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Message-ID: <f20c8c30-1379-4706-b980-73d2f7e5912a@arm.com>
Date:   Thu, 30 Nov 2023 12:53:30 +0000
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Subject: Re: [PATCH 0/2] Simplify Util_est
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To:     Vincent Guittot <vincent.guittot@linaro.org>
Cc:     hongyan.xia2@arm.com, mingo@redhat.com, alexs@kernel.org,
        linux-kernel@vger.kernel.org, vschneid@redhat.com,
        bristot@redhat.com, bsegall@google.com, rostedt@goodmis.org,
        dietmar.eggemann@arm.com, peterz@infradead.org,
        juri.lelli@redhat.com, mgorman@suse.de, corbet@lwn.net,
        siyanteng@loongson.cn, qyousef@layalina.io,
        linux-doc@vger.kernel.org
References: <20231127143238.1216582-1-vincent.guittot@linaro.org>
From:   Lukasz Luba <lukasz.luba@arm.com>
In-Reply-To: <20231127143238.1216582-1-vincent.guittot@linaro.org>
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Hi Vincent,

On 11/27/23 14:32, Vincent Guittot wrote:
> Following comment in [1], I prepared a patch to remove UTIL_EST_FASTUP.
> This enables us to simplify util_est behavior as proposed in patch 2.
> 
> [1] https://lore.kernel.org/lkml/CAKfTPtCAZWp7tRgTpwJmyEAkyN65acmYrfu9naEUpBZVWNTcQA@mail.gmail.com/
> 
> Vincent Guittot (2):
>    sched/fair: Remove SCHED_FEAT(UTIL_EST_FASTUP, true)
>    sched/fair: Simplify util_est
> 
>   Documentation/scheduler/schedutil.rst |  7 +--
>   include/linux/sched.h                 | 35 ++----------
>   kernel/sched/debug.c                  |  7 +--
>   kernel/sched/fair.c                   | 81 ++++++++++-----------------
>   kernel/sched/features.h               |  1 -
>   kernel/sched/pelt.h                   |  4 +-
>   6 files changed, 43 insertions(+), 92 deletions(-)
> 

I recovered my pixel6 and applied these changes.
No power regression in Jankbench. No performance regression in GB5.
Better score in Chrome running Speedometer +3..5%.

The code looks much more clean, without the 'struct util_est'
(we will have to adjust our trace events to that change but it's worth).

Also, I was a bit surprised that the UTIL_EST_FASTUP wasn't helping
that much comparing to that new 'runnable' signal for the
underestimation corner case...

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