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From: Muchun Song <songmuchun@bytedance.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: adobriyan@gmail.com, ast@kernel.org, daniel@iogearbox.net,
	kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com,
	john.fastabend@gmail.com, kpsingh@chromium.org,
	ebiederm@xmission.com, bernd.edlinger@hotmail.de,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [External] Re: [PATCH] files: Use rcu lock to get the file structures for better performance
Date: Fri, 22 May 2020 00:06:46 +0800
Message-ID: <CAMZfGtVxPevhTy8LMpKUtkk1jX86doiPD0nOTRuKg25+8Vz=ag@mail.gmail.com> (raw)
In-Reply-To: <20200521152117.GC28818@bombadil.infradead.org>

On Thu, May 21, 2020 at 11:21 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, May 21, 2020 at 08:38:35PM +0800, Muchun Song wrote:
> > There is another safe way to get the file structure without
> > holding the files->file_lock. That is rcu lock, and this way
> > has better performance. So use the rcu lock instead of the
> > files->file_lock.
>
> What makes you think this is safe?  Are you actually seeing contention
> on this spinlock?
>

I have read the doc which is in the Documentation/filesystems/files.txt.
If my understanding is correct, I think it is safe to use rcu lock.

Thanks.

-- 
Yours,
Muchun

  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-21 12:38 Muchun Song
2020-05-21 15:21 ` Matthew Wilcox
2020-05-21 16:06   ` Muchun Song [this message]
2020-05-21 16:16     ` [External] " Greg KH
2020-05-21 16:47 ` Matthew Wilcox
2020-05-22  7:52   ` [External] " Muchun Song
2020-05-22 11:43     ` Matthew Wilcox

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