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From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Hugh Dickins <hughd@google.com>,
	akpm@linux-foundation.org, alex.shi@linux.alibaba.com,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	liwang@redhat.com
Subject: Re: [PATCH 2/2] mm, page_alloc: use unlikely() in task_capc()
Date: Mon, 22 Jun 2020 09:58:08 +0100	[thread overview]
Message-ID: <20200622085808.GP3183@techsingularity.net> (raw)
In-Reply-To: <4a24f7af-3aa5-6e80-4ae6-8f253b562039@suse.cz>

On Wed, Jun 17, 2020 at 11:55:07AM +0200, Vlastimil Babka wrote:
> <SNIP>
>
> It makes no difference, at least on my gcc10 which seems to be smart enough to
> do the right thing. But yeah, your suggestion is more readable and precise and
> maybe can work better with a less smart compiler. Thanks.
> 
> ----8<----
> From 615eea6f6abe288ffb708aa0d1bdfbeaf30a4cbd Mon Sep 17 00:00:00 2001
> From: Vlastimil Babka <vbabka@suse.cz>
> Date: Tue, 16 Jun 2020 10:14:47 +0200
> Subject: [PATCH] mm, page_alloc: use unlikely() in task_capc()
> 
> Hugh noted that task_capc() could use unlikely(), as most of the time there is
> no capture in progress and we are in page freeing hot path. Indeed adding
> unlikely() produces assembly that better matches the assumption and moves
> all the tests away from the hot path.
> 
> I have also noticed that we don't need to test for cc->direct_compaction as the
> only place we set current->task_capture is compact_zone_order() which also
> always sets cc->direct_compaction true.
> 
> Suggested-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> Acked-by: Hugh Dickins <hughd@googlecom>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs

  reply	other threads:[~2020-06-22  8:58 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-10 20:48 [PATCH] mm, page_alloc: capture page in task context only Hugh Dickins
2020-06-11 15:43 ` Mel Gorman
2020-06-12 10:30 ` Vlastimil Babka
2020-06-15 21:03   ` Hugh Dickins
2020-06-16  7:45     ` Vlastimil Babka
2020-06-16  8:26       ` [PATCH 1/2] mm, compaction: make capture control handling safe wrt interrupts Vlastimil Babka
2020-06-16  8:26         ` [PATCH 2/2] mm, page_alloc: use unlikely() in task_capc() Vlastimil Babka
2020-06-16 20:29           ` Hugh Dickins
2020-06-17  9:55             ` Vlastimil Babka
2020-06-22  8:58               ` Mel Gorman [this message]
2020-06-16 20:18         ` [PATCH 1/2] mm, compaction: make capture control handling safe wrt interrupts Hugh Dickins

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