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

[Dietmar Eggemann]

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 ±  1%     -20.8%     149585 ±  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/

But I can't get any statistics out of it?

root # lkp stat hackbench
runs sum average stddev% case

Thanks for your help in advance!

-- Dietmar

[...]

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