopping mall full of Zen monks is not going to be particularly profitable and uses this fact to explain the promotion of natural happiness over synthetic happiness in our society. Dan Barber gave an amusing and informative TED talk How I Fell in Love with a Fish [3]. He speaks about ecological fish farming and how the fish are more tasty as well as the farm being good for the environment. The farm in question is in the south-west of Spain, hopefully there will be more similar farms in other parts of the world soon. Gary Lauder gave an interesting brief TED talk about road signs [4]. His main point was to advocate a road sign saying take turns , but there are already signs in the US at freeway on-ramps saying that 1 or 2 cars may enter every time the light turns green which is a similar concept. The innovative thing he did was to estimate the amount of time and petrol wasted by stop signs, add that over a year based on the average income and then estimate that an annuity covering that ongoing expense would cost more than $2,000,000. This makes two stop signs at an intersection have an expense of $1,000,000 each. He suggests that rather than installing stop signs it would be cheaper to buy the adjacent land, chop down all trees, and then sell it again. Alan Siegel gave an insightful TED talk about simplifying legal documents [5]. He gives an example of an IRS document which was analysed with a Heat Map to show which parts confused the readers the IRS adopted a new document that his group designed which made it easier for taxpayers. He advocates legislation to make legal documents easier to understand for customers of financial services. Tim Berners Lee gave an interesting TED talk about Open Data, he illustrated it with some fantastic videos showing how mashups have been used with government data [6] and how the Open Street Map project developed over time. Martin F. Krafft gave an interesting Debconf talk about Tool Adoption Behavior in the Debian project [7]. One thing that I found particularly interesting was his description of the Delphi Method that he used to assemble a panel of experts and gather a consensus of opinion. The post-processing on this talk was very good, in some sections Martin s presentation notes are shown on screen with the video of him in the corner. As an aside, I think we really do need camera-phones. The Big Money has an interesting article comparing the Mafia Bust Out with the practices of US banks [8]. Mark Roth gave an exciting TED talk about using Hydrogen Sulphide to trigger suspended animation [9]. They are now doing human trials for suspending people who have serious injuries to reduce tissue damage during the process of surgery. Pawan Sinha gave an interesting TED talk about how brains learn to see [10]. He started by talking about curing blindness in people who have been blind since birth. But he then ended by showing some research into the correlation between visual processing and Autism, he showed that an Autistic child had significantly different visual patterns when playing Pong to an NT child. Adora Svitak gave an insightful TED talk about what adults can learn from kids [11]. She made some particularly interesting points about the education system requiring that adults respect children more and expect them to do better than their parents which is essential for all progress in society. The NY Times has an interesting article on animal homosexuality [12]. In terms of research it focusses on lesbian relationships between albatrosses. But a large part of the article is devoted to the politics of scientific research into animal sexuality. BrowserShots.org shows you what your web site looks like in different web browsers [13]. Cory Doctorow wrote an insightful article titles Can You Survive a Benevolent Dictatorship about the Apple DRM [14]. He describes the way the Apple Digital Restrictions Management (DRM) doesn t stop copyright violation but does reduce competition in the computer industry. He is not going to sell his work on the Apple store (for the iPad or iPhone etc) and suggests that customers should choose a more open platform. It s unfortunate that he didn t suggest a better platform.

