From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <waiman.long@hpe.com>
Cc: Dave Chinner <david@fromorbit.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jan Kara <jack@suse.com>, Jeff Layton <jlayton@poochiereds.net>,
"J. Bruce Fields" <bfields@fieldses.org>,
Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux-foundation.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>, Andi Kleen <andi@firstfloor.org>,
Dave Chinner <dchinner@redhat.com>,
Scott J Norton <scott.norton@hp.com>,
Douglas Hatch <doug.hatch@hp.com>
Subject: Re: [RFC PATCH 1/2] lib/percpu-list: Per-cpu list with associated per-cpu locks
Date: Wed, 17 Feb 2016 17:22:16 +0100 [thread overview]
Message-ID: <20160217162216.GI6357@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <56C49CCA.7090805@hpe.com>
On Wed, Feb 17, 2016 at 11:16:10AM -0500, Waiman Long wrote:
> >So why not use RCU for the list iteration and avoid potentially large
> >lock hold times?
> >
>
> I know we can use RCU for singly linked list, but I don't think we can use
> that for doubly linked list as there is no easy way to make atomic changes
> to both prev and next pointers simultaneously unless you are taking about
> 16b cmpxchg which is only supported in some architecture.
See include/linux/rculist.h, the only constraint is that reverse
iteration is not allowed, because of what you say.
next prev parent reply other threads:[~2016-02-17 16:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 1:31 [RFC PATCH 0/2] vfs: Use per-cpu list for SB's s_inodes list Waiman Long
2016-02-17 1:31 ` [RFC PATCH 1/2] lib/percpu-list: Per-cpu list with associated per-cpu locks Waiman Long
2016-02-17 9:53 ` Dave Chinner
2016-02-17 11:00 ` Peter Zijlstra
2016-02-17 11:05 ` Peter Zijlstra
2016-02-17 16:16 ` Waiman Long
2016-02-17 16:22 ` Peter Zijlstra [this message]
2016-02-17 16:27 ` Christoph Lameter
2016-02-17 17:12 ` Waiman Long
2016-02-17 17:18 ` Peter Zijlstra
2016-02-17 17:41 ` Waiman Long
2016-02-17 18:22 ` Peter Zijlstra
2016-02-17 18:45 ` Waiman Long
2016-02-17 19:39 ` Peter Zijlstra
2016-02-17 11:10 ` Dave Chinner
2016-02-17 11:26 ` Peter Zijlstra
2016-02-17 11:36 ` Peter Zijlstra
2016-02-17 15:56 ` Waiman Long
2016-02-17 16:02 ` Peter Zijlstra
2016-02-17 15:13 ` Christoph Lameter
2016-02-17 1:31 ` [RRC PATCH 2/2] vfs: Use per-cpu list for superblock's inode list Waiman Long
2016-02-17 7:16 ` Ingo Molnar
2016-02-17 15:40 ` Waiman Long
2016-02-17 10:37 ` Dave Chinner
2016-02-17 16:08 ` Waiman Long
2016-02-18 23:58 ` [RFC PATCH 0/2] vfs: Use per-cpu list for SB's s_inodes list Dave Chinner
2016-02-19 21:04 ` Long, Wai Man
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