On Tue, May 31, 2011 at 01:14:15AM +0900, Minchan Kim wrote:
> On Mon, May 30, 2011 at 02:13:00PM +0100, Mel Gorman wrote:
> > Asynchronous compaction is used when promoting to huge pages. This is
> > all very nice but if there are a number of processes in compacting
> > memory, a large number of pages can be isolated. An "asynchronous"
> > process can stall for long periods of time as a result with a user
> > reporting that firefox can stall for 10s of seconds. This patch aborts
> > asynchronous compaction if too many pages are isolated as it's better to
> > fail a hugepage promotion than stall a process.
> >
> > If accepted, this should also be considered for 2.6.39-stable. It should
> > also be considered for 2.6.38-stable but ideally [11bc82d6: mm:
> > compaction: Use async migration for __GFP_NO_KSWAPD and enforce no
> > writeback] would be applied to 2.6.38 before consideration.
> >
> > Reported-and-Tested-by: Ury Stankevich <urykhy@xxxxxxxxx>
> > Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
> Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
>
Thanks
> I have a nitpick below.
> Otherwise, looks good to me.
>
> > ---
> > mm/compaction.c | 32 ++++++++++++++++++++++++++------
> > 1 files changed, 26 insertions(+), 6 deletions(-)
> >
> > diff --git a/mm/compaction.c b/mm/compaction.c
> > index 021a296..331a2ee 100644
> > --- a/mm/compaction.c
> > +++ b/mm/compaction.c
> > @@ -240,11 +240,20 @@ static bool too_many_isolated(struct zone *zone)
> > return isolated > (inactive + active) / 2;
> > }
> >
> > +/* possible outcome of isolate_migratepages */
> > +typedef enum {
> > + ISOLATE_ABORT, /* Abort compaction now */
> > + ISOLATE_NONE, /* No pages isolated, continue scanning */
> > + ISOLATE_SUCCESS, /* Pages isolated, migrate */
> > +} isolate_migrate_t;
> > +
> > /*
> > * Isolate all pages that can be migrated from the block pointed to by
> > * the migrate scanner within compact_control.
> > + *
> > + * Returns false if compaction should abort at this point due to congestion.
>
> false? I think it would be better to use explicit word, ISOLATE_ABORT.
>
Oops, thanks for pointing that out. I'll post a V2 once it has been
figured out why NR_ISOLATE_* is getting screwed up on !CONFIG_SMP.
--
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>