Re: [lkp-robot] [sched, cpumask] 9475ceda45: -6% regression of hackbench.throughput

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

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Ye Xiaolong <xiaolong.ye@intel.com> writes:

> On 05/16, Peter Zijlstra wrote:
>>On Tue, May 16, 2017 at 09:33:49AM +0800, kernel test robot wrote:
>>> 
>>> Greeting,
>>> 
>>> We noticed a -6% regression of hackbench.throughput due to commit:
>>> 
>>> commit: 9475ceda453545fc55b2ccf30b1fbed0e590fdca ("sched,cpumask: Export for_each_cpu_wrap()")
>>> https://git.kernel.org/cgit/linux/kernel/git/peterz/queue.git schd/wip
>>> 
>>> in testcase: hackbench
>>> on test machine: 112 threads Skylake with 64G memory
>>
>>How many sockets does that have? 112 threads is 56 cores. With a 23 core
>>part that gives 2 sockets. But 23 is a very weird number of cores to
>>have on a part (also wikipedia doesn't yet list the SKX parts).
>>
>
> Hi, ying
>
> The tbox is lkp-skl-sp1, how do I get the socket info for it?

You can queue hwinfo.yaml for it and check lscpu result.

Best Regards,
Huang, Ying

> Thanks,
> Xiaolong
>
>
>>> with following parameters:
>>> 
>>> 	nr_threads: 50%
>>> 	mode: threads
>>> 	ipc: socket
>>> 	cpufreq_governor: performance
>>> 
>>> test-description: Hackbench is both a benchmark and a stress test for the Linux kernel scheduler.
>>> test-url: https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/sched/cfs-scheduler/hackbench.c
>>
>>> Details are as below:
>>> -------------------------------------------------------------------------------------------------->
>>> 
>>> 
>>> To reproduce:
>>> 
>>>         git clone https://github.com/01org/lkp-tests.git
>>>         cd lkp-tests
>>>         bin/lkp install job.yaml  # job file is attached in this email
>>>         bin/lkp run     job.yaml
>>> 
>>> testcase/path_params/tbox_group/run: hackbench/50%-threads-socket-performance/lkp-skl-sp1
>>> 
>>
>>> 
>>>                                 hackbench.throughput
>>> 
>>>   145000 ++-----------------------------------------------------------------+
>>>   140000 *+**.*.*               *. .**.*.*.**.*.**.*.**.*. *.*.**.      .*  |
>>>          |       *.*.**.*.**.*.*  *                       *       *.**.*  *.*
>>>   135000 ++                                                                 |
>>>   130000 ++                         O      OO O OO                          |
>>>          |              O OO   OO O  O O O                                  |
>>>   125000 ++                  O                                              |
>>>   120000 ++                                                                 |
>>>   115000 ++                                                                 |
>>>          |                                                                  |
>>>   110000 ++     O                                                           |
>>>   105000 ++                                                                 |
>>>          | O       O OO                                                     |
>>>   100000 O+ O O  O                                                          |
>>>    95000 ++-----------------------------------------------------------------+
>>
>>
>>So what is 'hackbench.throughput' and how do you run it? My hackbench
>>only gives a total time, like:
>>
>>$ perf bench sched messaging -g 50 -l 5000
>># Running 'sched/messaging' benchmark:
>># 20 sender and receiver processes per group
>># 50 groups == 2000 processes run
>>
>>     Total time: 5.302 [sec]
>>
>>
>>And my numbers are nowhere stable enough to conclusively see a
>>regression, but I can maybe see a 2% dip on my IVB-EP.
>>
>>And I so don't want to dig through your script mess again :/