New Linux kernel patch gives huge performance improvement

David Heath
Sunday, 21 November 2010 00:01

Business IT - Open Source

Based on an idea from Linus Torvalds, Linux kernel developer Mike Galbraith has implemented a patch which offers a huge performance improvement for interactive tasks.

Unfortunately too late for the recently closed 2.6.37 kernel, this 2.6.38 - bound patch offers a huge performance increase; perhaps as much as 60 times faster in a mixed CPU-intensive and graphically-intensive scenario.  The testers produced these results when performing a large compile along with web browsing and other user-oriented tasks.

All this in just 233 lines of code.

The patch serves to create task groups for each TTY and thus improves desktop responsiveness, especially under heavy loads.  The feature will be enabled by default at boot, but is configured to be enabled or disabled on-the-fly.

Linus Torvalds responded to the patch "Yeah. And I have to say that I'm (very happily) surprised by just how small that patch really ends up being, and how it's not intrusive or ugly either.

"I'm also very happy with just what it does to interactive performance. Admittedly, my 'testcase' is really trivial (reading email in a web-browser, scrolling around a bit, while doing a 'make -j64' on the kernel at the same time), but it's a test-case that is very relevant for me. And it is a _huge_ improvement.

It's an improvement for things like smooth scrolling around, but what I found more interesting was how it seems to really make web pages load a lot faster. Maybe it shouldn't have been surprising, but I always associated that with network performance. But there's clearly enough of a CPU load when loading a new web page that if you have a load average of 50+ at the same time, you _will_ be starved for CPU in the loading process, and probably won't get all the http requests out quickly enough.

So I think this is firmly one of those 'real improvement' patches. Good job. Group scheduling goes from 'useful for some specific server loads' to 'that's a killer feature'."

Linux is slowly entering the corporate world at all levels.  It is running on just about every Top500 supercomputer and recent reports suggest it is present in over one third of businesses.

As an aside, it is very educational to view the interactive development process between the many kernel developers involved in this process.