Re: [lkp] [sched/fair] 98d8fd8126: -20.8% hackbench.throughput

From: Huang\, Ying
Date: Tue Oct 13 2015 - 21:48:56 EST


Dietmar Eggemann <dietmar.eggemann@xxxxxxx> writes:

> Hi Ying,
>
> On 24/09/15 03:00, kernel test robot wrote:
>> FYI, we noticed the below changes on
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core
>> commit 98d8fd8126676f7ba6e133e65b2ca4b17989d32c ("sched/fair: Initialize task load and utilization before placing task on rq")
>>
>>
>> =========================================================================================
>> tbox_group/testcase/rootfs/kconfig/compiler/nr_threads/mode/ipc:
>> lkp-ws02/hackbench/debian-x86_64-2015-02-07.cgz/x86_64-rhel/gcc-4.9/1600%/process/pipe
>>
>> commit:
>> 231678b768da07d19ab5683a39eeb0c250631d02
>> 98d8fd8126676f7ba6e133e65b2ca4b17989d32c
>>
>> 231678b768da07d1 98d8fd8126676f7ba6e133e65b
>> ---------------- --------------------------
>> %stddev %change %stddev
>> \ | \
>> 188818 Â 1% -20.8% 149585 Â 1% hackbench.throughput
>
> [...]
>
>>
>> lkp-ws02: Westmere-EP
>> Memory: 16G
>>
>>
>>
>>
>> hackbench.time.involuntary_context_switches
>>
>> 3e+08 ++------------------------O---------------------------------------+
>> O O O O O |
>> 2.5e+08 ++ O O O O O
>> | O O O O |
>> | O O O O |
>> 2e+08 ++ O |
>> | O |
>> 1.5e+08 ++ |
>> | |
>> 1e+08 ++ |
>> | .*...*..*..*...*..* |
>> *..*...*..*..*...*.. .*.. ..*..*. |
>> 5e+07 ++ *. *. |
>> | |
>> 0 ++----------------------------------------------------------------+
>>
>> vmstat.system.in
>>
>> 300000 ++-----------------------------------------------------------------+
>> | O O O |
>> O O O O O |
>> 250000 ++ O O O O
>> | O |
>> | O O O O O O |
>> 200000 ++ O O |
>> | |
>> 150000 ++ |
>> | |
>> | |
>> 100000 ++ |
>> | .*... .*..*...*..*..*...* |
>> *..*...*..*. *.. .*... .*...*. |
>> 50000 ++------------------*------*---------------------------------------+
>>
>> [*] bisect-good sample
>> [O] bisect-bad sample
>>
>> To reproduce:
>>
>> git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
>> cd lkp-tests
>> bin/lkp install job.yaml # job file is attached in this email
>> bin/lkp run job.yaml
>
> I try to recreate this on one of my Intel machines (Xeon CPU E5-2650 v2
> @ 2.60GHz) w/ 16 logical cpus. We haven't seen anything near a 20%
> performance degradation for hackbench when we were running our hackbench
> tests on 5/6 core arm machines as well as on a IVB-EP (2*10*2) Intel
> machine.
>
> So I cloned the repo:
>
> # git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg
> /lkp-tests.git lkp-tests
>
> and ran the hackbench example:
>
> root # lkp install $LKP_SRC/jobs/hackbench.yaml
>
> root # lkp split-job $LKP_SRC/jobs/hackbench.yaml
>
> root # lkp run ./hackbench-50%-threads-socket.yaml
>
> 2015-10-12 19:27:20 /usr/bin/hackbench -g 8 --threads -l 60000
> Running in threaded mode with 8 groups using 40 file descriptors each
> (== 320 tasks)
> Each sender will pass 60000 messages of 100 bytes
> ...
> wait for background monitors: perf-profile uptime proc-vmstat proc-stat
> meminfo slabinfo interrupts softirqs diskstats cpuidle turbostat sched_debug
>
> root # lkp result hackbench
>
> /result/hackbench/50%-threads-socket-50/$MACHINE/ubuntu/defconfig/gcc-4.8/3.16.0-50-generic/0/

There is a 'stats.json' file in this directory, where you can find your
test result.

> But I can't get any statistics out of it?
>
> root # lkp stat hackbench
> runs sum average stddev% case

You need to specify more option for 'lkp stat', please take a look at
'lkp stat -h' help message.

Best Regards,
Huang, Ying

> Thanks for your help in advance!
>
> -- Dietmar
>
> [...]
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