From: Johannes Weiner <hannes@cmpxchg.org>
To: Yang Shi <yang.shi@linux.alibaba.com>
Cc: shakeelb@google.com, vbabka@suse.cz, willy@infradead.org,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [v4 PATCH 2/2] mm: swap: use smp_mb__after_atomic() to order LRU bit set
Date: Thu, 19 Mar 2020 10:03:05 -0400 [thread overview]
Message-ID: <20200319140305.GC187654@cmpxchg.org> (raw)
In-Reply-To: <1584500541-46817-2-git-send-email-yang.shi@linux.alibaba.com>
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>
next prev parent reply other threads:[~2020-03-19 14:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 3:02 [v4 PATCH 1/2] mm: swap: make page_evictable() inline Yang Shi
2020-03-18 3:02 ` [v4 PATCH 2/2] mm: swap: use smp_mb__after_atomic() to order LRU bit set Yang Shi
2020-03-19 14:03 ` Johannes Weiner [this message]
2020-03-18 3:04 ` [v4 PATCH 1/2] mm: swap: make page_evictable() inline Matthew Wilcox
2020-03-19 14:01 ` Johannes Weiner
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