From: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@linux.com>
Cc: Shaohua Li <shaohua.li@intel.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH] percpu: preemptless __per_cpu_counter_add
Date: Thu, 28 Apr 2011 16:44:46 +0200 [thread overview]
Message-ID: <20110428144446.GC16552@htj.dyndns.org> (raw)
In-Reply-To: <alpine.DEB.2.00.1104280935460.16323@router.home>
On Thu, Apr 28, 2011 at 09:42:49AM -0500, Christoph Lameter wrote:
> > > Can you show in some tests how the chance of deviations is increased? If
> > > at all then in some special sitations. Maybe others get better?
> >
> > It's kinda obvious, isn't it? Do relatively low freq (say, every
> > 10ms) +1's and continuously do _sum(). Before, _sum() would never
> > deviate much from the real count. After, there will be @batch jumps.
> > If you still need proof code, I would write it but please note that
> > I'm pretty backed up.
>
> "Obvious" could mean that you are drawing conclusions without a proper
> reasoning chain. Here you assume certain things about the users of the
> counters. The same assumptions were made when we had the vm counter
> issues. The behavior of counter increments is typically not a regular
> stream but occurs in spurts.
Eh? Are you saying the above can't happen or the above doesn't
matter?
--
tejun
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next prev parent reply other threads:[~2011-04-28 14:46 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-13 14:45 percpu: preemptless __per_cpu_counter_add Christoph Lameter
2011-04-13 16:49 ` Christoph Lameter
2011-04-13 18:56 ` Tejun Heo
2011-04-13 20:22 ` [PATCH] " Christoph Lameter
2011-04-13 21:50 ` Tejun Heo
2011-04-13 22:17 ` Christoph Lameter
2011-04-13 22:23 ` Christoph Lameter
2011-04-13 23:55 ` Tejun Heo
2011-04-14 2:00 ` Eric Dumazet
2011-04-14 2:14 ` Eric Dumazet
2011-04-14 21:10 ` Christoph Lameter
2011-04-14 21:15 ` Tejun Heo
2011-04-15 17:37 ` Christoph Lameter
2011-04-15 18:27 ` Tejun Heo
2011-04-15 19:43 ` Christoph Lameter
2011-04-15 23:52 ` Tejun Heo
2011-04-18 14:38 ` Christoph Lameter
2011-04-21 14:43 ` Tejun Heo
2011-04-21 14:58 ` Tejun Heo
2011-04-21 17:50 ` Christoph Lameter
2011-04-21 18:01 ` Tejun Heo
2011-04-21 18:20 ` Christoph Lameter
2011-04-21 18:37 ` Tejun Heo
2011-04-21 18:54 ` Christoph Lameter
2011-04-21 19:08 ` Tejun Heo
2011-04-22 2:33 ` Shaohua Li
2011-04-26 12:10 ` Tejun Heo
2011-04-26 19:02 ` Hugh Dickins
2011-04-27 10:28 ` Tejun Heo
2011-04-27 5:43 ` Shaohua Li
2011-04-27 10:20 ` Tejun Heo
2011-04-28 3:28 ` Shaohua Li
2011-04-28 10:09 ` Tejun Heo
2011-04-28 14:11 ` Christoph Lameter
2011-04-28 14:23 ` Tejun Heo
2011-04-28 14:30 ` Tejun Heo
2011-04-28 14:58 ` Christoph Lameter
2011-04-28 14:42 ` Christoph Lameter
2011-04-28 14:44 ` Tejun Heo [this message]
2011-04-28 14:52 ` Christoph Lameter
2011-04-28 14:56 ` Tejun Heo
2011-04-28 15:05 ` Christoph Lameter
2011-04-28 15:12 ` Tejun Heo
2011-04-28 15:22 ` Christoph Lameter
2011-04-28 15:31 ` Tejun Heo
2011-04-28 15:40 ` Tejun Heo
2011-04-28 15:47 ` Christoph Lameter
2011-04-28 15:48 ` Eric Dumazet
2011-04-28 15:59 ` Eric Dumazet
2011-04-28 16:17 ` Christoph Lameter
2011-04-28 16:35 ` Eric Dumazet
2011-04-28 16:52 ` Christoph Lameter
2011-04-28 16:59 ` Eric Dumazet
2011-04-29 8:52 ` Tejun Heo
2011-04-29 8:32 ` Shaohua Li
2011-04-29 8:19 ` Shaohua Li
2011-04-29 8:44 ` Tejun Heo
2011-04-29 14:02 ` Christoph Lameter
2011-04-29 14:03 ` Christoph Lameter
2011-04-29 14:18 ` Tejun Heo
2011-04-29 14:25 ` Christoph Lameter
2011-04-29 14:43 ` Tejun Heo
2011-04-29 14:55 ` Christoph Lameter
2011-05-05 4:08 ` Shaohua Li
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