From: Christoph Lameter <cl@linux.com>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
Dave Hansen <dave.hansen@intel.com>,
Andi Kleen <ak@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH 1/2] Make the batch size of the percpu_counter configurable
Date: Tue, 30 Apr 2013 18:27:25 +0000 [thread overview]
Message-ID: <0000013e5c32f7fd-b4bf1b22-7924-42b5-b835-eb2b5926bbf6-000000@email.amazonses.com> (raw)
In-Reply-To: <1367344522.27102.184.camel@schen9-DESK>
On Tue, 30 Apr 2013, Tim Chen wrote:
> > But you will have to dereference the pointer whenever you want the batch
> > size from the hot path. Looks like it would be better to put the value
> > there directly. You have a list of percpu counters that can be traversed
> > to change the batch size.
> >
>
> I have considered that. But the list is not available unless we have
> CONFIG_HOTPLUG_CPU compiled in.
percpu counters are performance sensitive and with the pointer you
will need to reference another one increasing the cache footprint. You are
touching an additional cacheline somewhere in memory frequently. Not good.
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next prev parent reply other threads:[~2013-04-30 18:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-29 17:12 Tim Chen
2013-04-29 17:12 ` [PATCH 2/2] Make batch size for memory accounting configured according to size of memory Tim Chen
2013-05-01 5:09 ` Ric Mason
2013-05-01 16:07 ` Tim Chen
2013-04-30 13:32 ` [PATCH 1/2] Make the batch size of the percpu_counter configurable Christoph Lameter
2013-04-30 16:23 ` Tim Chen
2013-04-30 17:28 ` Christoph Lameter
2013-04-30 17:48 ` Tim Chen
2013-04-30 17:53 ` Christoph Lameter
2013-04-30 17:55 ` Tim Chen
2013-04-30 18:27 ` Christoph Lameter [this message]
2013-04-30 19:00 ` Tim Chen
2013-04-30 19:04 ` Tejun Heo
2013-04-30 20:50 ` Christoph Lameter
2013-04-30 17:34 ` Andi Kleen
2013-04-30 18:10 ` Eric Dumazet
2013-04-30 18:28 ` Tim Chen
2013-05-01 4:52 ` Simon Jeons
2013-05-01 15:53 ` Tim Chen
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