24 April 2010

Russell Coker: Is the NBN a Good Idea

Since writing my post about whether the National Broadband Network can ever break even [1] I ve had a number of people try to convince me of it s merit. He is my summary and rebuttal of some of the arguments for the NBN: The FUD Claims are made that Australia may fall behind the rest of the world, children may be disadvantaged in their education, or many other bad things may unless a faster net access is provided to everyone. That is FUD. If we are going to spend $43,000,000,000 then we should have some evidence that it will do some good. One thing to note is that rural areas will not get anything near the 100Mb/s speeds that FTTH will deliver to people in the cities. So if faster net access is actually essential then it would probably make sense to start by delivering ADSL2+ speeds to rural areas something that is not planned to be part of the NBN. Some people claim that having slow net access (ADSL2+) is going to preclude unknown future uses of the Internet. However the NBN is only going to be 100MB/s so any such claim is essentially that unknown things will happen in the future to make 24Mb/s too slow, but those unknown things won t make 100Mb/s too slow . I started using computer networks when a 1200/75 modem was considered fast. Over about the last 25 years typical net access speeds have increased from 1200b/s to about 12Mb/s, that s a factor of 10,000 speed improvement! Now the people who believe that we only need to multiply the current speed by a factor of 4 to address all future needs could be correct, but it seems unlikely and doesn t seem like a good idea for a $43,000,000,000 bet. If they were talking about 1Gb/s net access then things would be different in this regard. Technological Development Some people compare the NBN to the Apollo Program and suggest that the scientific research involved in implementing a FTTH network might result in useful developments in other areas. The Wikipedia page about Fiber to the premises by country indicates that Hong Kong had 1Gb/s available in 2006. It seems that a service which is rolled out 4 years later and 10 times slower than in Hong Kong is not going to involve a huge amount of research. Certainly nothing like the Apollo Program. It would allow multiple HDTV channels to be viewed at the same time According to the Australian Bureau of Statistics in 2001 the average Australian household had 2.6 people (3.0 in NT) [2]. The incidence of every member of a household wanting to watch a different live TV channel at the same time is probably quite low, it seems that young people nowadays spend as much time watching Youtube as they do watching TV. Based on the Wikipedia bit-rate page it seems that an ADSL2+ link could stream two HDTV channels. I could use fiber speeds today There are some people who claim that they need faster speeds for their data transfers right now. The problem is that the latency of data transfer is a bottleneck in transfer rates. In some quick tests between servers that have reasonably fast connections to the Internet I was only able to get one international transfer in excess of ADSL2+ speed (24Mb/s or 3MB/s). I was able to transfer data between London and Germany at a speed of 11MB/s which was possibly limited by the 100baseT Ethernet connection in the data center in Germany. Now if the people who pay for that German server were to pay more then they would get a higher speed. So anyone who downloads anything from my web site in it s current configuration would get a significant performance boost by using an NBN connection if they live in Europe! But if they live in Australia then they will probably get a fraction of that speed (a quick test indicates that my ADSL2+ connection gives me about 500KB/s from my web server. I need to have at least three transfers going at the same time to get more than 600KB/s when downloading files from other countries, and it s rare to have a single download run at a speed higher than 100KB/s. It would be handy if I could download at higher speeds from my ISP s mirror (which seems to be the only way someone in Australia can even use full ADSL2+ speeds). But it s certainly not worth the $5,000 per household installation cost of the NBN to get that. I m sure that there are some people who really do have usage patterns that could take advantage of fiber net access, one possibility would be downloading large files from a local source such as a major web site that uses a CDN. It seems likely to me that the majority of people who fit this category are using major porn services. Fiber would be good for Video-Conferencing To be better than ADSL for video-conferencing a NBN connection would need a faster upload speed. Internode is already selling NBN connections for the trial areas [3]. The cheapest fiber plans that they offer are at the 50/2 speed, that s 50Mb/s download and 2Mb/s upload in theory ADSL2+ should have a higher upload speed. In my tests the best result I ve got from sending files over my ADSL2+ link to another country is about 110KB/s (880Kb/s). The fact that the theoretical speed of a fiber connection is better than the measured speed of an ADSL2+ connection in this regard doesn t mean much, let s not assume that a fiber connection will get it s theoretical maximum speed. Not that you necessarily need higher speeds for video-conferencing, Youtube is one of many services that uses a lot less bandwidth than the upload speed of an ADSL2+ connection. Also video-calls which are supported on most 3G mobile phones use even less bandwidth again. I want an NBN connection to run a server at home The fastest connection for uploading that Internode offers to home users is the Home High plan at 100/8 speed, that is maybe a bit more than twice as fast for uploading as ADSL2+. They also offer a SOHO plan that supports 16Mb/s upload speed (at extra expense) and suggest that customers who want higher speeds contact their business sales department. But they include both sending and receiving data in the bandwidth quota for the fiber connections. Transmitting data at 16Mb/s isn t that great for a server. The cheapest virtual server plan on offer from Linode [4] includes 200GB of data transfer per month and has significantly higher transmission speeds. You could get a Linode virtual server plus an Internode ADSL2+ connection for about the same price as an Internode fiber connection to the home. There are two down-sides to virtual servers, one is that they are limited in the amount of RAM that they have (I can easily afford to buy 8G of RAM for a home system but renting an 8G virtual server is going to be expensive) and the other is that the storage is limited. Shared storage on virtual servers can be slow and is limited in size. If you need to run a server with a few terabytes of data storage (which is cheap on commodity SATA disks but expensive on server-grade disks) and you don t need to transfer much of it then a home server on the NBN might do well. Otherwise it s probably not going to work well for server use. The NBN will avoid people leaving their PC on to do downloads and save electricity To save electricity you would have to have a significant incidence of situations where a download can complete fast enough over the NBN to allow the user to turn their PC off before going to bed but be slow enough over ADSL to require that it be left on overnight. That would probably only apply to downloads from a CDN or from a local ISP mirror. From the Internode mirror I can download a test file at a speed of 850KB/s (I guess this means that my ADSL connection is not delivering full speed I suspect poor quality wiring in my home and would try to fix it if the current speed was too slow). In 5 minutes spend brushing my teeth I could download 250M of data, in the same time if I had a 100/4 connection on the NBN I might be able to download almost 3G of data. So in the unlikely event that I wanted to download a CD or DVD image and turn off my PC immediately before going to bed then the NBN would be a good thing. But then of course I would want to burn the CD or DVD image to disc and that would take long enough that I would leave it on overnight My ADSL connection gives really low speeds or I m out of range for ADSL Some people who live only a short distance from an exchange are unable to get ADSL2+. Some people live a long way from exchanges and are outside ADSL range. The ideal solution to these problems is not to provide fiber access to the majority of the population, it is to provide ADSL to everyone who is near an exchange and maybe provide fiber access to some people who are a long way from exchanges. I find it rather ironic that some people in the country are essentially saying because net access in the country is so slow we need fiber in the cities . The NBN is not going to give fiber to rural areas, satellite is one of the options that will be used. Really High Speeds I have been informed that to get the distances needed for the NBN they have to use Single Mode Fiber, this permits scaling up to higher speeds at some later time by changing the hardware at the end points. So we could end up with a Hong Kong speed network at some future time with the same fibers. This is a good thing. But I don t think that we need to get fiber installed right now so that we can use 100Mb, we could wait until there is enough need to get the faster transmission rates from the start. At the moment it s just a waste of money.

