linux-kernel - [RESEND][PATCH v3 0/1] Fix lb_imbalance reporting in /proc/schedstat

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Date: Tue, 14 May 2024 04:44:44 +0000
From: Swapnil Sapkal <swapnil.sapkal@....com>
To: <linux-kernel@...r.kernel.org>, <mingo@...hat.com>, <peterz@...radead.org>
CC: <torvalds@...ux-foundation.org>, <juri.lelli@...hat.com>,
	<dietmar.eggemann@....com>, <rostedt@...dmis.org>, <mgorman@...e.de>,
	<bristot@...hat.com>, <vschneid@...hat.com>, <vincent.guittot@...aro.org>,
	<gautham.shenoy@....com>, <sshegde@...ux.ibm.com>, <kprateek.nayak@....com>,
	Swapnil Sapkal <swapnil.sapkal@....com>
Subject: [RESEND][PATCH v3 0/1] Fix lb_imbalance reporting in /proc/schedstat

This patch adds new fields to /proc/schdstat. First version of
the patch is sent here [1]. This patch goes on top of the
commit d72cf62438d6 ("sched/balancing: Fix a couple of outdated function names in comments")
from tip/sched/core. This change is intended to be a part of v16 of
/proc/schedstat.

v2 --> v3 change:
  - Incorporated review comment by Shrikanth Hegde
  - Added reviewed by.

v1 --> v2 change:
  - Added links to previous schedstat documentation
  - Incorporated review comments by Shrikanth Hegde

Motivation:

In /proc/schedstat, lb_imbalance reports the sum of imbalances
discovered in sched domains with each call to sched_balance_rq(), which is
not very useful because lb_imbalance does not mention whether the imbalance
is due to load, utilization, nr_tasks or misfit_tasks. Remove this field
from /proc/schedstat.

Currently there is no field in /proc/schedstat to report different types
of imbalances. Introduce new fields in /proc/schedstat to report the
total imbalances in load, utilization, nr_tasks or misfit_tasks.

[1] https://lore.kernel.org/lkml/66f1e42c-9035-4f9b-8c77-976ab50638bd@amd.com/

Swapnil Sapkal (1):
  sched: Report the different kinds of imbalances in /proc/schedstat

 Documentation/scheduler/sched-stats.rst | 121 ++++++++++++++----------
 include/linux/sched/topology.h          |   5 +-
 kernel/sched/fair.c                     |  21 +++-
 kernel/sched/stats.c                    |   7 +-
 4 files changed, 99 insertions(+), 55 deletions(-)

-- 
2.34.1