From: Mel Gorman <mgorman@techsingularity.net>
To: Yanfei Xu <yanfei.xu@windriver.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm/page_alloc: avoid counting event if no successful allocation
Date: Fri, 9 Jul 2021 13:26:01 +0100 [thread overview]
Message-ID: <20210709122601.GA3840@techsingularity.net> (raw)
In-Reply-To: <20210709102855.55058-2-yanfei.xu@windriver.com>
On Fri, Jul 09, 2021 at 06:28:55PM +0800, Yanfei Xu wrote:
> While the nr_populated is non-zero, however the nr_account might be
> zero if allocating fails. In this case, not to count event can save
> some cycles.
>
The much more likely path is that nr_account is positive so we avoid a
branch in the common case.
> And this commit extract the check of "page_array" from a while
> statement to avoid unnecessary checks for it.
>
I'm surprised the compiler does not catch that page_array is invariant
for the loop. Did you check if gcc generates different code is page_array
is explicitly checked once instead of putting it in the loop?
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2021-07-09 12:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 10:28 [PATCH 1/2] mm/page_alloc: correct return value when failing at preparing Yanfei Xu
2021-07-09 10:28 ` [PATCH 2/2] mm/page_alloc: avoid counting event if no successful allocation Yanfei Xu
2021-07-09 12:26 ` Mel Gorman [this message]
2021-07-10 11:31 ` Xu, Yanfei
2021-07-09 12:22 ` [PATCH 1/2] mm/page_alloc: correct return value when failing at preparing Mel Gorman
2021-07-10 6:58 ` Xu, Yanfei
2021-07-13 12:14 ` Mel Gorman
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