Subject: + mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch added to -mm tree
To: iamjoonsoo.kim@xxxxxxx,mgorman@xxxxxxx,riel@xxxxxxxxxx,vbabka@xxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 21 Feb 2014 14:52:54 -0800
The patch titled
Subject: mm/compaction: change the timing to check to drop the spinlock
has been added to the -mm tree. Its filename is
mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
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From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: mm/compaction: change the timing to check to drop the spinlock
It is odd to drop the spinlock when we scan (SWAP_CLUSTER_MAX - 1) th pfn
page. This may results in below situation while isolating migratepage.
1. try isolate 0x0 ~ 0x200 pfn pages.
2. When low_pfn is 0x1ff, ((low_pfn+1) % SWAP_CLUSTER_MAX) == 0, so drop
the spinlock.
3. Then, to complete isolating, retry to aquire the lock.
I think that it is better to use SWAP_CLUSTER_MAX th pfn for checking the
criteria about dropping the lock. This has no harm 0x0 pfn, because, at
this time, locked variable would be false.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/compaction.c~mm-compaction-change-the-timing-to-check-to-drop-the-spinlock mm/compaction.c
--- a/mm/compaction.c~mm-compaction-change-the-timing-to-check-to-drop-the-spinlock
+++ a/mm/compaction.c
@@ -481,7 +481,7 @@ isolate_migratepages_range(struct zone *
cond_resched();
for (; low_pfn < end_pfn; low_pfn++) {
/* give a chance to irqs before checking need_resched() */
- if (locked && !((low_pfn+1) % SWAP_CLUSTER_MAX)) {
+ if (locked && !(low_pfn % SWAP_CLUSTER_MAX)) {
if (should_release_lock(&zone->lru_lock)) {
spin_unlock_irqrestore(&zone->lru_lock, flags);
locked = false;
_
Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are
kthread-ensure-locality-of-task_struct-allocations.patch
mm-hugetlb-unify-region-structure-handling.patch
mm-hugetlb-improve-cleanup-resv_map-parameters.patch
mm-hugetlb-fix-race-in-region-tracking.patch
mm-hugetlb-remove-resv_map_put.patch
mm-hugetlb-use-vma_resv_map-map-types.patch
mm-hugetlb-improve-page-fault-scalability.patch
mm-hugetlb-improve-page-fault-scalability-fix.patch
mm-hugetlb-mark-some-bootstrap-functions-as-__init.patch
mm-compaction-avoid-isolating-pinned-pages.patch
mm-compaction-disallow-high-order-page-for-migration-target.patch
mm-compaction-do-not-call-suitable_migration_target-on-every-page.patch
mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
mm-compaction-check-pageblock-suitability-once-per-pageblock.patch
mm-compaction-clean-up-code-on-success-of-ballon-isolation.patch
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