23 April 2010

Joachim Breitner: Making dictionary passting explicit in Haskell

Haskell provides type classes to support polymorphism. A type class defines a few methods, which can then be implemented for a concrete type in the type class instance. This is a powerful system, but it also has it drawbacks. Most notably, each type can have at most one implementation of the type class. But sometimes you need to use a different implementation. If, for example, you used the Binary class to store data on disk. Now you changed your data type and the binary instance, and you can not read the old data any more. One solution is to re-name your type using newtype and implement another type instance for that. Often, this is enough. But still, instances are not first-class-citizens. You can not pass them around or modify them, as you can pass around and modify data and functions. Under the hood of the compiler, things look different. The ghc puts the methods of the instance in a dictionary and passes that implicitly to any functions having a (Class a) constraint. (Other implementations exist though) If one could make that behavior explicit, one could easily modify the instance before passing it to the function. But this is unfortunately not possible. But it is possible to pass an explicit dictionary along the data. I use the Monoid class as an example, and define a representation of the dictionary to-be-passed, as well as the dictionary of the default instance: 
data MonoidDict a = MonoidDict
    ed_mempty :: a
  , ed_mappend :: a -> a -> a
   
monoidDict :: Monoid a => MonoidDict a
monoidDict = MonoidDict mempty mappend
(For conciseness, I ignore the mconcat method.) My first idea was to pass this instance along with data: (MonoidDict a, a). But this would not work because there are methods, such as mempty, who need the dictionary without getting passed a value to use. Therefore, I need to put the dictionary both in the covariant and the contravariant position: 
newtype WithMonoidDict a = WithMonoidDict (MonoidDict a -> (MonoidDict a, a))
We need functions to clamp a dictionary to a value, and to extract it again: 
wrapWithCustomMonoidDict :: MonoidDict a -> a -> WithMonoidDict a
wrapWithCustomMonoidDict dict val = WithMonoidDict $ const (dict, val)
extractFromCustomMonoidDict :: MonoidDict a -> WithMonoidDict a -> a
extractFromCustomMonoidDict dict (WithMonoidDict f) = snd (f dict)
Note that both expect the dictionary, so that it can be fed into WithMonoidDict from both sides . For convenience, we can define variants that use the standard instance: 
wrapWithMonoidDict :: Monoid a => a -> WithMonoidDict a
wrapWithMonoidDict = wrapWithCustomMonoidDict monoidDict
extractFromMonoidDict :: Monoid a => WithMonoidDict a -> a
extractFromMonoidDict = extractFromCustomMonoidDict monoidDict
We want to be able to pass the wrapped values as any other value with a Monoid instance, so we need to declare that: 
instance Monoid (WithMonoidDict a) where
  mempty = WithMonoidDict (\d -> (d, ed_mempty d))
  mappend (WithMonoidDict f1) (WithMonoidDict f2) = WithMonoidDict $ \d ->
  let (d1,v1) = f1 d
  (d2,v2) = f2 d
  in  (d1, ed_mappend d1 v1 v2)
Note that mappend has the choice between three dictionaries This is not a good sign, but let s hope that they are all the same. Does it work? Let s see: 
listInstance :: MonoidDict [a]
listInstance = monoidDict
reverseInstance :: MonoidDict [a]
reverseInstance = monoidDict   ed_mappend = \l1 l2 -> l2 ++ l1  
examples = do
  let l1 = [1,2,3]
  let l2 = [4,5,6]
  putStrLn $ "Example lists: " ++ show l1 ++ " " ++ show l2
  putStrLn $ "l1 ++ l2: " ++ show (l1 ++ l2) 
  putStrLn $ "l1  mappend  l2: " ++ show (l1  mappend  l2) 
  putStrLn $ "Wrapped with default instance:"
  putStrLn $ "l1  mappend  l2: " ++ show (
  extractFromMonoidDict $ wrapWithMonoidDict l1  mappend  wrapWithMonoidDict l2)
  putStrLn $ "Same with reversed monoid instance:"
  putStrLn $ "l1  mappend  l2: " ++ show (
  extractFromCustomMonoidDict reverseInstance $
  wrapWithCustomMonoidDict reverseInstance l1  mappend 
  wrapWithCustomMonoidDict reverseInstance l2)
Running examples gives this output: 
Example lists: [1,2,3] [4,5,6]
l1 ++ l2: [1,2,3,4,5,6]
l1  mappend  l2: [1,2,3,4,5,6]
Wrapped with default instance:
l1  mappend  l2: [1,2,3,4,5,6]
Same with reversed monoid instance:
l1  mappend  l2: [4,5,6,1,2,3]
Indeed it works. Unfortunately, this approach is not sufficient for all cases. It is perfectly valid to have functions with signature (Monoid a => Int -> Int). Obviously, this function would have no access to the explicit dictionary, because no value of type a is passed to or from it.<monoid a="a"> I wonder if it would be possible to extend the syntax somehow to be able to properly pass an alternative dictionary to such functions. But given that not all compilers use dictionary passing, my hopes are low.

