From: Yang Shi <yang.shi@linux.alibaba.com>
To: shakeelb@google.com, vbabka@suse.cz, willy@infradead.org,
akpm@linux-foundation.org
Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [v2 PATCH 2/2] mm: swap: use smp_mb__after_atomic() to order LRU bit set
Date: Tue, 17 Mar 2020 06:24:15 +0800 [thread overview]
Message-ID: <1584397455-28701-2-git-send-email-yang.shi@linux.alibaba.com> (raw)
In-Reply-To: <1584397455-28701-1-git-send-email-yang.shi@linux.alibaba.com>
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-calability 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")
Cc: Shakeel Butt <shakeelb@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
v2: * Solved the comment from Vlastimil and added his Ack.
mm/swap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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);
--
1.8.3.1
next prev parent reply other threads:[~2020-03-16 22:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-16 22:24 [v2 PATCH 1/2] mm: swap: make page_evictable() inline Yang Shi
2020-03-16 22:24 ` Yang Shi [this message]
2020-03-16 23:47 ` [v2 PATCH 2/2] mm: swap: use smp_mb__after_atomic() to order LRU bit set Shakeel Butt
2020-03-16 23:46 ` [v2 PATCH 1/2] mm: swap: make page_evictable() inline Shakeel Butt
2020-03-17 2:05 ` Yang Shi
2020-03-17 3:00 ` kbuild test robot
2020-03-17 3:24 ` Yang Shi
2020-03-17 3:15 ` kbuild test robot
2020-03-17 8:59 ` Vlastimil Babka
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