Thursday, November 22, 2007

Guess what OS Don Knuth runs?

Check out http://www-cs-faculty.stanford.edu/~knuth/news.html

In the section "Wanted: A Name For High-Tech Grief" Knuth states and I quote

"I myself have often cried out for help to colleagues who have generously made house calls, in order to unwedge my highly customized Linux system"

We've known it for a while, looking at the customized fvwm2 configuration on Knuth's website, but it's good to see it in writing.

Some of you must be thinking, he has problems with Linux? We'll look at the keywords -- highly customized. Can't do that with other operating systems without hitting yourself in the head a few times or hitting your head against something. You don't hit yourself because your stupid, you do, because you brought the product :-)

Hmmm.... Now, if we can get everyone who has directly or in-directly been benefited from Knuth's work to run Linux, that would be a wonderful starting place. Of-course regular users are more than welcome to adopt and customize Linux.

Linux is a Trademark of Linus Torvalds

Tuesday, November 06, 2007

FOSS.IN delegate registration is open



Register at http://foss.in/2007/register/delegates/

The fee structure has changed this year. Do read the details before registering. This year we have project days and the main conference

Saturday, November 03, 2007

Talk at VTU

I gave a talk on Introduction to Operating Systems via EDUSAT. The lecture was broadcast to several universities via satellite. I had no live audience, but it was fun to speak into a camera. The video has been stored/archived for students to see later.
Here's a link to the slides

New Code in the Linux Kernel

I got some new code included into the mainline linux 2.6.24-rc1 kernel

cgroupstats - Is an infrastructure to allow sending control group statistics to user space using taskstats/genetlink
cpu_acct - CPU accounting subsystem for control groups

Worked on some other miscellaneous stuff as well. Overall, 2.6.24 was an interesting merge cycle, lots of new stuff went it. Check it out! Please do report regressions

A Quick Estimate

I was trying to estimate how long it would take for a timer, measured in nano-seconds using 64 bits would take to roll over. Here's my quick estimate

It would take 2^64/10^9 seconds = 2^64/2^9*5^9

Approximating on all calculations

= 2^55/5^9

5^3 = 125 ~= 2^7
5^9 = 2^21

= 2^55/2^21

= 2^34 seconds

2^34 seconds = 2^34/86500 days ~= 2^34/80*2^10 = 2^24/2^6 days = 2^18 days

1 year = 365 days, 3 years ~= 2^10 days

That leaves us with 2^8 years * 3 years

= 256*3 years before the timer overflows

With a machine, usually one would expect at-least one reboot in 800 years, if so, we would be fine for a long time to come.

See I need no calculator :-)

Saturday, October 27, 2007

FOSS.IN list of talks announced

Check out http://foss.in/2007/shortlist.php

The list of talks looks really good and I know a lot of people presenting at FOSS.IN. I am co-presenting on one topic. I'd say this year FOSS.IN is going to rock, so make sure your there.

Monday, October 08, 2007

India vs Australia (quick analysis)

India won the T20 world cup and became champions! The 50-50 games seem to be a different playing ground for the Indian Team. Have you been wondering why India did not fair so well, so far. Here's a quick layman analysis

  1. India have not been batting first, in all the T20 matches we won, we batted first!
  2. The team has changed and so have the rules. Instead of a powerplay for 20 overs with catch in fielders around, T20 has restrictions for just 4 overs. This makes a big difference to players like Sehwag and Gambhir, who I think are more suited to the field being well spread out (survive longer)

Here's some advice for the Indian Team (given that Dhoni reads cricinfo, you never know if he might read this blog as well :-) )

  1. Convert the 50-50 match to a 20-20 match, by keeping wickets in hand till the 30th over
  2. While batting second, get Dhoni in at #3, followed by Yuvraj at #4
  3. Get Dravid to Open the batting while chasing
  4. Tendulkar should come 4/5 down while chasing (when there is a mandatory ball change)
  5. Don't ever get Yuvraj to Bowl :-)
  6. While bowling first, attack aggressively, even if it means that more runs will be conceded

Friday, October 05, 2007

Memory Ordering (Recommended Reading)

I just finished reading this wonderful report on memory ordering. I highly recommend reading it. If you have anything to do with multi-core, multi-processor, parallel programming, you'll find the paper very insightful.