Joachim Breitner: Making dictionary passing explicit in Haskell

Haskell provides type classes to support polymorphism. A type class defines a few methods, which can then be implemented for a concrete type in the type class instance. This is a powerful system, but it also has it drawbacks. Most notably, each type can have at most one implementation of the type class. But sometimes you need to use a different implementation. If, for example, you used the Binary class to store data on disk. Now you changed your data type and the binary instance, and you can not read the old data any more. One solution is to re-name your type using newtype and implement another type instance for that. Often, this is enough. But still, instances are not first-class-citizens. You can not pass them around or modify them, as you can pass around and modify data and functions. Under the hood of the compiler, things look different. The ghc puts the methods of the instance in a dictionary and passes that implicitly to any functions having a (Class a) constraint. (Other implementations exist though) If one could make that behavior explicit, one could easily modify the instance before passing it to the function. But this is unfortunately not possible. But it is possible to pass an explicit dictionary along the data. I use the Monoid class as an example, and define a representation of the dictionary to-be-passed, as well as the dictionary of the default instance: 
data MonoidDict a = MonoidDict
    ed_mempty :: a
  , ed_mappend :: a -> a -> a
   
monoidDict :: Monoid a => MonoidDict a
monoidDict = MonoidDict mempty mappend
(For conciseness, I ignore the mconcat method.) My first idea was to pass this instance along with data: (MonoidDict a, a). But this would not work because there are methods, such as mempty, who need the dictionary without getting passed a value to use. Therefore, I need to put the dictionary both in the covariant and the contravariant position: 
newtype WithMonoidDict a = WithMonoidDict (MonoidDict a -> (MonoidDict a, a))
We need functions to clamp a dictionary to a value, and to extract it again: 
wrapWithCustomMonoidDict :: MonoidDict a -> a -> WithMonoidDict a
wrapWithCustomMonoidDict dict val = WithMonoidDict $ const (dict, val)
extractFromCustomMonoidDict :: MonoidDict a -> WithMonoidDict a -> a
extractFromCustomMonoidDict dict (WithMonoidDict f) = snd (f dict)
Note that both expect the dictionary, so that it can be fed into WithMonoidDict from both sides . For convenience, we can define variants that use the standard instance: 
wrapWithMonoidDict :: Monoid a => a -> WithMonoidDict a
wrapWithMonoidDict = wrapWithCustomMonoidDict monoidDict
extractFromMonoidDict :: Monoid a => WithMonoidDict a -> a
extractFromMonoidDict = extractFromCustomMonoidDict monoidDict
We want to be able to pass the wrapped values as any other value with a Monoid instance, so we need to declare that: 
instance Monoid (WithMonoidDict a) where
  mempty = WithMonoidDict (\d -> (d, ed_mempty d))
  mappend (WithMonoidDict f1) (WithMonoidDict f2) = WithMonoidDict $ \d ->
  let (d1,v1) = f1 d
  (d2,v2) = f2 d
  in  (d1, ed_mappend d1 v1 v2)
Note that mappend has the choice between three dictionaries This is not a good sign, but let s hope that they are all the same. Does it work? Let s see: 
listInstance :: MonoidDict [a]
listInstance = monoidDict
reverseInstance :: MonoidDict [a]
reverseInstance = monoidDict   ed_mappend = \l1 l2 -> l2 ++ l1  
examples = do
  let l1 = [1,2,3]
  let l2 = [4,5,6]
  putStrLn $ "Example lists: " ++ show l1 ++ " " ++ show l2
  putStrLn $ "l1 ++ l2: " ++ show (l1 ++ l2) 
  putStrLn $ "l1  mappend  l2: " ++ show (l1  mappend  l2) 
  putStrLn $ "Wrapped with default instance:"
  putStrLn $ "l1  mappend  l2: " ++ show (
  extractFromMonoidDict $ wrapWithMonoidDict l1  mappend  wrapWithMonoidDict l2)
  putStrLn $ "Same with reversed monoid instance:"
  putStrLn $ "l1  mappend  l2: " ++ show (
  extractFromCustomMonoidDict reverseInstance $
  wrapWithCustomMonoidDict reverseInstance l1  mappend 
  wrapWithCustomMonoidDict reverseInstance l2)
Running examples gives this output: 
Example lists: [1,2,3] [4,5,6]
l1 ++ l2: [1,2,3,4,5,6]
l1  mappend  l2: [1,2,3,4,5,6]
Wrapped with default instance:
l1  mappend  l2: [1,2,3,4,5,6]
Same with reversed monoid instance:
l1  mappend  l2: [4,5,6,1,2,3]
Indeed it works. Unfortunately, this approach is not sufficient for all cases. It is perfectly valid to have a function with signature (Monoid a => Maybe a -> Maybe a), whose behavior depends on the instance of a, even when being passed Nothing and returning Nothing. Such a function woul<monoid a="a">d have a problem here, because the dictionary would not be passed to the function.
</monoid> I wonder if it would be possible to extend the Haskell language somehow to be able to properly pass an alternative dictionary to such functions. But given that not all compilers use dictionary passing, my hopes are low.

