From: Greg KH <greg@kroah.com>
To: Muchun Song <songmuchun@bytedance.com>
Cc: Matthew Wilcox <willy@infradead.org>,
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: Thu, 21 May 2020 18:16:23 +0200 [thread overview]
Message-ID: <20200521161623.GA3502608@kroah.com> (raw)
In-Reply-To: <CAMZfGtVxPevhTy8LMpKUtkk1jX86doiPD0nOTRuKg25+8Vz=ag@mail.gmail.com>
On Fri, May 22, 2020 at 12:06:46AM +0800, Muchun Song wrote:
> 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.
Did you test this and prove that it is safe and "faster"? If so, you
always have to show that in your changelog. Please fix it up and
resend.
thanks,
greg k-h
next prev parent reply other threads:[~2020-05-21 16:17 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 12:38 [PATCH] files: Use rcu lock to get the file structures for better performance Muchun Song
2020-05-21 15:21 ` Matthew Wilcox
2020-05-21 16:06 ` [External] " Muchun Song
2020-05-21 16:16 ` Greg KH [this message]
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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