| Message ID | 1584500541-46817-2-git-send-email-yang.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4,1/2] mm: swap: make page_evictable() inline | expand |
On Wed, Mar 18, 2020 at 11:02:21AM +0800, Yang Shi wrote: > Memory barrier is needed after setting LRU bit, but smp_mb() is too > strong. Some architectures, i.e. x86, imply memory barrier with atomic > operations, so replacing it with smp_mb__after_atomic() sounds better, > which is nop on strong ordered machines, and full memory barriers on > others. With this change the vm-scalability cases would perform better > on x86, I saw total 6% improvement with this patch and previous inline > fix. > > The test data (lru-file-readtwice throughput) against v5.6-rc4: > mainline w/ inline fix w/ both (adding this) > 150MB 154MB 159MB > > Fixes: 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs") > Acked-by: Vlastimil Babka <vbabka@suse.cz> > Reviewed-and-Tested-by: Shakeel Butt <shakeelb@google.com> > Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
diff --git a/mm/swap.c b/mm/swap.c index cf39d24..74ea08a 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -931,7 +931,6 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, VM_BUG_ON_PAGE(PageLRU(page), page); - SetPageLRU(page); /* * Page becomes evictable in two ways: * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()]. @@ -958,7 +957,8 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, * looking at the same page) and the evictable page will be stranded * in an unevictable LRU. */ - smp_mb(); + SetPageLRU(page); + smp_mb__after_atomic(); if (page_evictable(page)) { lru = page_lru(page);
Memory barrier is needed after setting LRU bit, but smp_mb() is too strong. Some architectures, i.e. x86, imply memory barrier with atomic operations, so replacing it with smp_mb__after_atomic() sounds better, which is nop on strong ordered machines, and full memory barriers on others. With this change the vm-scalability cases would perform better on x86, I saw total 6% improvement with this patch and previous inline fix. The test data (lru-file-readtwice throughput) against v5.6-rc4: mainline w/ inline fix w/ both (adding this) 150MB 154MB 159MB Fixes: 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs") Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-and-Tested-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> --- v3: * Added Shakeel's review-and-test signature. v2: * Solved the comment from Vlastimil and added his Ack. mm/swap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)