22 April 2010

Matthew Garrett: Looks like I picked the wrong week to give up crystal meth

One of the features of Windows 7 is that hitting windows+p will pop up a little dialog that allows you to configure your active display outputs. This is an improvement over previous versions of Windows, which would generally instead have a variety of random vendor-specific tools that would function differently, look ugly and make you cry. So, hurrah to Windows for moving into the 21st century.

Most laptops have a display switch key. This is sent in a variety of ways, generally either via the keyboard controller, via WMI or via ACPI. In Linux we take all of these events and turn them into KEY_SWITCHVIDEOMODE, making it easy to implement standardised behaviour.

This is, obviously, far too straight forward.

Microsoft, rather than introducing an input mechanism that allows all of these events to hook into the windows+p infrastructure, provide the following recommendation:

As documented in this Launchpad bug, vendors are starting to do this. It's been seen in HP and Dell machines, at least, and it's presumably going to become more widespread.

So, if your display switch button now just makes the letter "P" appear, say thanks to Microsoft. There's a range of ways we can fix this, although none of them are straightforward and those of you who currently use left-Windows-p as a keyboard shortcut are going to be sad. I would say that I feel your pain, but my current plan is to spend the immediate future getting drunk enough that I stop caring.

(The good news is that the same set of recommendations says that you can no longer put a Windows sticker on a monitor unless it has a valid and accurate EDID. The bad news is that that implies that you've previously been able to put a Windows sticker on a monitor without it having a valid and accurate EDID)

20 April 2010

Biella Coleman: On Internet Punditry and Engendering Change

One day a very well known Internet theorist writes a rant on women. The rant generates controversy, controversy lands theorist on WYNC on the media , despite the fact the he does not really work on the politics of gender. If this is so, why then give him more air time and focus on the NPR show? There are three lessons that precipitate from this social fact that are worth highlighting: 1.The fact that NPR chose him to pontificate and not a woman nullifies Shirky s thesis that behavior is one of the most important factors in keeping women behind, unless of course NPR asked a bunch of women but they were too meek to be on the air (not likely). If they wanted to keep the star power that is Shirky, the very least they could have done is had a woman respond. The solutions to get more women in the limelight are so easy to implement but they do require some thoughtfulness and foresight. 2.So what I am saying, it is about networks and Shirky, isn t he a theorist of networks and behavior? It seems to be to more controversial, he really did not address how important networks are for the politics of visibility, instead he focused on individual behavior. If famous highly networked folks, most of them men, don t highlight women in their blog posts, their twitter feeds, and don t invite them to conferences, it is going to make very little difffernce whether a woman is meek or confident. So if there are more guys that are visible, which is certainly the case, it is as much their job to help engender change, not so much by pontificating but acting. 3. I realized that though I first thought his rant was a reflection of his personality (at least his public persona, I am sure he is a nice guy), in fact the rant is valuable to an anthropologist interested in digital media because it is an auto-ethnographic snapshot of web 2.0 punditry culture. It often comes across as smarmy and snarky, which is due in part, to how difficult it is to get your message heard in the sea of many voices. Just like there is an aesthetic of audaciousness in a lot of Internet memeology, for example, the pundits too must often act in extreme ways to get attention which might inf fact be one of the reasons why they are reluctant to share the stage once they have worked hard to get there.

Biella Coleman: On Internet Punditry and Engendering Change

One day a very well known Internet theorist writes a rant on women. The rant generates controversy, controversy lands theorist on WYNC on the media , despite the fact the he does not really work on the politics of gender. If this is so, why then give him more air time and focus on the NPR show? There are three lessons that precipitate from this social fact that are worth highlighting: 1.The fact that NPR chose him to pontificate and not a woman nullifies Shirky s thesis that behavior is one of the most important factors in keeping women behind, unless of course NPR asked a bunch of women but they were too meek to be on the air (not likely). If they wanted to keep the star power that is Shirky, the very least they could have done is had a woman respond. The solutions to get more women in the limelight are so easy to implement but they do require some thoughtfulness and foresight. 2.So what I am saying, it is about networks and Shirky, isn t he a theorist of networks and behavior? It seems to be to more controversial, he really did not address how important networks are for the politics of visibility, instead he focused on individual behavior. If famous highly networked folks, most of them men, don t highlight women in their blog posts, their twitter feeds, and don t invite them to conferences, it is going to make very little difffernce whether a woman is meek or confident. So if there are more guys that are visible, which is certainly the case, it is as much their job to help engender change, not so much by pontificating but acting. 3. I realized that though I first thought his rant was a reflection of his personality (at least his public persona, I am sure he is a nice guy), in fact the rant is valuable to an anthropologist interested in digital media because it is an auto-ethnographic snapshot of web 2.0 punditry culture. It often comes across as smarmy and snarky, which is due in part, to how difficult it is to get your message heard in the sea of many voices. Just like there is an aesthetic of audaciousness in a lot of Internet memeology, for example, the pundits too must often act in extreme ways to get attention which might inf fact be one of the reasons why they are reluctant to share the stage once they have worked hard to get there.

