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Month: April 2009

Links for 2009-04-30

Published April 30, 2009

Links for 2009-04-29

Published April 29, 2009

Links for 2009-04-25

Published April 25, 2009

Links for 2009-04-24

Published April 24, 2009

Links for 2009-04-22

Published April 22, 2009

Links for 2009-04-21

Published April 21, 2009

Links for 2009-04-20

Published April 20, 2009

Links for 2009-04-17

Published April 17, 2009

Reminder: Irish computing history talk next Monday

Published April 17, 2009

Don’t forget — next Monday, the Heritage Society of Engineers Ireland, in association with The Irish Computer Society, and the ICT and Electronic and Electrical Divisions of Engineers Ireland, will be hosting an evening lecture entitled “Reminiscences of Early days of Computing in Ireland”, by Gordon Clarke (M.A., CEng., F.B.C.S., C.I.T.P., F.I.C.S). Sounds like it’ll be great. More details.

Update: it starts at 8pm; useful info! Also, the event’s flyer can be found on this page, which notes:

For those new to using our webcast facility, please see www.engineersireland.ie/webcast for information on how to set-up and access our webcasts. To view the event, please log onto the url below: https://engineersireland.webex.com/engineersireland/onstage/g.php?t=a&d=841959965 The password: computer

Links for 2009-04-16

Published April 16, 2009

Linux per-process I/O performance: measuring the wrong thing

Published April 15, 2009

A while back, I linkblogged about “iotop”, a very useful top-like UNIX utility to show which processes are initiating the most I/O bandwidth.

Teodor Milkov left a comment which is well worth noting, though:

Definitely iotop is a step in the right direction.

Unfortunately it’s still hard to tell who’s wasting most disk IO in too many situations.

Suppose you have two processes – dd and mysqld.

dd is doing massive linear IO and its throughput is 10MB/s. Let’s say dd reads from a slow USB drive and it’s limited to 10MB/s because of the slow reads from the USB.

At the same time MySQL is doing a lot of very small but random IO. A modern SATA 7200 rpm disk drive is only capable of about 90 IO operations per second (IOPS).

So ultimately most of the disk time would be occupied by the mysqld. Still iotop would show dd as the bigger IO user.

He goes into more detail on his blog. Fundamentally, iotop works based on what the Linux kernel offers for per-process I/O accounting, which is I/O bandwidth per second, not I/O operations per second. Most contemporary storage in desktops and low-end server equipment is IOPS-bound (‘A modern 7200 rpm SATA drive is only capable of about 90 IOPS’). Good point! Here’s hoping a future change to the Linux per-process I/O API allows measurement of IOPS as well…

Links for 2009-04-14

Published April 14, 2009

Big table desking

Published April 14, 2009

We have an extremely open-plan layout in work — no partitions, just long benches of keyboards and monitors. It looks a bit like this, but with less designer furniture and more Office Depot:

Aman pointed out that this is a new trend in workplace design, which Workalicious calls “Big Table Desking”:

I’m still not sure what to make of the frequent instances of Big Table Desking. While this kind of workstation arrangement is no doubt a new trend, the no-privacy work place is a throwback to the 1950s office pool, a line up of identical desks classroom style. Is it the peer to peer seating position that overcomes this? How would it? By building community? As opposed the pilot and passenger 747, catholic church model of everybody facing “forward”. Does the Big Table Desk break down this heirarchy by facing people towards one another, sharing a big desk instead of staking out territory? Is the big table desk a microcosm, a representation of a healthy organizational structure?

No comment ;)

It seems to be popular with designers, presumably due to their collaborative working needs.

Mind you, it also looks a bit like a Taylorist workplace layout from 1904, of which Wired says:

American engineer Frederick Taylor was obsessed with efficiency and oversight and is credited as one of the first people to actually design an office space. Taylor crowded workers together in a completely open environment while bosses looked on from private offices, much like on a factory floor.

YouBloom plug

Published April 14, 2009

Last week I got a very nice mail looking to plug a new music site:

‘I’m not sure if this would interest you at all but wanted to pass on the link to a new website called YouBloom.

It’s a new social networking and e-commerce website set up with independent artists in mind – to help them to make make real money (unlike MySpace etc which just make money from the artists)! It was set up by Irish Musician Phil Harrington and is backed by Sir Bob Geldof.

Admittedly I am involved with the website. I have been helping bring artists on site for the last few months, since I was introduced to the concept by a friend, but would love for you to take a look at the site anyway – even if it turns out to be of no interest to you.’

I normally wouldn’t post these, but I’m a sucker for flattery ;) and the poster had taken the time to read my blog a little. It also looks like the site allows bands to offer free MP3 downloads of their tunes, which IMO is a key factor for bands trying to get promotion.

