linux-kernel - [PATCH v2 0/5] sched: Cleanup and improve polling idle loops

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Date:	Wed,  4 Jun 2014 10:31:13 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Peter Zijlstra <peterz@...radead.org>, umgwanakikbuti@...il.com
Cc:	mingo@...nel.org, tglx@...utronix.de, nicolas.pitre@...aro.org,
	daniel.lezcano@...aro.org, linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>
Subject: [PATCH v2 0/5] sched: Cleanup and improve polling idle loops

This series reduces the number of IPIs on my workload by something like
99%.  It's down from many hundreds per second to very few.

The basic idea behind this series is to make TIF_POLLING_NRFLAG be a
reliable indication that the idle task is polling.  Once that's done,
the rest is reasonably straightforward.

Patches 1 and 2 are related improvements: patch 1 teaches the cpuidle
polling loop how to poll, and patch 2 adds tracepoints so that avoided
IPIs are visible.  Patch 3 is the main semantic change, patch 4 is
cleanup, and patch 5 is peterz's code, rebased on top of my stuff, and
fixed up a bit.

Changes from v1:

 - Squashed the two idle loop rearrangement patches.
 - Improved comments.

Andy Lutomirski (4):
  cpuidle: Set polling in poll_idle
  sched,trace: Add a tracepoint for IPI-less remote wakeups
  sched,idle: Clear polling before descheduling the idle thread
  sched,idle: Simplify wake_up_idle_cpu

Peter Zijlstra (1):
  sched: Optimize ttwu IPI

 drivers/cpuidle/driver.c     |  7 ++--
 include/trace/events/sched.h | 20 +++++++++++
 kernel/sched/core.c          | 79 +++++++++++++++++++++++++++++---------------
 kernel/sched/idle.c          | 30 ++++++++++++++++-
 kernel/sched/sched.h         |  6 ++++
 5 files changed, 113 insertions(+), 29 deletions(-)

-- 
1.9.3

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