Matt Zimmerman: Lucid ruminations

A few months ago, I wrote about changes in our development process for Ubuntu 10.04 LTS in order to meet our goals for this long-term release. So, how has it turned out? Well, the development teams are still very busy preparing for the upcoming release, so there hasn t been too much time for retrospection yet. Here are some of my initial thoughts, though. A more complete set of retrospectives on Lucid should give us some good ideas for how to improve further in Maverick and beyond. Update: Fixed broken link.

Adrian von Bidder: Google and the Linux Kernel Community

The Android developers seem to feel that they have been singled out for a level of criticism which few other embedded vendors including those demonstrating much worse community behavior have to deal with.
This is from Jonathan Corbet's coverage of the Collaboration Summit and matches my impression. I guess what some Google folks don't necessarily see is that they work for a company that has a big sign outside that effectively says we are not Microsoft or Apple or Sony or the RIAA/MPAA (implied: we're the good guys.) If you put up such a sign, and then disappoint people's expectations, you got to live with the consequences. (Google's marketing was once more successful with their recent actions in China. Get lots of good press coverage, get rid of quite a few critics, and pull out of a market where you didn't make big money in any case.)

15 April 2010

MJ Ray: Debian Project Leader Election Campaign Round-up

I ve been AWOL for most of the debian project leader election campaigns this year, but I still want to vote, so I ve been dredging the emails on the last day. Maybe someone still has to vote and reads this, or maybe it ll help someone to interpret the result. What I ve done this year is to make a quick tally of platform points and campaign answers that I liked and disliked for each candidate, then total them up to get an order. If anyone gets a negative (more dislikes than likes), then I ll rank them below NOTA. Platforms: Margarita Manterola, Stefano Zacchiroli, Wouter Verhelst, Charles Plessy. Some of the questions: Make of that what you will. It surprised me which way the scores came out, but there was one answer with such a massive problem (in my opinion) that I ranked its giver equal with the next candidate down anyway. If you re a debian developer (DD), have you voted yet?

