On Wed, May 18, 2011 at 02:44:48PM +0900, Minchan Kim wrote:
> On Wed, May 18, 2011 at 10:05 AM, KOSAKI Motohiro
> <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
> >> It would be better to put cond_resched after balance_pgdat?
> >>
> >> diff --git a/mm/vmscan.c b/mm/vmscan.c
> >> index 292582c..61c45d0 100644
> >> --- a/mm/vmscan.c
> >> +++ b/mm/vmscan.c
> >> @@ -2753,6 +2753,7 @@ static int kswapd(void *p)
> >> if (!ret) {
> >> trace_mm_vmscan_kswapd_wake(pgdat->node_id,
> >> order);
> >> order = balance_pgdat(pgdat,
> >> order,&classzone_idx);
> >> + cond_resched();
> >> }
> >> }
> >> return 0;
> >>
> >>>>> While it appears unlikely, there are bad conditions which can result
> >>>
> >>> in cond_resched() being avoided.
> >
> > Every reclaim priority decreasing or every shrink_zone() calling makes more
> > fine grained preemption. I think.
>
> It could be.
> But in direct reclaim case, I have a concern about losing pages
> reclaimed to other tasks by preemption.
>
> Hmm,, anyway, we also needs test.
> Hmm,, how long should we bother them(Colins and James)?
> First of all, Let's fix one just between us and ask test to them and
> send the last patch to akpm.
>
> 1. shrink_slab
> 2. right after balance_pgdat
> 3. shrink_zone
> 4. reclaim priority decreasing routine.
>
> Now, I vote 1) and 2).
>
I've already submitted a pair of patches for option 1. I don't think
option 2 gains us anything. I think it's more likely we should worry
about all_unreclaimable being set when shrink_slab is returning 0 and we
are encountering so many dirty pages that pages_scanned is high enough.
--
Mel Gorman
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>