From: 王贇 <yun.wang@linux.alibaba.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ben Segall <bsegall@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mel Gorman <mgorman@suse.de>,
"open list:SCHEDULER" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] sched: fix the nonsense shares when load of cfs_rq is too, small
Date: Fri, 6 Mar 2020 17:34:53 +0800 [thread overview]
Message-ID: <746d2b82-fb39-1412-0dc3-c5ff10b578ec@linux.alibaba.com> (raw)
In-Reply-To: <CAKfTPtD+He8UULUavz0csUeUV3TBdjShV9kUPQY6rpLswUAm4g@mail.gmail.com>
On 2020/3/6 下午4:04, Vincent Guittot wrote:
> On Fri, 6 Mar 2020 at 05:23, 王贇 <yun.wang@linux.alibaba.com> wrote:
>>
>>
>>
>> On 2020/3/5 下午3:53, Vincent Guittot wrote:
>>> On Thu, 5 Mar 2020 at 02:14, 王贇 <yun.wang@linux.alibaba.com> wrote:
>> [snip]
>>>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>>>>> index fcc968669aea..6d7a9d72d742 100644
>>>>> --- a/kernel/sched/fair.c
>>>>> +++ b/kernel/sched/fair.c
>>>>> @@ -3179,9 +3179,9 @@ static long calc_group_shares(struct cfs_rq *cfs_rq)
>>>>> long tg_weight, tg_shares, load, shares;
>>>>> struct task_group *tg = cfs_rq->tg;
>>>>>
>>>>> - tg_shares = READ_ONCE(tg->shares);
>>>>> + tg_shares = scale_load_down(READ_ONCE(tg->shares));
>>>>>
>>>>> - load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg);
>>>>> + load = max(cfs_rq->load.weight, scale_load(cfs_rq->avg.load_avg));
>>>>>
>>>>> tg_weight = atomic_long_read(&tg->load_avg);
>>>>
>>>> Get the point, but IMHO fix scale_load_down() sounds better, to
>>>> cover all the similar cases, let's first try that way see if it's
>>>> working :-)
>>>
>>> The problem with this solution is that the avg.load_avg of gse or
>>> cfs_rq might stay to 0 because it uses
>>> scale_load_down(se/cfs_rq->load.weight)
>>
>> Will cfs_rq->load.weight be zero too without scale down?
>
> cfs_rq->load.weight will never be 0, it's min is 2
>
>>
>> If cfs_rq->load.weight got at least something, the load will not be
>> zero after pick the max, correct?
>
> But the cfs_rq->avg.load_avg will never be other than 0 what ever
> there are heavy or light tasks in the group
Aha, get the point now :-)
BTW, would you like to give a review on
[PATCH] sched: avoid scale real weight down to zero
please?
Regards,
Michael Wang
>
>>
>> Regards,
>> Michael Wang
>>
>>>
>>>>
>>>> Regards,
>>>> Michael Wang
>>>>
>>>>>
>>>>>
>>>>>
next prev parent reply other threads:[~2020-03-06 9:35 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 14:17 [RFC PATCH] sched: fix the nonsense shares when load of cfs_rq is too, small 王贇
2020-03-03 19:52 ` Peter Zijlstra
2020-03-04 1:19 ` 王贇
2020-03-04 8:47 ` Vincent Guittot
2020-03-04 9:43 ` Vincent Guittot
2020-03-05 1:23 ` 王贇
2020-03-04 9:52 ` Peter Zijlstra
2020-03-04 11:55 ` Vincent Guittot
2020-03-05 1:08 ` 王贇
2020-03-04 8:45 ` Vincent Guittot
2020-03-04 18:47 ` bsegall
2020-03-05 1:14 ` 王贇
2020-03-05 7:53 ` Vincent Guittot
2020-03-06 4:23 ` 王贇
2020-03-06 8:04 ` Vincent Guittot
2020-03-06 9:34 ` 王贇 [this message]
2020-03-06 19:17 ` bsegall
2020-03-09 11:15 ` Vincent Guittot
2020-03-10 3:42 ` 王贇
2020-03-10 7:57 ` Vincent Guittot
2020-03-10 8:15 ` 王贇
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