linux-kernel - Re: [External] Re: [PATCH v2 06/10] sched/fair: delete superfluous SKIP_AGE

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Message-ID: <7b611f83-87ab-30aa-beb1-94f2f3110f47@bytedance.com>
Date:   Thu, 14 Jul 2022 21:24:24 +0800
From:   Chengming Zhou <zhouchengming@...edance.com>
To:     Dietmar Eggemann <dietmar.eggemann@....com>, mingo@...hat.com,
        peterz@...radead.org, vincent.guittot@...aro.org,
        rostedt@...dmis.org, bsegall@...gle.com, vschneid@...hat.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH v2 06/10] sched/fair: delete superfluous
 SKIP_AGE_LOAD

On 2022/7/14 20:33, Dietmar Eggemann wrote:
> On 13/07/2022 06:04, Chengming Zhou wrote:
>> There are three types of attach_entity_cfs_rq():
>>
>> 1. task migrate to CPU
>> 2. task move to cgroup
>> 3. task switched to fair from !fair
>>
>> The case1 and case2 already have sched_avg last_update_time
>> reset to 0 when attach_entity_cfs_rq().
>>
>> We will make case3 also have last_update_time reset to 0 when
>> attach_entity_cfs_rq() in the following patches.
>>
>> So it makes no difference whether SKIP_AGE_LOAD is set or not.
> 
> Wouldn't this patch make more sense after 09/10?
> 

Yes, this patch was put at last in the v1.

In this v2, the following patch 07/10 make attach_entity_cfs_rq() to use
update_load_avg(DO_ATTACH) to do conditional attach.

So I want to get rid of "sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD"
earlier in this patch, or have to write like this:


  int flags = UPDATE_TG | DO_ATTACH;

  update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? flags : SKIP_AGE_LOAD | flags);


Thanks.

> [...]