On Mon, 30 May 2011 14:13:00 +0100 Mel Gorman <[email protected]> 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 <[email protected]> > Signed-off-by: Mel Gorman <[email protected]> Reviewed-by: KAMEZAWA Hiroyuki <[email protected]> BTW, I'm surprised to see both of vmscan.c and compaction.c has too_many_isolated().. in different logic ;) BTW, compaction ignores UNEVICTABLE LRU ? Thanks, -Kame > --- > 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. > */ > -static unsigned long isolate_migratepages(struct zone *zone, > +static isolate_migrate_t isolate_migratepages(struct zone *zone, > struct compact_control *cc) > { > unsigned long low_pfn, end_pfn; > @@ -261,7 +270,7 @@ static unsigned long isolate_migratepages(struct zone > *zone, > /* Do not cross the free scanner or scan within a memory hole */ > if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) { > cc->migrate_pfn = end_pfn; > - return 0; > + return ISOLATE_NONE; > } > > /* > @@ -270,10 +279,14 @@ static unsigned long isolate_migratepages(struct zone > *zone, > * delay for some time until fewer pages are isolated > */ > while (unlikely(too_many_isolated(zone))) { > + /* async migration should just abort */ > + if (!cc->sync) > + return ISOLATE_ABORT; > + > congestion_wait(BLK_RW_ASYNC, HZ/10); > > if (fatal_signal_pending(current)) > - return 0; > + return ISOLATE_ABORT; > } > > /* Time to isolate some pages for migration */ > @@ -358,7 +371,7 @@ static unsigned long isolate_migratepages(struct zone > *zone, > > trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); > > - return cc->nr_migratepages; > + return ISOLATE_SUCCESS; > } > > /* > @@ -522,9 +535,15 @@ static int compact_zone(struct zone *zone, struct > compact_control *cc) > unsigned long nr_migrate, nr_remaining; > int err; > > - if (!isolate_migratepages(zone, cc)) > + switch (isolate_migratepages(zone, cc)) { > + case ISOLATE_ABORT: > + goto out; > + case ISOLATE_NONE: > continue; > - > + case ISOLATE_SUCCESS: > + ; > + } > + > nr_migrate = cc->nr_migratepages; > err = migrate_pages(&cc->migratepages, compaction_alloc, > (unsigned long)cc, false, > @@ -547,6 +566,7 @@ static int compact_zone(struct zone *zone, struct > compact_control *cc) > > } > > +out: > /* Release free pages and check accounting */ > cc->nr_freepages -= release_freepages(&cc->freepages); > VM_BUG_ON(cc->nr_freepages != 0); > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. 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:"[email protected]";> [email protected] </a> _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
