From: Tejun Heo <tj@kernel.org>
To: Rik van Riel <riel@surriel.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Jan Kara <jack@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
kernel-team@fb.com
Subject: Re: [PATCH] bdi: Move cgroup bdi_writeback to a dedicated low concurrency workqueue
Date: Wed, 23 May 2018 16:17:36 -0700 [thread overview]
Message-ID: <20180523231736.GT1718769@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <1527112995.7898.31.camel@surriel.com>
Hello, Rik.
On Wed, May 23, 2018 at 06:03:15PM -0400, Rik van Riel wrote:
> Dumb question. Does setting max_active to 1 mean
> that every cgwb_release_workfn() ends up forcing
> another RCU grace period on the whole system, while
> today you might have a bunch of them waiting on the
> same RCU grace period advance?
>
> Would it be faster to have some number (up to 16?)
> push RCU once, at the same time, instead of having
> each of them push RCU into a next grace period one
> after another?
Oh yeah, you're absolutely right. This would end up doing a lot of
back-to-back synchronize_rcu_expedited() calls which can't be good.
I'll send a patch to push it upto 16.
Thanks.
--
tejun
next prev parent reply other threads:[~2018-05-23 23:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-23 17:56 [PATCH] bdi: Move cgroup bdi_writeback to a dedicated low concurrency workqueue Tejun Heo
2018-05-23 18:39 ` Paul E. McKenney
2018-05-23 18:51 ` Tejun Heo
2018-05-23 19:10 ` Paul E. McKenney
2018-05-23 21:29 ` Jens Axboe
2018-05-23 22:03 ` Rik van Riel
2018-05-23 23:17 ` Tejun Heo [this message]
2018-05-23 23:25 ` [PATCH] bdi: Increase the concurrecy level of cgwb_release_wq Tejun Heo
2018-05-24 10:19 ` [PATCH] bdi: Move cgroup bdi_writeback to a dedicated low concurrency workqueue Jan Kara
2018-05-24 14:00 ` Tejun Heo
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