Re: [PATCH v4 3/3] sched/fair: Introduce a CPU capacity comparison helper

From: Valentin Schneider
Date: Tue Apr 06 2021 - 11:59:32 EST


On 06/04/21 17:37, Dietmar Eggemann wrote:
> On 01/04/2021 21:30, Valentin Schneider wrote:
>> While at it, replace group_smaller_{min, max}_cpu_capacity() with
>> comparisons of the source group's min/max capacity and the destination
>> CPU's capacity.
>
> IMHO, you haven't mentioned why you replace local sched group with dst
> CPU. I can see that only the capacity of the dst CPU makes really sense
> here. Might be worth mentioning in the patch header why. There is some
> of it in v3 6/7 but that's a different change.
>

Right, some of it got lost in the shuffling. This was a separate change in
v1 (4/8). I can reuse that changelog into:

"""
Also note that comparing capacity extrema of local and source sched_group's
doesn't make much sense when at the day of the day the imbalance will be
pulled by a known env->dst_cpu, whose capacity can be anywhere within the
local group's capacity extrema.

While at it, replace group_smaller_{min, max}_cpu_capacity() with
comparisons of the source group's min/max capacity and the destination
CPU's capacity.
"""

> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
>
> [...]