Slashdot Mirror
Kernel Comparison: Web Serving On 2.4 And 2.6
An anonymous reader writes "Many improvements have been made in the Linux 2.6 kernel to favor enterprise applications. This article presents results from the IBM Linux Technology Center's Web serving testing efforts, comparing the Linux 2.4 and 2.6 kernels from various aspects. The highlights here are the key enhancements in the 2.6 kernel, the test methodologies, and the results of the tests themselves. Bottom line: the 2.6 kernel is much faster than 2.4 for serving Web pages, with no loss in reliability."
See, all that Unix code that IBM stole from SCO and inserted into the Linux kernel was worth it!
You were having problems with your current webservers? They can't serve pages fast enough? You'll have to spend $50,000 to upgrade so you can handle it? Put 2.6 on! You might be able to hold off that upgrade for 6-12 months, by which time that $50,000 will buy you much more computer than it will today (not to mention you could invest that money and have more by then).
What do you call a FREE PERFORMANCE UPGRADE? You call it good!
Besides, it doesn't matter if it needs a "little while to iron out." If you just blindly deploy new kernels on production servers with no testing, you deserve the flack that will come you way if you get bit by a bug.
Comment forecast: Bits of genius surrounded by a sea of mediocrity.
In the case of RH5.2, security. I hope you've been doing the furious quantity of patching necessary to keep that secure. If not, I'd seriously consider moving to Debian. You still have to secure it, but it's really easy to do.
The small performance boost, according to this paper, is large. Huge, much the same as the scalability boosts that came in as a result of the mindcraft benchmarks. However, they are for the most part improvements in SMP. There are also some "responsiveness" improvements in the scheduler.
Should you move to 2.6? Probably not. As far as I can tell the gains are on big iron, really really small iron, and the desktop. I'm sure as hell not moving off 2.4 any time soon.
Dave
I write a blog now, you should be afraid.
"O(1) scales well..."
No, really?
Isn't that just a function of having 5 times as many apache processes serving content?
The new linux kernel is great, but the reason the this particlular kernel results is better performance ("5 times better") is because the application framework it is testing is horrible.
All of the "enterprise" applications in this test have several performance cripling features in common: socket per thread connections, fundemental reliance on threads, and massive memory foot print. Apache has one thread/process (the diff is a stack) per connections. Java requires a sizable multiple of memory usage as most other application languages (C/C++ obviously, but also Perl, Python, and PHP). J2EE is an inherently thread driven programming framwork.
So yes, Linux 2.6 ameliorates the downsides of unnecessary use of threading. It makes thread creation and context switching even faster on the Linux platform.
And Yes, Linux 2.6 memory management is fundementally better. Reverse Page Table Entry mappings make finding victim pages better; and it is designed to avoid victimizing active pages better.
But could you all imagine if people were designing fundementally better application framworks? Event driven application architectures like TwistedPython and POE, or Event-thread hybrid systems like SEDA.
The performance stats given in that article are shit, complete utter shit. I know. In the proprietary world I work in, I code faster programs on the same Linux platform on a daily basis; orders of magnitude faster.
All the accomplishments of Linux 2.6 can be used for true performance programming. I plead with you all, stop using Threads until you know what they are good for. Stop using the stack to maintain your program state. Throw off the shackles and learn to program network servers.
-- I am not a fanatic, I am a true believer.