From: Andrew Morton <akpm@linux-foundation.org>
To: Alex Shi <alex.shi@linux.alibaba.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/vmstat: don't do count if no needs
Date: Mon, 20 Jul 2020 16:14:04 -0700 [thread overview]
Message-ID: <20200720161404.bd0c24560114bf48d6acbaff@linux-foundation.org> (raw)
In-Reply-To: <1ef9baa0-9788-5917-2590-a8c3fc593b81@linux.alibaba.com>
On Mon, 20 Jul 2020 13:42:45 +0800 Alex Shi <alex.shi@linux.alibaba.com> wrote:
>
> For couple of vmstat account funcs, the caller usually doesn't check the
> delta value, if delta == 0, irq or atomic operator is a waste. That's
> better to be skipped, also add unlikey() since !delta is less happened.
>
> ...
>
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -321,6 +321,9 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
> long x;
> long t;
>
> + if (unlikely(!delta))
> + return;
> +
Do we know that delta==0 is frequent enough to make the change a net
benefit?
next prev parent reply other threads:[~2020-07-20 23:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 5:23 [PATCH] mm/vmstat: don't do count if no needs Alex Shi
2020-07-20 5:42 ` Alex Shi
2020-07-20 23:14 ` Andrew Morton [this message]
2020-07-21 3:07 ` Alex Shi
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