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Date:   Tue, 5 Oct 2021 11:41:02 +0200
From:   Peter Zijlstra <>
To:     Mel Gorman <>
Cc:     Vincent Guittot <>,
        Mike Galbraith <>, Ingo Molnar <>,
        Valentin Schneider <>,
        Aubrey Li <>,
        Barry Song <>,
        Srikar Dronamraju <>,
        LKML <>
Subject: Re: [PATCH 2/2] sched/fair: Scale wakeup granularity relative to

On Wed, Sep 22, 2021 at 04:04:57PM +0100, Mel Gorman wrote:
> On Wed, Sep 22, 2021 at 04:15:27PM +0200, Vincent Guittot wrote:

> The reason I used SCHED_TUNABLESCALING_NONE for the changelog is that
> the exact values depend on the number of CPUs so values are not even
> the same across the range of machines I'm using. sysctl_sched_latency,
> sysctl_sched_min_granularity sysctl_sched_wakeup_granularity are all
> scaled but the ratios remain constant.

It might make sense to reconsider the whole scaling thing FWIW. It used
to be that desktop systems had 'small' number of CPUs (<=8) and servers
had more.

But today it's not uncommon to have 32-64 CPUs in a desktop system. And
even LOG scaling gets us into stupid numbers for the latencies.

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