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Linux Kernel Benchmarking: 2.4 vs. 2.6-test
frooyo pastes from kerneltrap: "Cliff White recently posted some re-AIM multiuser benchmark results comparing the stable 2.4.23-pre5 kernel against the 2.6.0-test5 and 2.6.0-test5-mm4 development kernels. In his conclusion he makes reference to earlier scheduler tests posted by Mark Wong saying, "Short summary: we mostly rock.""
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The SMP code (written by Linux developers by the way) is supposed to be kicked up a notch in the new kernel. That's what I've heard anyway. I'd love to see Linux being the best OS for multiple CPU scaling.
That will help everyone from the server market, to me when I save up enough for a two processor motherboard.
Slashdot Syndrome: the sudden, extreme urge to correct someone in order to validate one's self.
now i need another CPU to increase performance!
Go figure. An OS that gets faster with each version.
---
"how can the same street intersect with itself? i must be at the nexus of the universe!" - cosmo kramer
If you thought SCO was mad over 2.4, just wait until they make up evidence for the 2.6 kernel!
Trolling is a art,
It's only significantly faster if you have 8 processors.
Whereas it is 7% slower if you have one processor.
I suppose they'll have uniprocessor version which runs faster? Lots of people have uniprocessor pcs.
Hyperthreading doesn't really count.
I run 2.4.22 at work and 2.6.0-testX at home. The 2.6.0test(vanilla) series feel much more responsive, especially in X. I have not done any real benchmarks of my systems, but after working with 2.4 all day 2.6 seems to fly.
Just my observation
-the_crowbar
Have you read the Moderator Guidelines
Looks like that 1970's UNIX code really increases performance for SMP P-III's.
Now we can appriciate the forsite that our Unix fathers had when developing Xeon SMP code in the late 1970's.
"the general trend in the metric indicates everything has been improving, so I think we rock."
:o)
For some reason, the scheduling seems to get more and more choppy (in that i've noticed) with every iteration of 2.4.x kernel. Currently i'm on 2.4.22, and while i don't have any specific tests, numbers or statistics i'm noticing some issues.
Easiest way to reproduce it is to have the machine do something cpu intensive, such as mkisofs, cdrecord, bzip2 some huge file, cp anything large, installing (via aptitude) or even the "Reading Package Lists...." stage of apt-get update.
Oftentimes, the machine will become unresponsive for about 3 seconds at a time, then jolt back up to speed, then pause for 3, on and on. Even after the command line returns the prompt, or gkrellm's cpu and proc krells show that everything is all done, i will still see lag in responses from the kb, mouse, or whatnot off and on for about 10-15 seconds.
I've gone over my kernel config and tweaked a few things here and there but with no change. I can back down to a 2.4.18 kernel and it's not as bad. Going down to a 2.2.x kernel completely solves the problem, but of course will bring its own issues with some of my newer packages (such as gcc) and a few pieces of newer hardware.
A friend of mine and I have gone over this (on my machine and his) and he experiences a lot of the same issues i do.
Mind you, i'm not complaining. I'm very grateful to all the developers of the world that i even *have* a linux system to run. But this is something that makes me more excited about the kernel 2.6.x series. I haven't tried one out yet, but from what i've heard and read, it should be awesoe.
do() || do_not();
I agree that those things are issues, but they have nothing to do with Linux (the kernel). This is a new release of /the kernel/. You should only get excited about it if you care what kernel you're running. Most people don't, and they shouldn't (as long as the kernel supports all their hardware).
It's always a long day... 86400 doesn't fit into a short.
You actually READ the article?!? Man! You ARE a N00b!
"terrorism" and "pedophilia" are the root passwords to the Constitution
I'd love to see Linux being the best OS for multiple CPU scaling.
You do need a scalable OS to suport lots of processors, of course, but you also need hardware that scales too (clustering doesn't count). Example - SGI is using Linux with NUMAflex on the Altixes to cluster 64-processor system images, but that kind of hardware isn't commodity in any way, and isn't going to be anytime soon.
Anyway, Linux doesn't scale THAT well...as of 9/2000, SGI was using IRIX for a 1024-processor single-system-image supercomputer; I've heard they can go to 2048 now, but I don't have anything to back that up. Dunno about Solaris, but I imagine it's pretty scalable as well.
Facts do not cease to exist because they are ignored. - Aldous Huxley
Just becaues you can't see its use outside of a toy, doesn't mean everybody can't.
