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Date: Sun, 15 Dec 2013 16:17:54 +0000
From: Mel Gorman <mgorman@suse.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alex Shi <alex.shi@linaro.org>, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Fengguang Wu <fengguang.wu@intel.com>, H Peter Anvin <hpa@zytor.com>,
        Linux-X86 <x86@kernel.org>, Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] Fix ebizzy performance regression due to X86 TLB
 range flush v2
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On Sun, Dec 15, 2013 at 03:55:39PM +0000, Mel Gorman wrote:
> <SNIP>
> tlbflush micro benchmark
>                     3.13.0-rc3            3.13.0-rc3                3.4.69
>                        vanilla           nowalk-v2r7               vanilla
> Min    1        7.00 (  0.00%)        6.00 ( 14.29%)        5.00 ( 28.57%)
> Min    2        8.00 (  0.00%)        6.00 ( 25.00%)        4.00 ( 50.00%)
> Min    3       13.00 (  0.00%)       11.00 ( 15.38%)        9.00 ( 30.77%)
> Min    4       17.00 (  0.00%)       19.00 (-11.76%)       15.00 ( 11.76%)
> Mean   1       11.28 (  0.00%)       10.66 (  5.48%)        5.17 ( 54.13%)
> Mean   2       11.42 (  0.00%)       11.52 ( -0.85%)        9.04 ( 20.82%)
> Mean   3       23.43 (  0.00%)       21.64 (  7.64%)       10.92 ( 53.39%)
> Mean   4       35.33 (  0.00%)       34.17 (  3.28%)       19.55 ( 44.67%)
> Range  1        6.00 (  0.00%)        7.00 (-16.67%)        4.00 ( 33.33%)
> Range  2       23.00 (  0.00%)       36.00 (-56.52%)       19.00 ( 17.39%)
> Range  3       15.00 (  0.00%)       17.00 (-13.33%)       10.00 ( 33.33%)
> Range  4       29.00 (  0.00%)       26.00 ( 10.34%)        9.00 ( 68.97%)
> Stddev 1        1.01 (  0.00%)        1.12 ( 10.53%)        0.57 (-43.70%)
> Stddev 2        1.83 (  0.00%)        3.03 ( 66.06%)        6.83 (274.00%)
> Stddev 3        2.82 (  0.00%)        3.28 ( 16.44%)        1.21 (-57.14%)
> Stddev 4        6.65 (  0.00%)        6.32 ( -5.00%)        1.58 (-76.24%)
> Max    1       13.00 (  0.00%)       13.00 (  0.00%)        9.00 ( 30.77%)
> Max    2       31.00 (  0.00%)       42.00 (-35.48%)       23.00 ( 25.81%)
> Max    3       28.00 (  0.00%)       28.00 (  0.00%)       19.00 ( 32.14%)
> Max    4       46.00 (  0.00%)       45.00 (  2.17%)       24.00 ( 47.83%)
> 
> <SNIP>
> 
>           3.13.0-rc3  3.13.0-rc3      3.4.69
>              vanilla nowalk-v2r7     vanilla
> User          179.36      165.25       97.29
> System        153.59      155.07      128.32
> Elapsed      1439.52     1437.69     2802.01
> 

After I ran the test, I looked closer at the elapsed times and it was
due to a bug in the test setup itself. The tlbflush tests will need to
be rerun but ebizzy still has the problem where threads see very
different performance.

-- 
Mel Gorman
SUSE Labs