linux-kernel - Re: [percpu_counter] 74e72f894: -47.6% aim7 jobs-per-min

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Message-ID: <CACVXFVNRvPRXF9VL-b+0iGE9XETwmTZ-JEmdxRGdovRamLnaGQ@mail.gmail.com>
Date:	Fri, 17 Jan 2014 18:56:24 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	Fengguang Wu <fengguang.wu@...el.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: [percpu_counter] 74e72f894: -47.6% aim7 jobs-per-min

Hi Fengguang,

On Fri, Jan 17, 2014 at 6:20 PM, Fengguang Wu <fengguang.wu@...el.com> wrote:
> Ming Lei,
>
> We noticed that commit 74e72f894 ("lib/percpu_counter.c: fix
> __percpu_counter_add()") introduces -47.6% regression in aim7 brk_test
> on a 2S SNB server. Comparing to its parent commit:

The commit has a bug, could you apply Hugh's patch[1] to test if
the regression can be fixed?

If the performance regression is still there, it may be caused by bad
performance of this_cpu_add(), then I suggest you to test the patch[2]
too without enabling lockdep.


[1], http://marc.info/?t=138991497900001&r=1&w=2
[2], http://marc.info/?l=linux-kernel&m=138909074202090&w=2

Thanks,
-- 
Ming Lei
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