From: Eric Dumazet <eric.dumazet@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Alexander Duyck <alexander.duyck@gmail.com>,
linux-mm@kvack.org, netdev@vger.kernel.org
Subject: Re: [RFC PATCH] slub: RFC: Improving SLUB performance with 38% on NO-PREEMPT
Date: Thu, 04 Jun 2015 19:37:57 -0700 [thread overview]
Message-ID: <1433471877.1895.51.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <20150604103159.4744.75870.stgit@ivy>
On Thu, 2015-06-04 at 12:31 +0200, Jesper Dangaard Brouer wrote:
> This patch improves performance of SLUB allocator fastpath with 38% by
> avoiding the call to this_cpu_cmpxchg_double() for NO-PREEMPT kernels.
>
> Reviewers please point out why this change is wrong, as such a large
> improvement should not be possible ;-)
I am not sure if anyone already answered, but the cmpxchg_double()
is needed to avoid the ABA problem.
This is the whole point using tid _and_ freelist
Preemption is not the only thing that could happen here, think of
interrupts.
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next prev parent reply other threads:[~2015-06-05 2:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-04 10:31 Jesper Dangaard Brouer
2015-06-05 2:37 ` Eric Dumazet [this message]
2015-06-08 9:23 ` Jesper Dangaard Brouer
2015-06-08 9:39 ` Christoph Lameter
2015-06-08 9:58 ` Jesper Dangaard Brouer
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