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Subject: Re: [PATCH v2 1/2] sched/fair: Only compute base_energy_pd if
 necessary
To:     Pierre.Gondois@arm.com
Cc:     linux-kernel@vger.kernel.org, xuewen.yan@unisoc.com,
        qperret@qperret.net, dietmar.eggemann@arm.com,
        Vincent.Donnefort@arm.com, mingo@redhat.com, peterz@infradead.org,
        juri.lelli@redhat.com, vincent.guittot@linaro.org,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com
References: <20210429101948.31224-1-Pierre.Gondois@arm.com>
 <20210429101948.31224-2-Pierre.Gondois@arm.com>
From:   Lukasz Luba <lukasz.luba@arm.com>
Message-ID: <c7dba0eb-9e82-06ff-299c-aa3fc28c1107@arm.com>
Date:   Fri, 30 Apr 2021 12:03:56 +0100
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Hi Pierre,

On 4/29/21 11:19 AM, Pierre.Gondois@arm.com wrote:
> From: Pierre Gondois <Pierre.Gondois@arm.com>
> 
> find_energy_efficient_cpu() searches the best energy CPU
> to place a task on. To do so, the energy of each performance domain
> (pd) is computed w/ and w/o the task placed in each pd.
> 
> The energy of a pd w/o the task (base_energy_pd) is computed prior
> knowing whether a CPU is available in the pd.
> 
> Move the base_energy_pd computation after looping through the CPUs
> of a pd and only computes it if at least one CPU is available.
> 
> Suggested-by: Xuewen Yan <xuewen.yan@unisoc.com>
> Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
> ---
>   kernel/sched/fair.c | 38 ++++++++++++++++++++++----------------
>   1 file changed, 22 insertions(+), 16 deletions(-)
> 

Make sense. I will speed-up feec() on Android devices for tasks
being moved into 'background' cgroup (limited to subset of CPUs,
e.g. to only Little cores). LGTM.

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

Regards,
Lukasz