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Date:   Wed, 19 Feb 2020 14:02:17 +0000
From:   Mel Gorman <mgorman@techsingularity.net>
To:     Vincent Guittot <vincent.guittot@linaro.org>
Cc:     mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        mgorman@suse.de, linux-kernel@vger.kernel.org, pauld@redhat.com,
        parth@linux.ibm.com, valentin.schneider@arm.com, hdanton@sina.com
Subject: Re: [PATCH v3 4/5] sched/pelt: Add a new runnable average signal
Message-ID: <20200219140216.GP3466@techsingularity.net>
References: <20200214152729.6059-5-vincent.guittot@linaro.org>
 <20200219125513.8953-1-vincent.guittot@linaro.org>
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On Wed, Feb 19, 2020 at 01:55:13PM +0100, Vincent Guittot wrote:
> Now that runnable_load_avg has been removed, we can replace it by a new
> signal that will highlight the runnable pressure on a cfs_rq. This signal
> track the waiting time of tasks on rq and can help to better define the
> state of rqs.
> 
> At now, only util_avg is used to define the state of a rq:
>   A rq with more that around 80% of utilization and more than 1 tasks is
>   considered as overloaded.
> 
> But the util_avg signal of a rq can become temporaly low after that a task
> migrated onto another rq which can bias the classification of the rq.
> 
> When tasks compete for the same rq, their runnable average signal will be
> higher than util_avg as it will include the waiting time and we can use
> this signal to better classify cfs_rqs.
> 
> The new runnable_avg will track the runnable time of a task which simply
> adds the waiting time to the running time. The runnable _avg of cfs_rq
> will be the /Sum of se's runnable_avg and the runnable_avg of group entity
> will follow the one of the rq similarly to util_avg.
> 
> Tested-by: Valentin Schneider <valentin.schneider@arm.com>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

Thanks.

Picked up and included in "Reconcile NUMA balancing decisions with the
load balancer v4". The only change I made to your patches was move the
reintroduction of cpu_runnable to the patch that requires it to avoid a
build warning.

-- 
Mel Gorman
SUSE Labs