From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta8.messagelabs.com (mail6.bemta8.messagelabs.com [216.82.243.55]) by kanga.kvack.org (Postfix) with ESMTP id 573F46B0083 for ; Tue, 7 Jun 2011 11:07:13 -0400 (EDT) From: Mel Gorman Subject: [PATCH 4/4] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous Date: Tue, 7 Jun 2011 16:07:05 +0100 Message-Id: <1307459225-4481-5-git-send-email-mgorman@suse.de> In-Reply-To: <1307459225-4481-1-git-send-email-mgorman@suse.de> References: <1307459225-4481-1-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Andrea Arcangeli , Minchan Kim , Thomas Sattler , Ury Stankevich , Andi Kleen , linux-mm , linux-kernel 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. Reported-and-tested-by: Ury Stankevich Signed-off-by: Mel Gorman --- mm/compaction.c | 28 +++++++++++++++++++++++----- 1 files changed, 23 insertions(+), 5 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 5c744ab..cb28580 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -251,11 +251,18 @@ 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. */ -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; @@ -272,7 +279,7 @@ 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; } /* @@ -281,10 +288,14 @@ 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 */ @@ -369,7 +380,7 @@ static unsigned long isolate_migratepages(struct zone *zone, trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); - return cc->nr_migratepages; + return ISOLATE_SUCCESS; } /* @@ -533,8 +544,14 @@ 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, @@ -558,6 +575,7 @@ 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); -- 1.7.3.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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: email@kvack.org