Re: [PATCH RFC] locking/mutexes: don't spin on owner when wait list is not NULL.

["Huang\, Ying" <ying.huang@intel.com>]

huang ying <huang.ying.caritas@gmail.com> writes:

> On Sat, Jan 30, 2016 at 9:18 AM, Ding Tianhong <dingtianhong@huawei.com> wrote:
>> On 2016/1/29 17:53, Peter Zijlstra wrote:
>>> On Sun, Jan 24, 2016 at 04:03:50PM +0800, Ding Tianhong wrote:
>>>
>>>> looks good to me, I will try this solution and report the result, thanks everyone.
>>>
>>> Did you get a change to run with this?
>>>
>>> .
>>>
>>
>> I backport this patch to 3.10 lts kernel, and didn't change any
>> logic, Till now, the patch works fine to me, and no need to change
>> anything,
>> So I think this patch is no problem, could you formal release this patch to the latest kernel? :)
>>
>> Thanks.
>> Ding
>>
>>
>
> The original patch from Tianhong triggered a performance regression
> because the optimistic spinning is turned off in effect.  I tested
> Peter's patch with same configuration and there show no regression.
> So I think the patch keep the optimistic spinning.  Test result
> details will be in the next email.

Here is the detailed test result:

=========================================================================================
compiler/cpufreq_governor/kconfig/nr_task/rootfs/tbox_group/test/testcase:
  gcc-4.9/performance/x86_64-rhel/100%/debian-x86_64-2015-02-07.cgz/lkp-ivb-d01/fstime/unixbench

