On 10/10/16 19:29, Vincent Guittot wrote:
> On 10 October 2016 at 15:54, Dietmar Eggemann <dietmar.eggem...@arm.com>
> wrote:
>> On 10/10/16 13:29, Vincent Guittot wrote:
>>> On 10 October 2016 at 12:01, Matt Fleming <m...@codeblueprint.co.uk> wrote:
>>>> On Sun, 09 Oct, at 11:39:27AM, Wanpeng Li wrote:
[...]
>>> I have tried to reprocude your issue on my target an hikey board (ARM
>>> based octo cores) but i failed to see a regression with commit
>>> 7dc603c9028e. Neverthless, i can see tasks not been well spread
>>
>> Wasn't this about the two patches mentioned in this thread? The one from
>> Matt using 'se->sum_exec_runtime' in the if condition in
>> enqueue_entity_load_avg() and Peterz's conditional call to
>> update_rq_clock(rq) in enqueue_task()?
>
> I was trying to reproduce the regression that Matt mentioned at the
> beg of the thread not those linked to proposed fixes
OK.
>
>>
>>> during fork as you mentioned. So I have studied a bit more the
>>> spreading issue during fork last week and i have a new version of my
>>> proposed patch that i'm going to send soon. With this patch, i can see
>>> a good spread of tasks during the fork sequence and some kind of perf
>>> improvement even if it's bit difficult as the variance is quite
>>> important with hackbench test so it's mainly an improvement of
>>> repeatability of the result
>>
>> Hikey (ARM64 2x4 cpus) board: cpufreq: performance, cpuidle: disabled
>>
>> Performance counter stats for 'perf bench sched messaging -g 20 -l 500'
>> (10 runs):
>>
>> (1) tip/sched/core: commit 447976ef4fd0
>>
>> 5.902209533 seconds time elapsed ( +- 0.31% )
>
> This seems to be too long to test the impact of the forking phase of hackbench
[...]
Yeah, you're right. But I can't see any significant difference. IMHO,
it's all in the noise.
(A) Performance counter stats for 'perf bench sched messaging -g 100 -l
1 -t'
# 20 sender and receiver threads per group
# 100 groups == 4000 threads run
(1) tip/sched/core: commit 447976ef4fd0
Total time: 0.188 [sec]
(2) tip/sched/core + original patch on the 'sched/fair: Do not decay
new task load on first enqueue' thread (23/09/16)
Total time: 0.199 [sec]
(3) tip/sched/core + Peter's ENQUEUE_NEW patch on the 'sched/fair: Do
not decay new task load on first enqueue' thread (28/09/16)
Total time: 0.178 [sec]
(B) hackbench -P -g 1
Running in process mode with 1 groups using 40 file descriptors
each (== 40 tasks)
Each sender will pass 100 messages of 100 bytes
(1) 0.067
(2) 0.083
(3) 0.073
(C) hackbench -T -g 1
Running in threaded mode with 1 groups using 40 file descriptors
each (== 40 tasks)
Each sender will pass 100 messages of 100 bytes
(1) 0.077
(2) 0.079
(3) 0.072
Maybe, instead of the performance gov, I should pin the frequency to a
lower one to eliminate the thermal influence on this Hikey board.
