Re: [PATCH 0/2] Simplify Util_est

[Lukasz Luba <lukasz.luba@arm.com>]

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>