Messages in this thread | | | Date | Wed, 16 Apr 2014 10:52:59 +0900 | From | Joonsoo Kim <> | Subject | Re: [PATCH 1/2] mm/compaction: make isolate_freepages start at pageblock boundary |
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On Tue, Apr 15, 2014 at 11:18:26AM +0200, Vlastimil Babka wrote: > The compaction freepage scanner implementation in isolate_freepages() starts > by taking the current cc->free_pfn value as the first pfn. In a for loop, it > scans from this first pfn to the end of the pageblock, and then subtracts > pageblock_nr_pages from the first pfn to obtain the first pfn for the next > for loop iteration. > > This means that when cc->free_pfn starts at offset X rather than being aligned > on pageblock boundary, the scanner will start at offset X in all scanned > pageblock, ignoring potentially many free pages. Currently this can happen when > a) zone's end pfn is not pageblock aligned, or > b) through zone->compact_cached_free_pfn with CONFIG_HOLES_IN_ZONE enabled and > a hole spanning the beginning of a pageblock > > This patch fixes the problem by aligning the initial pfn in isolate_freepages() > to pageblock boundary. This also allows to replace the end-of-pageblock > alignment within the for loop with a simple pageblock_nr_pages increment. > > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > Reported-by: Heesub Shin <heesub.shin@samsung.com> > Cc: Minchan Kim <minchan@kernel.org> > Cc: Mel Gorman <mgorman@suse.de> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> > Cc: Michal Nazarewicz <mina86@mina86.com> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Christoph Lameter <cl@linux.com> > Cc: Rik van Riel <riel@redhat.com> > --- > mm/compaction.c | 22 ++++++++++++---------- > 1 file changed, 12 insertions(+), 10 deletions(-)
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
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