From: Matthew Wilcox <willy@infradead.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
darrick.wong@oracle.com, Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm/filemap.c: minor optimization in write_iter file operation
Date: Sun, 18 Nov 2018 17:03:00 -0800 [thread overview]
Message-ID: <20181119010300.GD7861@bombadil.infradead.org> (raw)
In-Reply-To: <CALOAHbAfWkAYJPTRfyPmHKSmg7UEhtnamzUVx9xd4oYkqi_x8g@mail.gmail.com>
On Sun, Nov 18, 2018 at 11:02:19PM +0800, Yafang Shao wrote:
> On Sun, Nov 18, 2018 at 8:13 PM Matthew Wilcox <willy@infradead.org> wrote:
> > Did you check the before/after code generation with this patch applied?
>
> Yes, I did.
> My oompiler is gcc-4.8.5, a litte old, and with CONFIG_CC_OPTIMIZE_FOR_SIZE on.
> > with gcc 8.2.0, I see no difference, indicating that the compiler already
> > makes this optimisation.
>
> Could pls. try set CONFIG_CC_OPTIMIZE_FOR_SIZE on and then compare them again ?
Actually it was already on:
# CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE is not set
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
I happened to build it in my build-tiny output tree.
prev parent reply other threads:[~2018-11-19 1:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-18 12:02 [PATCH] mm/filemap.c: minor optimization in write_iter file operation Yafang Shao
2018-11-18 12:13 ` Matthew Wilcox
2018-11-18 15:02 ` Yafang Shao
2018-11-19 1:03 ` Matthew Wilcox [this message]
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