Subject: [merged] mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch removed from -mm tree
To: iamjoonsoo.kim@xxxxxxx,mgorman@xxxxxxx,riel@xxxxxxxxxx,vbabka@xxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 08 Apr 2014 13:36:27 -0700
The patch titled
Subject: mm/compaction: change the timing to check to drop the spinlock
has been removed from the -mm tree. Its filename was
mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
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
@@ -487,7 +487,7 @@ 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
origin.patch
mm-compactionc-isolate_freepages_block-small-tuneup.patch
linux-next.patch
page-owners-correct-page-order-when-to-free-page.patch
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