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barry
Apprentice
Joined: 01 May 2002
Posts: 170
Location: UK
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 Posted: Sat Feb 01, 2003 11:09 pm Post subject: Bad kernel performance with X11 |
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I've tried installing various versions of Gentoo over time and I've noticed that X performance has never been as good as other distributions, especially noticiable when you drag windows. I've got an nvidia card, and I get this problem with the normal XFree86 driver and the nvidia one.
I assumed it was something to do with my compilation, but I've just tried booting Gentoo via my Debian kernel (using chroot to change to Gentoo), and the performance is fine, so I'm assuming this is a kernel issue.
Has anyone else seen this problem? I'm compiliing on an Athlon XP 1700 with the default compilation flags on the kernel, and I've tried a couple of different kernel versions without success. |
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idl
Retired Dev
Joined: 24 Dec 2002
Posts: 1728
Location: Nottingham, UK
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| Posted: Sun Feb 02, 2003 12:00 am Post subject: |
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there are a number of things you can do..
first off what nvidia driver version are you using? because the 4191 are very poor on 2D, its being worked on apparently. Secondly, are you using metacity? if so thats why your window dragging sucks..
you may also want to try the ck2 kernel 'emerge ck-sources' its very fast indeed!
also try some more aggresive CFLAGS, the flags I use are just out right mental and things fly along 
Also do a search for an Xfree 'nice' wraper, that helps aswell.
this may be a bit OTT but you could also try ReiserFS, i find it a lot faster than ext3.
Good Luck |
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NicholasDWolfwood
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Joined: 19 Jan 2003
Posts: 235
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| Posted: Sun Feb 02, 2003 12:34 am Post subject: |
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This is OT, but I have an Athlon XP 1700+ too.
What optimzations other than "-march=athlon-xp -O3 -pipe" can I do? I want to make it super fast (Not super, but you know what I mean, faster than it is now) |
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barry
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Joined: 01 May 2002
Posts: 170
Location: UK
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| Posted: Sun Feb 02, 2003 12:56 am Post subject: |
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It's not a problem with the nvidia drivers, as I get the same with both the XFree supplied and the proprietary ones.
What I've done is booted up Debian (2.4.18 kernel) and then immediately used chroot to start up KDE under Gentoo, so I'm still using the exact same environment as Gentoo normally. The only difference is the kernel (and a couple of processes like init that start before the chroot).
When I compile the kernel for Gentoo I don't mess around with the flags, and I've tried the vanilla and redhat sources too. The windows jerk a bit when moved, while when I run Gentoo via Debian they're fine. Debian's not really known for aggressive compilation or performance patching, so I wouldn't expect their kernel to be ultra-fast. |
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Malakin
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Joined: 14 Apr 2002
Posts: 1692
Location: Victoria BC Canada
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| Posted: Sun Feb 02, 2003 1:00 am Post subject: |
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mtrr can cause a slowdown, not sure if it would be this noticeable though. "cat /proc/mtrr" will show you if it's working and if not recompile your kernel with mtrr enabled.
| Quote: | | What I've done is booted up Debian (2.4.18 kernel) and then immediately used chroot to start up KDE under Gentoo, so I'm still using the exact same environment as Gentoo normally. The only difference is the kernel (and a couple of processes like init that start before the chroot). |
Good idea, that definitely cuts down on the possibilities ;) |
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barry
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Joined: 01 May 2002
Posts: 170
Location: UK
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| Posted: Sun Feb 02, 2003 2:04 am Post subject: |
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I've enabled MTTR and the contents of /proc/mtrr is the same under both kernels.
Is there anything in the Gentoo startup (or possibly lacking) that could cause it? In a chroot Gentoo environment there's no problem, but obviously in that case the startup is different. |
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noff
Guru
Joined: 11 Nov 2002
Posts: 388
Location: College Park, Maryland
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| Posted: Sun Feb 02, 2003 3:18 am Post subject: |
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| NicholasDWolfwood wrote: | This is OT, but I have an Athlon XP 1700+ too.
What optimzations other than "-march=athlon-xp -O3 -pipe" can I do? I want to make it super fast (Not super, but you know what I mean, faster than it is now) |
Search for Cflag central and there is a big thread which people list theirs. You can be a lot more agressive probably.
_________________
What Larry was saying is that if you make it too easy for programmers, then poor programmers will be able to do things best left to good programmers, and will inevitably do them poorly. Everyone will suffer in the long term as a result." - Tom Chance |
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Malakin
Veteran
Joined: 14 Apr 2002
Posts: 1692
Location: Victoria BC Canada
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| Posted: Sun Feb 02, 2003 7:34 pm Post subject: |
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| Quote: | | What optimzations other than "-march=athlon-xp -O3 -pipe" can I do? |
You can use -fomit-frame-pointer and -ffast-math. -fomit-frame-pointer can cause problems with certain ebuilds though. Both will show some measurable speedup on most larger ebuilds.
Note that some ebuilds strip certain flags when they're known to cause problems so just because you're enabling something doesn't mean it's actually being used, looking over xfree-4.2.1-r2 it appears to be just stripping -funroll-loops.
Extra optimizations over the ones you're already using are generally going to do very little though.
Lots of gcc bencharks listed here illustrate this point:
http://www.gnu.org/software/gcc/benchmarks/
If you're adventuresome you could try gcc's profile driven optimization.
http://gcc.gnu.org/news/profiledriven.html
Or use Intels compiler which is somtimes quite a bit faster then gcc (even on Athlons).
http://www.coyotegulch.com/reviews/intel_comp/intel_gcc_bench2.html |
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