Messages in this thread | | | Date | Tue, 12 Oct 2004 22:44:31 +0200 | From | "Prakash K. Cheemplavam" <> | Subject | Re: CFQ v2 high cpu load fix(?) |
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Nick Piggin schrieb: > Jens Axboe wrote: > >> On Tue, Oct 12 2004, Nick Piggin wrote: >> >>> Ronny V. Vindenes wrote: >>> >>>> >>>> --- patches/linux-2.6.9-rc4-ck1/drivers/block/ll_rw_blk.c >>>> 2004-10-12 12:25:09.798003278 +0200 >>>> +++ linux-2.6.9-rc4-ck1/drivers/block/ll_rw_blk.c 2004-10-12 >>>> 12:25:42.959479479 +0200 >>>> @@ -100,7 +100,7 @@ >>>> nr = q->nr_requests; >>>> q->nr_congestion_on = nr; >>>> >>>> - nr = q->nr_requests - (q->nr_requests / 8) - 1; >>>> + nr = q->nr_requests - (q->nr_requests / 8) - >>>> (q->nr_requests/16)- 1; >>>> if (nr < 1) >>>> nr = 1; >>>> q->nr_congestion_off = nr; >>> >>> >>> >>> I thought this first hunk looked like a good idea when Arjan sent the >>> patch. Can you check if it alone helps your problem? >> >> >> >> Yeah agree, it's a good idea to leave a bit of air between congestion on >> and off. Fully explains the cfq v2 excessive sys time for some >> workloads, which is extra nice. >> > > Cool. Can you queue up a patch for when -mm opens again, or shall I? > I can't imagine it should cause any problems but a bit of testing > would be wise.
Just as a feedback: I applied the first hunk of that patch to 2.6.9-rc4-ck1 and it really makes a difference. At first I thought the staircase scheduler was responsible for io starvation sometimes, but now this behaviour is gone. Very well!
Prakash [unhandled content-type:application/pgp-signature] | |