From: Christoph Lameter <cl@linux.com>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
Andrew Morton <akpm@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Jesper Dangaard Brouer <brouer@redhat.com>,
rostedt@goodmis.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/2] mm/slub: optimize alloc/free fastpath by removing preemption on/off
Date: Thu, 8 Jan 2015 21:34:07 -0600 (CST) [thread overview]
Message-ID: <alpine.DEB.2.11.1501082133350.22140@gentwo.org> (raw)
In-Reply-To: <20150108074447.GA25453@js1304-P5Q-DELUXE>
On Thu, 8 Jan 2015, Joonsoo Kim wrote:
> > You'd need a smp_wmb() in between tid and c in the loop then, which
> > looks quite unpleasant. All in all disabling preemption isn't really
> > that expensive, and you should redo your performance number if you go
> > this way.
>
> This barrier() is not for read/write synchronization between cpus.
> All read/write operation to cpu_slab would happen on correct cpu in
> successful case. What I'd need to guarantee here is to prevent
> reordering between fetching operation for correctness of algorithm. In
> this case, barrier() seems enough to me. Am I wrong?
You are right.
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next prev parent reply other threads:[~2015-01-09 3:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-05 1:36 Joonsoo Kim
2015-01-05 1:36 ` [PATCH 2/2] mm: don't use compound_head() in virt_to_head_page() Joonsoo Kim
2015-01-05 14:53 ` Christoph Lameter
2015-01-05 14:52 ` [PATCH 1/2] mm/slub: optimize alloc/free fastpath by removing preemption on/off Christoph Lameter
2015-01-06 3:03 ` Davidlohr Bueso
2015-01-06 8:09 ` Joonsoo Kim
2015-01-06 17:02 ` Davidlohr Bueso
2015-01-08 7:44 ` Joonsoo Kim
2015-01-09 3:34 ` Christoph Lameter [this message]
2015-01-05 8:37 Hillf Danton
2015-01-06 1:32 ` Joonsoo Kim
2015-01-06 2:25 ` Steven Rostedt
2015-01-06 8:27 ` Joonsoo Kim
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