Messages in this thread |  | | Date | Wed, 10 Oct 2001 06:27:01 +0200 | From | Andrea Arcangeli <> | Subject | Re: 2.4.10-ac10-preempt lmbench output. |
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On Wed, Oct 10, 2001 at 12:02:13AM -0400, Robert Love wrote: > On Tue, 2001-10-09 at 23:57, Dieter Nützel wrote: > > Robert you are running a dual PIII system, right? > > Could that be the ground why you aren't see the hiccup with your nice preempt > > patch? Are you running ReiserFS or EXT2/3? > > No, I am on a single P3-733. I am using ext3. > > I have had reports from users on both UP and SMP systems that say audio > playback is undisturbed during heavy I/O with preempt-kernel patch. Of > course, I don't know their definition of undisturbed...but I would wager > it doesn't include 2-3s skips.
If it's purerly I/O even mainline that is missing the reschedule points shouldn't matter.
Infact the only thing that hurts during pure I/O (I mean not I/O from cache, I mean real I/O to disk) is the browse of the lru dirty lists in buffer.c and the vm lists (the latter are covered in latest 2.4). And just the preemptive patch cannot help there since they're both covered by locks and the explicit checks in the preemptive patch will get a result equal to the lowlatency approch.
If it's mixed I/O half from cache and half from disk, then the lack of reschedule points could be the culprit of course.
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