Messages in this thread Patch in this message | | | From | Vlastimil Babka <> | Subject | [PATCH 2/2] mm/compaction: cleanup isolate_freepages() | Date | Tue, 15 Apr 2014 11:18:27 +0200 |
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isolate_freepages() is currently somewhat hard to follow thanks to many different pfn variables. Especially misleading is the name 'high_pfn' which looks like it is related to the 'low_pfn' variable, but in fact it is not.
This patch renames the 'high_pfn' variable to a hopefully less confusing name, and slightly changes its handling without a functional change. A comment made obsolete by recent changes is also updated.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz> 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 | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/mm/compaction.c b/mm/compaction.c index 627dc2e..169c7b2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -671,7 +671,7 @@ static void isolate_freepages(struct zone *zone, struct compact_control *cc) { struct page *page; - unsigned long high_pfn, low_pfn, pfn, z_end_pfn; + unsigned long pfn, low_pfn, next_free_pfn, z_end_pfn; int nr_freepages = cc->nr_freepages; struct list_head *freelist = &cc->freepages; @@ -688,11 +688,10 @@ static void isolate_freepages(struct zone *zone, low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages); /* - * Take care that if the migration scanner is at the end of the zone - * that the free scanner does not accidentally move to the next zone - * in the next isolation cycle. + * Seed the value for max(next_free_pfn, pfn) updates. If there are + * none, the pfn < low_pfn check will kick in. */ - high_pfn = min(low_pfn, pfn); + next_free_pfn = 0; z_end_pfn = zone_end_pfn(zone); @@ -754,7 +753,7 @@ static void isolate_freepages(struct zone *zone, */ if (isolated) { cc->finished_update_free = true; - high_pfn = max(high_pfn, pfn); + next_free_pfn = max(next_free_pfn, pfn); } } @@ -766,9 +765,9 @@ static void isolate_freepages(struct zone *zone, * so that compact_finished() may detect this */ if (pfn < low_pfn) - cc->free_pfn = max(pfn, zone->zone_start_pfn); - else - cc->free_pfn = high_pfn; + next_free_pfn = max(pfn, zone->zone_start_pfn); + + cc->free_pfn = next_free_pfn; cc->nr_freepages = nr_freepages; } -- 1.8.4.5
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