|From:||Mel Gorman <firstname.lastname@example.org>|
|To:||Mel Gorman <email@example.com>, KOSAKI Motohiro <firstname.lastname@example.org>, Rik van Riel <email@example.com>, Christoph Lameter <firstname.lastname@example.org>, email@example.com, Wu Fengguang <firstname.lastname@example.org>, email@example.com|
|Subject:||[PATCH 0/3] [RFC] Functional fix to zone_reclaim() and bring behaviour more in line with expectations|
|Date:||Mon, 8 Jun 2009 14:01:27 +0100|
|Cc:||linux-mm <firstname.lastname@example.org>, LKML <email@example.com>|
A bug was brought to my attention against a distro kernel but it affects mainline and I believe problems like this have been reported in various guises on the mailing lists although I don't have specific examples at the moment. The problem that was reported that led to this patchset was that malloc() stalled for a long time (minutes in some cases) if a large tmpfs mount was occupying a large percentage of memory overall. The pages did not get cleaned or reclaimed by zone_reclaim() because the zone_reclaim_mode was unsuitable, but the lists are uselessly scanned frequencly making the CPU spin at near 100%. I do not have the bug resolved yet although I believe patch 1 of this series addresses it and am waiting to hear back from the bug reporter. However, the fix should work two other patches in this series also should bring zone_reclaim() more in line with expectations. Patch 1 reintroduces zone_reclaim_interval to catch the situation where zone_reclaim() cannot tell in advance that the scan is a waste of time. Patch 2 alters the heuristics that zone_reclaim() uses to determine if the scan should go ahead. Currently, it is basically assuming zone_reclaim_mode is 1 Patch 3 notes that zone_reclaim() returning a failure automatically means the zone is marked full. This is not always true. It could have failed because the GFP mask or zone_reclaim_mode are unsuitable. The patch makes zone_reclaim() more careful about marking zones temporarily full Note, this patchset has not been tested heavily. Comments? Documentation/sysctl/vm.txt | 13 +++++++++++ include/linux/mmzone.h | 9 ++++++++ include/linux/swap.h | 1 + kernel/sysctl.c | 9 ++++++++ mm/internal.h | 4 +++ mm/page_alloc.c | 26 +++++++++++++++++++--- mm/vmscan.c | 48 +++++++++++++++++++++++++++++++++++++----- 7 files changed, 100 insertions(+), 10 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to firstname.lastname@example.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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