13 April 2010

Gunnar Wolf: Regarding the fatal cycling accident in Ciudad Universitaria

My blog is written in English, even though I sometimes post content relevant locally. Anyway, I want this to be as widely known as possible. We are about to launch a website/community for my University's cyclists, BiciUNAMonos. Please note the site I'm linking is still very preliminary in several ways. But that's the least relevant for now. I am translating here a message written by fellow cyclist (and researcher in the Institute of Astronomy of my University) Sergio Mendoza.
Regarding the fatal cycling accident in Ciudad Universitaria Yesterday night I got home, and was quite surprised to open my mailbox and find a considerable amount of messages under the subject Urgent: Fallen cyclist! I immediately noticed something was very wrong, and was surprised they were contacting me. When I decided to read the first such message, I realized what happened: Dr. Jorge Villanueva was run over by the Puma [internal University service] bus number 14, route 2, which was being driven over the speed limit. This happened last Sunday, April 11. On Sundays, all of Ciudad Universitaria becomes a cycling and running circuit. I was immediately brought back to the moment that, when I was leaving my office in the Astronomy Institute and heading towards Cerro del Agua avenue, a lady driving over the speed limit on the circuit that comes from Metro Universidad threw her car at me. I saw her at a few centimeters distance from her windshield... To the day I don't know how I pulled my bike away, as I was going to hit the windshield with my shoulder. Everything happened in slow motion, I just heard several cars honking at this imprudent lady. I didn't have a scratch, but got excessively close to getting a strong hit, and with the adrenaline raging I gave a kind caress with my closed fist to her brand new car. I had to free my adrenaline somehow... My legs were trembling when I tried to pedal. I told her, lady, I am excessively visible in my bike, why did you do this? , she didn't answer, she just looked despectively at me. This kind of accidents happen every day in the University and its main entries. Precisely today, a University professor threw his car at me entering the University via Cerro del Agua. When I reached him and confronted him, he told me completely sure of his words that I was invading the lane with my bike, and that it was my fault. Anybody would have thought a car-driving university professor is capable of reading the Metropolitant Transit Regulations that clearly states on its 1st article: The priority for using the public space, for the different transport modes will be according to the following priorization: I. Pedestrians; II. Cyclists; III. Users and providers of massive, collective or individual public transport service; IV. users of particular automotor transport; and V. users and providers of freight transport. We are now organizing to put up the first ghost bike in Ciudad Universitaria. This happens few days before the formal inauguration of BiciUNAMonos, the universitary association of urban cyclists; we will do this remembering our university mate. I see every day more people in the University hitting their bike pedals to get to their faculties, centers and research institutes, but what is striking is the lack of University infrastructure. The few cycleways we have are built to use a bycicle system that is open only until 16:00. It is good, but it is in no way useful for those of us who use the bike every day and at every hour, no matter the weather. The main problem lies at the communication points, when cyclists arrive from outside Ciudad Universitaria and have to take the regular circuits to reach the cycleways. The Transit Regulation, in the 1st article I quoted above, defines in an excellent way the priorities that must exist to allow human movility. In this regard we have to mention that:
  1. The pedestrians must be enormously protected with walkways and semaphores to allow them to safely walk. In Ciudad Unviersitaria there are many places that don't even have a walkway or semaphores, and drivers do not respect the pedestrian's preference. Also, now in the central area of Ciudad Universitaria we have the Pumabus system on a confined lane, providing an excellent service to the pedestrians to move within the campus.
  2. The cyclist comes next in this priorization, but there is nothing obvious for him. There are a couple of cyclist ways, usually invaded by pedestrians, and explicitly made to use the Bicipuma system. Cyclists need their own lane for circulation in the Universitary circuit; pedestrians have walkways, Pumab s has its confined lanes, but the cyclists still lack it. The third lane that remains is precisely for the IV and V entries in the Metropolitan Transport Regulations. They can perfectly share the remaining lane in the campus.
The last thing I wanted was to formally announce BiciUNAMonos reminding a fallen cyclist and dedicating a ghost bycicle to his memory in Ciudad Universtiaria, but we don't have a choice. We have to make it very clear to the University community that the bicycle is the best transport system, and that the drivers' imprudence inside Ciudad Universitaria must be strongly punished. Sergio Mendoza
President
http://www.biciunamonos.org
Coincidentally, today I also had a freightening experience. Taking one of my usual routes to work, going up from the sporting area in the Western half of the campus (just before where the map lists the highest point in my ride), just by Investigaciones Biom dicas, I heard a car hitting the breaks behind me and passing me (on my right side) quite narrowly. I was, as always, driving towards the center of the lane, to be able to respond to unforseen events (as this one, precisely). The Universitary authorities had the great(?) idea of placing round, small bumps before the Pumabus stations to avoid drivers parking in front of them. I have seen a strong accident caused by them, and was close to suffering one myself some months ago. I know that just after Biom dicas there are some such bumps, so I never ride too much to the right I don't know what was on this driver's head. Ciudad Universitaria has a 40 Km/h speed limit. Yes, it might seem too low - Circuits are wide and well planned. But there is a lot of cyclist and pedestrian transit, at all times, and I must recognize such a limit is well in place. I often take a longer route to my Institute, bordering the University along Av. Delf n Madrigal. People tell me I'm crazy, as this is an avenue that's often taken at high speed - Usually, cars pass me by between 60 and 80 Km/h. However, I even feel safer going that way than going inside the University. Contrary to the popular belief, Universitary people do not have better driving habits than the bulk of the population. And it's often much easier to drive along a way where the traffic even if it goes at three times my speed runs only in one direction, unlike the swarming of people going in every possible direction inside the main campus. Anyway, last Sunday we lost a University professor, we lost a cyclist. Some people lost a friend, a family member. We have to make this case well known, we have to speak with the authorities so they see the Bicipuma system is good, but not enough. Cycling is the only way to go for a city as complex as ours. A much needed first step is to allow proper vial connections linking the University and the many avenues that surround it. Another one is to make a campaign so the cyclists are not seen as Sergio regards as intruders in the streets The street belongs to us all. Cyclists should never drive on walkways or among pedestrians. Drivers need to learn to share the streets with us.

11 April 2010

Christian Perrier: [life] Paris marathon 2010~bubulle-1 ACCEPTED

Upload accepted by organisers. Upload time has been 3h49'29" (my watch says 27", eh!). That was a good one, really (actually, I can compare to only 3 as it was my fourth marathon after Paris and Cologne 2009, plus the unofficial Rambouillet Forest marathon I ran alone 6 weeks after Paris 2009). For marathoners around, here are the chronometric data. Please note that GPS watches tend to overestimate the distance, mostly because of the jerky way one runs in mass events, as well as geometric considerations related to the imprecision of GPS (imprecision may be lateral and thus the line recorded by the watch is often less straight than the real one). For instance, according to my watch, Paris marathon was 42.63km long, so an overestimate by nearly 500meters. As a consequence, the recorded speed of 5'23"/km should be corrected to 5'25". So, times below should be increased by 2 seconds. As a conclusion, even though I can improve the pace and avoid going too fast in the first 25km, I'm very happy as I avoided nearly collapsing as I did last year (with sometimes over 7'00/km and a few walks). Going back home was OK and I had no cramps and I still haven't any. This is also what one gets when preparing well. My only regret is that I didn't run over 30km since, indeed, Cologne Marathon! That made the difference in the last 12 kilometers, obviously. Having spent the winter on many half-marathons (either alone, or a few officials) clearly improved my "performance" up to 25km. For the next marathon (a marathoner always thinks about the next one), I need to have 1 or 2 long trainings a few weeks before. Now, I have to find out which one will be the next one... and I wish good luck to my friend No l K the, who is preparing the Mainz marathon for May 9th as well as Dirk who's certainly preparing another one. Guys, rendez-vous is of course for Debconf10 in NYC. We won't run a marathon for sur, but how about an half one? :-)

9 April 2010

David Welton: US Exports: "The Cloud"?

