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Re: [PATCH -v2 04/18] sched/fair: Remove se->load.weight from se->avg.load_sum

From Morten Rasmussen <morten.rasmussen@arm.com>
Newsgroups linux.kernel
Subject Re: [PATCH -v2 04/18] sched/fair: Remove se->load.weight from se->avg.load_sum
Date 2017-09-29 17:30 +0200
Message-ID <uv5oK-7Wg-19@gated-at.bofh.it> (permalink)
References <ukUkV-5wR-5@gated-at.bofh.it> <ukUuB-5EI-5@gated-at.bofh.it>
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On Fri, Sep 01, 2017 at 03:21:03PM +0200, Peter Zijlstra wrote:
> +/*
> + * sched_entity:
> + *
> + *   load_sum := runnable_sum
> + *   load_avg = se_weight(se) * runnable_avg
> + *
> + * cfq_rs:

I think this should be "cfs_rq" instead.

> + *
> + *   load_sum = \Sum se_weight(se) * se->avg.load_sum
> + *   load_avg = \Sum se->avg.load_avg
> + */

I find it a bit confusing that load_sum and load_avg have different
definitions, but I guess I will discover why dropping weight from
se->avg.load_sum helps a bit later. We can't do the same for cfs_rq as
it is a \Sum of sums where we add/remove contributions when tasks
migrate.

Have we defined the relation between runnable_sum and runnable_avg in a
comment somewhere already? Otherwise it might be helpful to add. It is
in the code of course :-)

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Re: [PATCH -v2 04/18] sched/fair: Remove se->load.weight from  se->avg.load_sum Morten Rasmussen <morten.rasmussen@arm.com> - 2017-09-29 17:30 +0200
  Re: [PATCH -v2 04/18] sched/fair: Remove se->load.weight from  se->avg.load_sum Peter Zijlstra <peterz@infradead.org> - 2017-09-29 18:40 +0200

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