Linux IT Consulting and Domino Development in Michigan
Devphaeton, you hit the nail on the head about 2.6.0. Its main advantage over 2.4.x (for this luser anyway) is the smoother multitasking even on a uniprocessor system. I'm running a tweaked 2.6.0-test5 on my laptop, and jobs that would make 2.4.x unusable are barely detectable (from the standpoint of moving the mouse around, typing up slashdot articles, and the like).
:-)
Of course, the ACPI support and swsusp doesn't hurt either
DARL: So, um, hey. It looks like there's this new "too-pointe-six colonel" out on the market from those Lenn-ucks people. We own all that too, right?
SUIT: Well, sir, it's like this. Do you remember how the 2.4 kernel had all of those lines of code in them that are ours, even though they showed up in textbooks before most of our stuff existed?
DARL: Sure, but how does that help us with this new thing?
SUIT: Think about it. Most operating systems, according to my extensive research during years of never having looked at a computer before, contain the same code that they always did, plus a couple of lines of new comments and an extra variable or two that shows how much you're able to charge users for the new features. Just think about the Windows 95 and 98 thing. Perfect example there.
DARL: But...my mansion only has 93 windows. Where is this heading?
SUIT: *blinks* Errr...yeah. Well, it's all the same code, and even those sneaky Linux commies try to pull a fast one on us and put one of those different codes in there, we can always assert our ownership of these "opened sources" files that I just printed out. I asked this guy, you know, and he said that all of these sources are what's in Linux, and since I printed it on paper and stuff, I figure it must be a textbook. Since we own all the words that show up in textbooks, and this has a lot of words, I think we've found ourselves a new angle here.
DARL: Smithers, cry havoc and let slip the Lenn-ucks colonel lawsuit monkeys once more!
I do so hate having to correct you people. *sigh*
"Linux doesn't exist. Everyone knows Linux is an unlicensed version of Unix"- Kieren O'Shaughnessy
linux-2.6.0-test5 - 992.06 - Uni
linux-2.6.0-test5 - 1017.43 - Dual
linux-2.6.0-test5 - 5406.68 - Quad
Does this mean that you only gain 3.49% when adding a 2nd processor? Obviously I don't expect things to scale linear but 3%!? Am I missing something here? And then 81.65% for quad? I'm not trolling, I'm looking for someone to explain what I'm missing.
Of course, there is the possibility of trimming cycles from the process of switching contexts. Linux, though, already had that pretty low. That's why Linus is so resistant to shared-memory, shared-context threads: the cost of processes is so low that the benefits are small. However, some speed was gained in context switches.
Overall, though, more switching means slower performance, even though the user feels like the system is faster. It's not faster. It's actually slower. It's just more responsive.
Confused yet? :)
Linux IT Consulting and Domino Development in Michigan
I've tried the new kernel, and I got more responsiveness issues than improvements. But besides that (I might very well have misconfigured something), I'd like to point out that the kernel itself isn't all that matters: the new drivers that accompany it are just as much important. I noticed a significant increase in X's launch time as well as a whopping 250 FPS with glxgears to be compared to the 150 FPS I got with my 2.4.22 setup. This is probably due to major improvements that were brought to the drivers for my i830M chipset.
You are correct! The scheduler reacts different to different work loads. This is why the kernel developers try hard to test their changes under a number of different workloads. To top it off with, they attempt to target the benchmarks which behave like real-world work loads rather than contrived and unrealistic workloads. That's not to say that they don't test those too, however, they clearly direct more attention at real-world workloads and corrosponding result sets.
The 2.6x series kernels will be a big step up for just about everyone that seriously uses their computer. Significant realiability improvements as well as faster thoughput on disks, much, much higher scalability for SMP (hyperthreading and numa and even highly loaded uni-systems) systems, and much lower latencies, all at the same time. Granted, there are still some tests which may not be a win-win all the way around, however, almost everything in general is an improvement with hardly any detracters.
So, saying, "we mostly rock", really is a true statement!
a quad cpu more performant than 4 * single cpu?
Odd but not impossible.
For example, if in the single cpu config the processes are doing a lot of memory-cache missed then having 4 cpus (with 4 times more the amount cache) could reduce the number a cache misses and so could make the quad configuration more than 4 times faster.
The same reason could explain why 2 cpus are not faster than one: if 2 caches are not large enough and if the processes have a very bad locality then you may get as much cache misses with the dual cpu system than with the single cpu system.