Other good to read papers/articles on memory ordering from Paul Mckenney are
  1. C++ Data-Dependency Ordering. May 2007.
  2. Overview of Linux-Kernel Reference Counting. January 2007.
  3. A simple and efficient memory model for weakly ordered architectures. Makes case for weakly ordered primitives in programming languages. Updated May 2007.

Wednesday, September 26, 2007

Doing the simple things first

I've always been lost trying to understand and do the complex things. I just realized that I miss out on doing and enjoying the simple things in life. Note to self, remember this and change.

Tuesday, September 25, 2007

India are Twenty20 champs




No one expected it, but secretly hoped for it; and it has happened. India are twenty 20 world cup champions. Boy, has this been a good time for sports. For those of you who do indeed know that hockey is our national game, spare a moment for this picture as well


Spare some time and visit http://www.bharatiyahockey.org/ and http://www.indianhockey.com/.

Now shifting back to twenty20, India beat Pakistan twice and the second win won us the cup. Both matches were close, nail biting (warning: watch your hygiene) finishes. Surprisingly, India got extremely lucky and batted first in almost all their encounters which they won. The statistics show a remarkable quality, that has been missing before, this was a true team effort. Everybody chipped in; in the batting department, we had contributions from Gautham Gambhir, Virendra Sehwag, Robin Uttapa, Yuvraj Singh, M. S. Dhoni, Rohit Sharma (who incidentally is yet to be dismissed in this form of the game). Karthik was a weak spot in the team, but boy did he keep well in the game against South Africa. In the bowling department, R. P. Singh, Irfan Pathan, Harbhajan Singh and Sreesanth were the key contributors.

India's fielding has been quite good, thanks to the absence of Saurav Ganguly, V.V.S. Laxman and Munaf Patel.

I am sure Dhoni is thinking मै तो युहीं चाला था बिना जाने मंज़िल मगर लोग आते गये और कारवाँ बंता गया |

Well done, keep up the good work boys!

Friday, September 07, 2007

Kernel Summit Photos - taken by Evgeniy Polyakov


Peter Zijlstra, Ingo Molnar, Venki Pallipadi and Balbir Singh in discussion

More photos will follow, including the group photo. Meanwhile, there are other photos at Evgeniy Polyakov's gallery.

Thursday, September 06, 2007

Kernel summit day 1 updates

Gerrit has some wonderful updates in his blog Linux and Open Source. LWN.net subscribers can read the summit update at 2007 Kernel Summit article right away or wait for a week for it to be available to public.

Friday, August 31, 2007

Off to VM and Kernel Summit

I've been invited to the VM (Virtual Memory) Summit in Cambridge, U.K. I will also be attending the Kernel Summit which is being held along side LinuxConf Europe 2007. Hopefully, I'll have interesting notes and pictures when I am back.

Algorithms dictionary online

http://www.nist.gov/dads/terms.html is a wonderful dictionary of terms and concepts in Algorithms. It's a wonderful dictionary and the references are excellent. I wish they made the content available as a book or a PDF document.

Monday, August 20, 2007

Perl module for taskstats

Way back last year, we developed the taskstats and delay accounting interface for the Linux Kernel. There is now a CPAN module to extract the same information using perl (all our example programs are in C). It's called Linux::Taskstats::Read. It can read the binary dump of taskstats information and interpret it.

Here's the module

I hope to be able to write a python interface for taskstats as well and do it quickly. I am sure someones already done the work.

Ranking and Unranking permutations

I've been a big fan of Skiena's Algorithm Design Manual , I recently found my first edition of the book (although I own the third ed...