Messages in this thread | | | Date | Mon, 9 Oct 2006 01:50:26 +0200 | From | "Jesper Juhl" <> | Subject | Re: sluggish system responsiveness under higher IO load |
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On 08/10/06, Jens Axboe <jens.axboe@oracle.com> wrote: > On Sun, Oct 08 2006, Christian wrote: > > Am Freitag, 6. Oktober 2006 17:58 schrieb Paolo Ornati: > > > On Sun, 13 Aug 2006 18:15:12 +0200 > > > > > > Matthias Dahl <mlkernel@mortal-soul.de> wrote: > > > > Just let me know once you got them, so I can safely delete them again. > > > > > > > > At the moment, I am trying without preemption but for example doing a > > > > untar kernel sources still results in sluggish system responsiveness. :-( > > > > > > I used to have this type of problem and 2.6.19-rc1 looks much better > > > than 2.6.18. > > > > > > I'm using CONFIG_PREEMPT + CONFIG_PREEMPT_BKL, CFQ i/o scheduler > > > and /proc/sys/vm/swappiness = 20. > > > > > > Which change in the new kernel has made it better? I was following the lkml > > very close and didn't see any change that could have fixed that problem. > > There is a substantial CFQ update, so it could be that. Or it could be > something unrelated of course, I didn't check if eg the cpu scheduler > changed much. Or vm :-) > > -- > Jens Axboe > I want to chime in here and let you know that I've experienced something similar.
I'm using CFQ as my default I/O schedular. Since 2.6.18-git<something_I'm_not_sure_of> I've experienced that when doing heavy (or even not so heave) disk I/O my system gets very sluggish. Observable by the fact that my mouse pointer in X "jumps" which it never did before, and switching windows I can see the new window repaint slowly whereas earlier it would just snap onto the screen.
<serious hand-waving enabled> This is quite unreliable, but I *seem* to have observed a slightly higher overall memory use for my system since 2.6.18+ as well as the software interrupt rate (as observable by 'top' oscilating between 1.5 & 5 % with 2.6.18+ where with older kernels it would seem to mostly stay below 1%. I've also observed that when rebooting, unmounting my local filesystems takes significantly longer (previously just a second or two, recently up to a minute or not at all, that is, the system just hangs) - may or may not be related to this. <serious hand-waving disabled>
In any case, disk I/O seems to have a large negative impact on system performance recently compared to pre-2.6.18* kernels.
-- Jesper Juhl <jesper.juhl@gmail.com> Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please http://www.expita.com/nomime.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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