An Economist special report in last week's print edition talks about how the US will need focus more on savings and exports:

A special report on America's economy: Time to rebalance I've been thinking about that for a while too, especially after the dollar's recent weakness, although it has been strengthening some, lately, apparently due to the state of Greece's finances... I think that the computing industry is, in general, well poised to take advantage of that. For instance, what could be easier to export than computing power or "Software as a Service"? All it takes is a few minutes for someone in Europe to sign up to a US-based service with a credit card. For instance, compare Linode's prices and good service with most of their European competitors (gandi.net for instance, who are good people, and you have to love that they put "no bullshit" right on their front page). Not that they don't have good service in Europe, but it's very difficult to compete on price with the dollar being significantly cheaper. With the dollar where it is right now, gandi is almost, but not quite, competitive with Linode. If you don't include taxes. If the dollar weakens again, though, things could easily tilt far in Linode's favor. Besides a weak dollar, I think it will be important for companies in a position to do so in the US to focus on "the rest of the world". The US is a big, populous country where it's very easy to forget about far-off lands. Compare my home town of Eugene, Oregon to where I live in Padova. Google Maps says that it takes 7+ hours to drive to Vancouver, Canada (which, to tell the truth, isn't all that foreign in that they speak English with an accent much closer to mine than say, Alabama or Maine). Going south, Google says it's 15+ hours just to San Diego, although I think that's optimistic myself, given traffic in California. From Padova, I can be in France in 5 hours, according to Google, 3 hours to Switzerland, 4 to Innsbruck, in Austria, less than 3 hours to the capital of Slovenia, Ljubljana, and around 3 hours to Croatia, too. And if you wanted to throw in another country, the Republic of San Marino is also less than 3 hours away, according to Google's driving time estimates. You could probably live your entire life in a place like Eugene and never really deal much with foreigners, whereas here, nearby borders are both a historic and an ever-present fact. The outcome of this is that, to some degree, people in the US have traditionally focused their businesses "inwards" until they got to a certain size. Which is, of course, a natural thing to do when you have such a big, homogenous market to deal with before you even start thinking about foreign languages, different laws, exchange rates and all the hassle those things entail. However, if exchange rates hold steady or favor the US further, and internal spending remains weaker, it appears as if it may be sensible for companies to invest some time and energy to attract clients in "the rest of the world". "Cloud" (anyone got a better term? this one's awfully vague, but I want to encompass both "computing power" like Linode or Amazon's EC2, as well as "software as a service") companies likely will have a much easier time of things: for many services, it's easy to just keep running things in the US for a while, and worry about having physical or legal infrastructure abroad later. Your service might not be quite as snappy as it may be with a local server, but it'll do, if it performs a useful function. Compare that with a more traditional business where you might have to do something like open a factory abroad, or at the very least figure out the details of how to ship physical products abroad and sell them, and do so in a way that you're somewhat insured against the large array of things that could go wrong between sending your products on their merry way, and someone buying them in Oslo, Lisbon or Prague. Since this barrier to entry is lower, it makes more sense to climb over it earlier on. As an example, Linode recently did a deal to provide VPS services from a London data center, to make their service more attractive to European customers. However, they still don't appear have marketing materials translated into various languages, and presumably they don't have support staff capable of speaking languages like Chinese, German or Russian either (well, at least not in an official capacity). This isn't to pick on them; they may have considered those things and found them too much of an expense/distraction/hassle for the time being - they certainly know their business better than I do - and that they simply are content to make do with English. Other businesses, however, may decide that a local touch is important to attracting clients. What do you need to look at to make your service more attractive to people in other countries? In no particular order:

There's certainly no lack of work there, but on the other hand, it's possible to do almost all of it from wherever you happen to be located, rather than spending lots of money and time flying around to remote corners of the globe, as is still common practice in many industries.

7 April 2010

Patrick Schoenfeld: Ubuntu considering critical bugs an "invalid" bug?

I just discovered that bug report over at Ubuntu.
Short summary:
They have a script in upstart which is not meant to be run manually and if you do it will erase your whole file system. Additionally it seems that the fact that you shall not run that script is not communicated anywhere.

That alone isn't the most spectacular about it. Bugs happen. Whats spectacular about it is how a Canonical employee and member of the TechBoard (for people who don't know it: The people who decide about the technical direction Ubuntu takes) handles that bug. One quote of him to reflect it all:
Sorry, the only response here is "Don't Do That Then"

So what we have here is a classical case of bad programming. The problem in question is that the script expects a certain environment variable to be set. Fair enough. However it does not check if its set at all and instead of failing or using a sensible default it simply sticks to undefined behaviour. What we have here is a classical programming mistake every beginner tends to do. People who start programming often forget (or don't know) that every external value we rely on must be considered untrustworthy. Therefore a good practice is to check those values.In this case someone decided that this is useless because they suffer from the wrong assumption that nobody ever calls it manually and the other wrong assumption that caller of the scriptwill always set the environment variable correctly. This is a double-fail.
Now the developer in question does not accept that (someone else indicated why the behaviour of the script is dangerous), he simply says that the bug is invalid. Thats really a pity.

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