From: David Rientjes <rientjes@google.com>
To: Christoph Lameter <cl@linux.com>
Cc: Glauber Costa <glommer@parallels.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Michal Hocko <mhocko@suse.cz>,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH] slab: Ignore internal flags in cache creation
Date: Fri, 28 Sep 2012 13:36:16 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1209281332460.21335@chino.kir.corp.google.com> (raw)
In-Reply-To: <0000013a0d314c3f-e5b12d01-7a99-4368-82a0-f5de4d46f804-000000@email.amazonses.com>
On Fri, 28 Sep 2012, Christoph Lameter wrote:
> > > This means touching another field from critical paths of the allocators.
> > > It would increase the cache footprint and therefore reduce performance.
> > >
> >
> > To clarify your statement, you're referring to the mm/slab.c allocation of
> > new slab pages and when debugging is enabled as "critical paths", correct?
> > We would disagree on that point.
>
> This is not debugging specific. Flags are also consulted to do RCU
> processing and other things.
>
There is no "critical path" in mm/slab.c that tests CFLGS_OFF_SLAB; the
flag itself is used to determine where slab management is done and you
certainly wouldn't want to find this for any path that is critical.
If you'd like to disagree with that, please show the code and why you
consider increasing the cache footprint in that case to be critical to
performance.
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next prev parent reply other threads:[~2012-09-28 20:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-25 11:17 Glauber Costa
2012-09-25 16:26 ` Christoph Lameter
2012-09-26 0:46 ` David Rientjes
2012-09-26 8:43 ` Glauber Costa
2012-09-27 1:16 ` David Rientjes
2012-09-27 6:59 ` Glauber Costa
2012-09-27 22:56 ` David Rientjes
2012-09-28 7:46 ` Glauber Costa
2012-09-28 20:25 ` David Rientjes
2012-09-28 14:12 ` Christoph Lameter
2012-09-28 20:39 ` David Rientjes
2012-09-28 21:20 ` Christoph Lameter
2012-09-28 23:11 ` David Rientjes
2012-10-01 17:54 ` Christoph Lameter
2012-10-01 7:28 ` Pekka Enberg
2012-10-01 7:58 ` Glauber Costa
2012-09-27 13:54 ` Christoph Lameter
2012-09-27 22:50 ` David Rientjes
2012-09-28 14:04 ` Christoph Lameter
2012-09-28 20:36 ` David Rientjes [this message]
2012-09-26 14:57 ` Christoph Lameter
2012-09-27 1:12 ` David Rientjes
2012-09-27 13:57 ` Christoph Lameter
2012-09-27 22:52 ` David Rientjes
2012-09-28 14:10 ` Christoph Lameter
2012-09-28 20:30 ` David Rientjes
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