The patch titled
Subject: mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4
has been added to the -mm tree. Its filename is
mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4.patch
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------------------------------------------------------
From: Aaron Lu <aaron.lu@xxxxxxxxx>
Subject: mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4
Link: http://lkml.kernel.org/r/20180301062845.26038-4-aaron.lu@xxxxxxxxx
Link: http://lkml.kernel.org/r/20180309082431.GB30868@xxxxxxxxx
Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
Cc: Ying Huang <ying.huang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff -puN mm/page_alloc.c~mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4 mm/page_alloc.c
--- a/mm/page_alloc.c~mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4
+++ a/mm/page_alloc.c
@@ -1116,15 +1116,19 @@ static void free_pcppages_bulk(struct zo
if (bulkfree_pcp_prepare(page))
continue;
- list_add_tail(&page->lru, &head);
+ list_add(&page->lru, &head);
/*
* We are going to put the page back to the global
* pool, prefetch its buddy to speed up later access
* under zone->lock. It is believed the overhead of
- * calculating buddy_pfn here can be offset by reduced
- * memory latency later.
+ * an additional test and calculating buddy_pfn here
+ * can be offset by reduced memory latency later. To
+ * avoid excessive prefetching due to large count, only
+ * prefetch buddy for the last pcp->batch nr of pages.
*/
+ if (count > pcp->batch)
+ continue;
pfn = page_to_pfn(page);
buddy_pfn = __find_buddy_pfn(pfn, 0);
buddy = page + (buddy_pfn - pfn);
_
Patches currently in -mm which might be from aaron.lu@xxxxxxxxx are
mm-free_pcppages_bulk-update-pcp-count-inside.patch
mm-free_pcppages_bulk-do-not-hold-lock-when-picking-pages-to-free.patch
mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lock.patch
mm-free_pcppages_bulk-prefetch-buddy-while-not-holding-lockpatch-v4.patch
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