From: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@linux.com>
Cc: Waiman Long <Waiman.Long@hpe.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jan Kara <jack@suse.com>, Jeff Layton <jlayton@poochiereds.net>,
"J. Bruce Fields" <bfields@fieldses.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andi Kleen <andi@firstfloor.org>,
Dave Chinner <dchinner@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [PATCH v4 0/5] vfs: Use dlock list for SB's s_inodes list
Date: Mon, 25 Jul 2016 13:41:32 -0400 [thread overview]
Message-ID: <20160725174132.GC19588@mtj.duckdns.org> (raw)
In-Reply-To: <alpine.DEB.2.20.1607250846560.23039@east.gentwo.org>
Hello, Christoph.
On Mon, Jul 25, 2016 at 08:48:25AM -0500, Christoph Lameter wrote:
> On Fri, 22 Jul 2016, Waiman Long wrote:
>
> > - Add a new patch to make the percpu head structure cacheline aligned
> > to prevent cacheline contention from disrupting the performance
> > of nearby percpu variables.
>
> It would be better not to use the percpu allocation etc for this.
> Given the frequency of off node data access I would say that the data
> structure does not qualify as per cpu data. You have per cpu data items
> yes but this is not used as per cpu data.
I don't get it. What's the harm of using percpu memory here? Other
percpu data structures have remote access too. They're to a lower
degree but I don't see a clear demarcation line and making addtions
per-cpu seems to have significant benefits here. If there's a better
way of splitting the list and locking, sure, let's try that but short
of that I don't see anything wrong with doing this per-cpu.
Thanks.
--
tejun
next prev parent reply other threads:[~2016-07-25 17:41 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-22 20:35 [PATCH v4 0/5] vfs: Use dlock list for SB's s_inodes list Waiman Long
2016-07-22 20:35 ` [PATCH v4 1/5] lib/dlock-list: Distributed and lock-protected lists Waiman Long
2016-07-22 20:35 ` [PATCH v4 2/5] fsnotify: Simplify inode iteration on umount Waiman Long
2016-07-22 20:35 ` [PATCH v4 3/5] vfs: Remove unnecessary list_for_each_entry_safe() variants Waiman Long
2016-07-22 20:35 ` [PATCH v4 4/5] vfs: Use dlock list for superblock's inode list Waiman Long
2016-07-22 20:35 ` [PATCH v4 5/5] lib/dlock-list: Allow cacheline alignment of percpu head Waiman Long
2016-07-25 13:48 ` [PATCH v4 0/5] vfs: Use dlock list for SB's s_inodes list Christoph Lameter
2016-07-25 17:41 ` Tejun Heo [this message]
2016-07-27 15:12 ` Christoph Lameter
2016-08-09 3:26 ` Waiman Long
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