From: Pavel Begunkov <asml.silence@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fs: optimise generic_write_check_limits()
Date: Sat, 7 Aug 2021 11:05:38 +0100 [thread overview]
Message-ID: <a01568b8-a10c-c260-a0fe-3161a8075dba@gmail.com> (raw)
In-Reply-To: <YQ04/NFn8b6cykPQ@casper.infradead.org>
On 8/6/21 2:28 PM, Matthew Wilcox wrote:
> On Fri, Aug 06, 2021 at 12:22:10PM +0100, Pavel Begunkov wrote:
>> Even though ->s_maxbytes is used by generic_write_check_limits() only in
>> case of O_LARGEFILE, the value is loaded unconditionally, which is heavy
>> and takes 4 indirect loads. Optimise it by not touching ->s_maxbytes,
>> if it's not going to be used.
>
> Is this "optimisation" actually worth anything? Look at how
> force_o_largefile() is used. I would suggest that on the vast majority
> of machines, O_LARGEFILE is always set.
Makes sense to leave it alone then, thanks
--
Pavel Begunkov
next prev parent reply other threads:[~2021-08-07 10:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-06 11:22 [PATCH] fs: optimise generic_write_check_limits() Pavel Begunkov
2021-08-06 13:28 ` Matthew Wilcox
2021-08-07 10:05 ` Pavel Begunkov [this message]
2021-08-08 14:41 ` David Laight
2021-08-08 15:34 ` Matthew Wilcox
2021-08-06 13:46 ` Al Viro
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