UPC.ie’s new Channel 4 frequency for MythTV

Published April 12, 2009

So, after spending an hour or two attempting to figure out where the hell UPC had moved Channel 4 to, I eventually found out that it was now being broadcast on 543 Mhz. I also found out that this wasn’t part of the standard list of A1 to A30 channels in the “pal-ireland” range. :(

Thankfully, I then found this Frequency to MythTV channel converter page; here’s the correct values to use on the MythWeb channels page:

  • Freqid = 30
  • Finetune = -4

Links for 2009-04-10

Published April 10, 2009

Links for 2009-04-08

Published April 8, 2009

Links for 2009-04-07

Published April 7, 2009

Links for 2009-04-06

Published April 6, 2009

“you are, in fact, in the message queue business”

Published April 6, 2009

Oh man, this Twitter Ruby-vs-Scala language spat is hilarious; talk about handbags at dawn. I loved this exchange in the comments to this post in particular:

BJ Clark:

I’m mostly surprised that a guy who wrote the book on Scala comes out and says that Scala is better than everything else and someone actually listened and took him seriously. He has a vested interest in saying that Scala is the next big thing and I’ve yet to see any evidence that Kestrel is better (at anything) than RabbitMQ.

And frankly, I still get fail whales at Twitter on a daily basis, so, what exactly are they so proud about over there?

Steve Jenson:

Kestrel pages queues to disk: if you get more messages than you have memory, it’s fine. If RabbitMQ gets more messages than memory, it crashes. We talked to them extensively about this problem and they’re going to address it. We were hoping we’d be able to use RabbitMQ or another message queue. We didn’t want to be in the message queue business. At this point, given that we know the code and it’s performance inside and out, it makes sense to continue using and developing it.

BJ Clark:

I don’t feel like arguing with you but your logic isn’t clear to me. It would make sense that if you don’t want to be in the message queue business, you’d submit patches against an established message queue to make it work in your situation instead of writing your own message queue, twice. This is overlooking the fact that twitter is basically a massive message queue and you are, in fact, in the message queue business.

Zing!

Links for 2009-04-05

Published April 5, 2009

URL shortening services: my experience

Published April 5, 2009

A good post from Joshua Schachter about URL shortening services.

For what it’s worth, I ran into the unwanted-interstitial risk. At one stage, before I’d bothered registering jmason.org, sitescooper.taint.org or my other domains, I used a URL-shortening service to provide a memorable, short URL for an open-source application I wrote — http://zap.to/snarfnews/.

At some point a few years down the line, the forwarding process started accreting ads; eventually they became soft-porn in content, and I was forced to apologise to users for the forwarding I could no longer control!

By now, 10 years down the line, it seems to hijack the page entirely, returning a page in Cyrillic I can’t even read :( (apparently it’s a page of Flash games; thanks, Alexandr Ciornii, for the interpretation!)

Anyway, lesson learned.

Links for 2009-04-03

Published April 3, 2009

“Report Says Deal”

Published April 3, 2009

Twitter has this “Trending Topics” sidebar now, which lists the following topics:

Trending Topics

  • TGIF
  • National Cleavage
  • G20
  • Easter
  • #grammarsongs
  • France
  • #rp09
  • French
  • Grand National
  • Report Says Deal

Now, I’m not going to go into the topic of National Cleavage right now. ‘Report Says Deal’ is intriguing because it makes no sense, until you click through to see:

Real-time results for “Report Says Deal”

  1. Too_cool_normal dlloydsecret Google to Buy Twitter? Report Says Deal is in the Works http://bit.ly/Wt1Wb half a minute ago from twitterfeed    
  2. Orig_8102_003_normal dlloydthemlmpro Google to Buy Twitter? Report Says Deal is in the Works http://bit.ly/Wt1Wb 1 minute ago from twitterfeed    
  3. Ad-tech-paul2_normal techupdates [PCWrld] Google to Buy Twitter? Report Says Deal is in the Works http://tinyurl.com/c63ont 3 minutes ago from twitterfeed    
  4. Orkut_normal icidade Google to Buy Twitter? Report Says Deal is in the Works. http://is.gd/quu9 4 minutes ago from TweetDeck    
  5. Img00315_normal chrisgraves Retweeting @CinWomenBlogger: Retweeting @ays: Google to Buy Twitter? Report Says Deal is in the Works – PC World http://bitly.com/LhT4 6 minutes ago from twhirl

So I’d say that Twitter’s “Trending Topics” uses N-grams of between 1 and 3 “words” for topic identification. In this case, rather than “Report Says Deal“, a better topic string would be something like:

Google to Buy Twitter? Report Says Deal is in the Works – PC World

or even:

Google to Buy Twitter? Report Says Deal is in the Works – PC World http://bitly.com/LhT4

Funnily enough this is exactly the issue I ran into while developing this algorithm. The trick at this point is to apply a variant of the BLAST pattern-discovery algorithm, expanding the patterns sideways while they still match the same subsets of the corpus until they’re maximal.

Twitter folks, if you can read Perl, “assemble_regexps()” in seek-phrases-in-log in SpamAssassin SVN does this pretty nicely, and reasonably efficiently, and is licensed under the ASL 2.0. ;)

Links for 2009-04-02

Published April 2, 2009

Links for 2009-04-01

Published April 1, 2009