commit: 
  v4.4
  1db66c17114d5437c0757d6792c0d8923192ecd6

            v4.4 1db66c17114d5437c0757d6792 
---------------- -------------------------- 
         %stddev     %change         %stddev
             \          |                \  
    371269 ± 10%     -93.2%      25080 ±  4%  unixbench.time.voluntary_context_switches
    371269 ± 10%     -93.2%      25080 ±  4%  time.voluntary_context_switches
      6189 ±  8%     -76.4%       1463 ±  6%  vmstat.system.cs
      5706 ±  0%      -1.7%       5608 ±  0%  vmstat.system.in
    113680 ± 12%     -73.5%      30086 ±  1%  cpuidle.C1-IVB.usage
   1515925 ± 20%     +68.3%    2552001 ± 11%  cpuidle.C1E-IVB.time
   1227221 ± 20%     -51.7%     592695 ± 17%  cpuidle.C3-IVB.time
      2697 ± 10%     -77.8%     598.33 ± 10%  cpuidle.C3-IVB.usage
     15173 ±  6%     -23.1%      11663 ±  1%  cpuidle.C6-IVB.usage
     34.38 ± 27%     -35.0%      22.33 ±  2%  cpuidle.POLL.usage
     61.92 ±  9%     +14.3%      70.78 ±  7%  sched_debug.cfs_rq:/.load_avg.min
     40.85 ± 29%     +27.3%      52.00 ± 10%  sched_debug.cfs_rq:/.runnable_load_avg.2
     -1949 ±-37%     -64.6%    -690.19 ±-134%  sched_debug.cfs_rq:/.spread0.4
     -1773 ±-29%     -85.6%    -256.00 ±-388%  sched_debug.cfs_rq:/.spread0.7
     -2478 ±-26%     -49.5%      -1251 ±-66%  sched_debug.cfs_rq:/.spread0.min
     61.95 ±  9%     +14.8%      71.11 ±  7%  sched_debug.cfs_rq:/.tg_load_avg_contrib.min
    396962 ± 12%     +27.9%     507573 ± 10%  sched_debug.cpu.avg_idle.0
    432973 ± 18%     +45.3%     629147 ± 12%  sched_debug.cpu.avg_idle.6
    448566 ±  3%     +11.5%     499990 ±  0%  sched_debug.cpu.avg_idle.avg
     45.31 ±  5%      -9.5%      41.00 ±  3%  sched_debug.cpu.cpu_load[3].7
     52204 ± 10%     -49.9%      26173 ± 34%  sched_debug.cpu.nr_switches.0
     50383 ± 12%     -57.6%      21353 ± 15%  sched_debug.cpu.nr_switches.1
     45425 ± 16%     -68.5%      14325 ± 28%  sched_debug.cpu.nr_switches.2
     43069 ± 20%     -65.5%      14852 ± 41%  sched_debug.cpu.nr_switches.3
     40285 ± 16%     -70.4%      11905 ± 47%  sched_debug.cpu.nr_switches.4
     40732 ± 13%     -75.8%       9872 ± 39%  sched_debug.cpu.nr_switches.5
     43011 ± 19%     -80.0%       8607 ± 42%  sched_debug.cpu.nr_switches.6
     38076 ± 12%     -75.9%       9167 ± 40%  sched_debug.cpu.nr_switches.7
     44148 ±  7%     -67.1%      14532 ±  6%  sched_debug.cpu.nr_switches.avg
     59877 ±  8%     -51.3%      29146 ± 21%  sched_debug.cpu.nr_switches.max
     33672 ±  9%     -83.0%       5718 ±  4%  sched_debug.cpu.nr_switches.min
     -0.62 ±-1411%   -2212.5%      13.00 ± 16%  sched_debug.cpu.nr_uninterruptible.0
     -1.23 ±-582%   -1318.8%      15.00 ± 35%  sched_debug.cpu.nr_uninterruptible.1
      2.54 ±263%    +267.7%       9.33 ± 91%  sched_debug.cpu.nr_uninterruptible.2
      0.31 ±2966%   -5841.7%     -17.67 ±-19%  sched_debug.cpu.nr_uninterruptible.5
      9.84 ± 19%     +70.4%      16.76 ±  5%  sched_debug.cpu.nr_uninterruptible.stddev
    116287 ±  4%     -20.9%      91972 ±  9%  sched_debug.cpu.sched_count.0
     50411 ± 12%     -57.6%      21382 ± 15%  sched_debug.cpu.sched_count.1
     45453 ± 16%     -68.4%      14356 ± 28%  sched_debug.cpu.sched_count.2
     43098 ± 20%     -65.5%      14888 ± 41%  sched_debug.cpu.sched_count.3
     40314 ± 16%     -70.4%      11934 ± 47%  sched_debug.cpu.sched_count.4
     40761 ± 13%     -75.7%       9896 ± 39%  sched_debug.cpu.sched_count.5
     43041 ± 19%     -79.9%       8636 ± 42%  sched_debug.cpu.sched_count.6
     38105 ± 12%     -75.9%       9193 ± 40%  sched_debug.cpu.sched_count.7
     52184 ±  6%     -56.3%      22782 ±  4%  sched_debug.cpu.sched_count.avg
    116288 ±  4%     -20.9%      91972 ±  9%  sched_debug.cpu.sched_count.max
     33701 ±  9%     -82.9%       5746 ±  4%  sched_debug.cpu.sched_count.min
     22760 ± 10%     -63.0%       8418 ± 40%  sched_debug.cpu.sched_goidle.0
     23319 ± 13%     -60.9%       9114 ± 22%  sched_debug.cpu.sched_goidle.1
     21273 ± 17%     -80.4%       4169 ± 13%  sched_debug.cpu.sched_goidle.2
     19993 ± 19%     -67.8%       6429 ± 45%  sched_debug.cpu.sched_goidle.3
     18614 ± 17%     -85.0%       2788 ± 29%  sched_debug.cpu.sched_goidle.4
     18921 ± 12%     -86.7%       2520 ± 15%  sched_debug.cpu.sched_goidle.5
     20131 ± 17%     -82.1%       3596 ± 52%  sched_debug.cpu.sched_goidle.6
     17861 ± 12%     -86.9%       2334 ± 14%  sched_debug.cpu.sched_goidle.7
     20359 ±  8%     -75.8%       4921 ±  5%  sched_debug.cpu.sched_goidle.avg
     26477 ± 10%     -60.2%      10539 ± 21%  sched_debug.cpu.sched_goidle.max
     15845 ± 10%     -87.2%       2033 ±  4%  sched_debug.cpu.sched_goidle.min
     29043 ± 15%     -58.8%      11958 ± 26%  sched_debug.cpu.ttwu_count.0
     24191 ± 10%     -68.8%       7547 ± 27%  sched_debug.cpu.ttwu_count.1
     21313 ± 11%     -72.7%       5819 ± 24%  sched_debug.cpu.ttwu_count.2
     21487 ± 13%     -61.4%       8296 ± 43%  sched_debug.cpu.ttwu_count.3
     19644 ± 15%     -54.4%       8967 ± 79%  sched_debug.cpu.ttwu_count.4
     20786 ± 15%     -69.2%       6409 ± 58%  sched_debug.cpu.ttwu_count.5
     20435 ± 17%     -79.3%       4231 ± 58%  sched_debug.cpu.ttwu_count.6
     19293 ± 17%     -77.0%       4432 ± 55%  sched_debug.cpu.ttwu_count.7
     22024 ±  7%     -67.3%       7207 ±  6%  sched_debug.cpu.ttwu_count.avg
     31009 ±  9%     -45.2%      17008 ± 17%  sched_debug.cpu.ttwu_count.max
     16791 ± 10%     -85.1%       2494 ±  5%  sched_debug.cpu.ttwu_count.min
      3084 ±  8%     +25.5%       3870 ±  9%  sched_debug.cpu.ttwu_local.avg

The URL of the original regression report email:

https://lists.01.org/pipermail/lkp/2016-January/003442.html

Best Regards,
Huang, Ying