Use io_schedule() instead schedule()
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From: Rik van Riel on 14 Dec 2009 09:40 On 12/14/2009 07:30 AM, KOSAKI Motohiro wrote: > All task sleeping point in vmscan (e.g. congestion_wait) use > io_schedule. then shrink_zone_begin use it too. I'm not sure we really are in io wait when waiting on this queue, but there's a fair chance we may be so this is a reasonable change. > Signed-off-by: KOSAKI Motohiro<kosaki.motohiro(a)jp.fujitsu.com> Acked-by: Rik van Riel <riel(a)redhat.com> -- All rights reversed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Minchan Kim on 14 Dec 2009 19:00 On Mon, 14 Dec 2009 21:30:54 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> wrote: > All task sleeping point in vmscan (e.g. congestion_wait) use > io_schedule. then shrink_zone_begin use it too. > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> > --- > mm/vmscan.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 3562a2d..0880668 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1624,7 +1624,7 @@ static int shrink_zone_begin(struct zone *zone, struct scan_control *sc) > max_zone_concurrent_reclaimers) > break; > > - schedule(); > + io_schedule(); Hmm. We have many cond_resched which is not io_schedule in vmscan.c. In addition, if system doesn't have swap device space and out of page cache due to heavy memory pressue, VM might scan & drop pages until priority is zero or zone is unreclaimable. I think it would be not a IO wait. > > /* > * If other processes freed enough memory while we waited, > -- > 1.6.5.2 > > > -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: KOSAKI Motohiro on 14 Dec 2009 20:00 > On Mon, 14 Dec 2009 21:30:54 +0900 (JST) > KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> wrote: > > > All task sleeping point in vmscan (e.g. congestion_wait) use > > io_schedule. then shrink_zone_begin use it too. > > > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> > > --- > > mm/vmscan.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 3562a2d..0880668 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1624,7 +1624,7 @@ static int shrink_zone_begin(struct zone *zone, struct scan_control *sc) > > max_zone_concurrent_reclaimers) > > break; > > > > - schedule(); > > + io_schedule(); > > Hmm. We have many cond_resched which is not io_schedule in vmscan.c. cond_resched don't mean sleep on wait queue. it's similar to yield. > In addition, if system doesn't have swap device space and out of page cache > due to heavy memory pressue, VM might scan & drop pages until priority is zero > or zone is unreclaimable. > > I think it would be not a IO wait. two point. 1. For long time, Administrator usually watch iowait% at heavy memory pressure. I don't hope change this without reasonable reason. 2. iowait makes scheduler bonus a bit, vmscan task should have many time slice than memory consume task. it improve VM stabilization. but I agree the benefit isn't so big. if we have reasonable reason, I don't oppose use schedule(). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Minchan Kim on 14 Dec 2009 20:20
On Tue, Dec 15, 2009 at 9:56 AM, KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> wrote: >> On Mon, 14 Dec 2009 21:30:54 +0900 (JST) >> KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> wrote: >> >> > All task sleeping point in vmscan (e.g. congestion_wait) use >> > io_schedule. then shrink_zone_begin use it too. >> > >> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> >> > --- >> > mm/vmscan.c | 2 +- >> > 1 files changed, 1 insertions(+), 1 deletions(-) >> > >> > diff --git a/mm/vmscan.c b/mm/vmscan.c >> > index 3562a2d..0880668 100644 >> > --- a/mm/vmscan.c >> > +++ b/mm/vmscan.c >> > @@ -1624,7 +1624,7 @@ static int shrink_zone_begin(struct zone *zone, struct scan_control *sc) >> > max_zone_concurrent_reclaimers) >> > break; >> > >> > - schedule(); >> > + io_schedule(); >> >> Hmm. We have many cond_resched which is not io_schedule in vmscan.c. > > cond_resched don't mean sleep on wait queue. it's similar to yield. I confused it. Thanks for correcting me. :) > >> In addition, if system doesn't have swap device space and out of page cache >> due to heavy memory pressue, VM might scan & drop pages until priority is zero >> or zone is unreclaimable. >> >> I think it would be not a IO wait. > > two point. > 1. For long time, Administrator usually watch iowait% at heavy memory pressure. I > don't hope change this without reasonable reason. 2. iowait makes scheduler > bonus a bit, vmscan task should have many time slice than memory consume > task. it improve VM stabilization. AFAIK, CFS scheduler doesn't give the bonus to I/O wait task any more. > > but I agree the benefit isn't so big. if we have reasonable reason, I > don't oppose use schedule(). > > > > -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |