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From: Miklos Szeredi <miklos@szeredi.hu>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/2] fuse: Move clear_bit() up in request_end()
Date: Tue, 7 Aug 2018 14:22:51 +0200	[thread overview]
Message-ID: <CAJfpeguKJ2mAJbZjg+RVrzsGGJz-6WJ5Oa821Pw+udcc8E5HnA@mail.gmail.com> (raw)
In-Reply-To: <153303273523.387.7541221195413649436.stgit@localhost.localdomain>

On Tue, Jul 31, 2018 at 12:25 PM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> Nobody can clear FR_BACKGROUND bit on processing
> request in parallel, so it's possible to do it
> out of fc->lock.

Moving such a cheap operation outside the splinlock won't make any
difference in real life.

And anyway the biggest problem with fc->lock is not contention (hold
for long period of time), I would guess, but cachline pingponging
(being acquired on different CPUs one after the other).

So there's definitely work to do regarding locking in fuse, but it
needs a bigger axe.

Thanks,
Miklos

  reply	other threads:[~2018-08-07 14:36 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-31 10:25 [PATCH 0/2] fuse: Small cleanup series Kirill Tkhai
2018-07-31 10:25 ` [PATCH 1/2] fuse: Use list_first_entry() in flush_bg_queue() Kirill Tkhai
2018-08-07 12:26   ` Miklos Szeredi
2018-07-31 10:25 ` [PATCH 2/2] fuse: Move clear_bit() up in request_end() Kirill Tkhai
2018-08-07 12:22   ` Miklos Szeredi [this message]
2018-08-07 12:32     ` Kirill Tkhai

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