linux-kernel - Re: [PATCH] cpuidle: menu: Cleanup after loadavg removal

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Message-ID: <CAJZ5v0jU4A6mdrnzXde1TEvKnVYHg2ONa5hkKy8Oiy8izKAhag@mail.gmail.com>
Date: Fri, 7 Jun 2024 20:56:08 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Christian Loehle <christian.loehle@....com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	linux-pm@...r.kernel.org, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpuidle: menu: Cleanup after loadavg removal

On Tue, Jun 4, 2024 at 12:55 PM Christian Loehle
<christian.loehle@....com> wrote:
>
> The performance impact of loadavg was removed with commit a7fe5190c03f
> ("cpuidle: menu: Remove get_loadavg() from the performance multiplier")
> With only iowait remaining the description can be simplified, remove
> also the no longer needed includes.
>
> Signed-off-by: Christian Loehle <christian.loehle@....com>
> ---
>  drivers/cpuidle/governors/menu.c | 17 +++++------------
>  1 file changed, 5 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index b96e3da0fedd..783b5d1dacdc 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -14,8 +14,6 @@
>  #include <linux/ktime.h>
>  #include <linux/hrtimer.h>
>  #include <linux/tick.h>
> -#include <linux/sched.h>
> -#include <linux/sched/loadavg.h>
>  #include <linux/sched/stat.h>
>  #include <linux/math64.h>
>
> @@ -95,16 +93,11 @@
>   * state, and thus the less likely a busy CPU will hit such a deep
>   * C state.
>   *
> - * Two factors are used in determing this multiplier:
> - * a value of 10 is added for each point of "per cpu load average" we have.
> - * a value of 5 points is added for each process that is waiting for
> - * IO on this CPU.
> - * (these values are experimentally determined)
> - *
> - * The load average factor gives a longer term (few seconds) input to the
> - * decision, while the iowait value gives a cpu local instantanious input.
> - * The iowait factor may look low, but realize that this is also already
> - * represented in the system load average.
> + * Currently there is only one value determining the factor:
> + * 10 points are added for each process that is waiting for IO on this CPU.
> + * (This value was experimentally determined.)
> + * Utilization is no longer a factor as it was shown that it never contributed
> + * significantly to the performance multiplier in the first place.
>   *
>   */
>
> --

Applied as 6.11 material, thanks!