Re: [PATCH 0/10 v2] sched/fair: Fix statistics with delayed dequeue
From: Mike Galbraith
Date: Sun Dec 01 2024 - 08:30:40 EST
Greetings,
On Fri, 2024-11-29 at 17:17 +0100, Vincent Guittot wrote:
> Delayed dequeued feature keeps a sleeping sched_entitiy enqueued until its
> lag has elapsed. As a result, it stays also visible in the statistics that
> are used to balance the system and in particular the field h_nr_running.
>
> This serie fixes those metrics by creating a new h_nr_queued that tracks
> all queued tasks. It renames h_nr_running into h_nr_runnable and restores
> the behavior of h_nr_running i.e. tracking the number of fair tasks that
> want to run.
>
> h_nr_runnable is used in several places to make decision on load balance:
> - PELT runnable_avg
> - deciding if a group is overloaded or has spare capacity
> - numa stats
> - reduced capacity management
> - load balance between groups
I took the series for a spin in tip v6.12-10334-gb1b238fba309, but
runnable seems to have an off-by-one issue, causing it to wander ever
further south.
patches 1-3 applied.
.h_nr_runnable : -3046
.runnable_avg : 450189777126
full set applied.
.h_nr_runnable : -5707
.runnable_avg : 4391793519526
-Mike