The patch titled
Subject: mm: Fix madvise WILLNEED performance problem
has been added to the -mm tree. Its filename is
mm-fix-madvise-willneed-performance-problem.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-fix-madvise-willneed-performance-problem.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-madvise-willneed-performance-problem.patch
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: Fix madvise WILLNEED performance problem
The calculation of the end page index was incorrect, leading to a
regression of 70% when running stress-ng. With this fix, we instead
see a performance improvement of 3%.
Link: https://lkml.kernel.org/r/20201109134851.29692-1-willy@xxxxxxxxxxxxx
Fixes: e6e88712e43b ("mm: optimise madvise WILLNEED")
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx>
Tested-by: Xing Zhengjun <zhengjun.xing@xxxxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Feng Tang <feng.tang@xxxxxxxxx>
Cc: "Chen, Rong A" <rong.a.chen@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/madvise.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/madvise.c~mm-fix-madvise-willneed-performance-problem
+++ a/mm/madvise.c
@@ -226,7 +226,7 @@ static void force_shm_swapin_readahead(s
struct address_space *mapping)
{
XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
- pgoff_t end_index = end / PAGE_SIZE;
+ pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
struct page *page;
rcu_read_lock();
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-fix-readahead_page_batch-for-retry-entries.patch
mm-fix-madvise-willneed-performance-problem.patch
