linux-kernel - [PATCH v2 0/5] sched, timer: Improve scalability of itimers

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Message-Id: <1430251224-5764-1-git-send-email-jason.low2@hp.com>
Date:	Tue, 28 Apr 2015 13:00:19 -0700
From:	Jason Low <jason.low2@...com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Mike Galbraith <umgwanakikbuti@...il.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	Waiman Long <Waiman.Long@...com>,
	Aswin Chandramouleeswaran <aswin@...com>,
	Scott J Norton <scott.norton@...com>,
	Jason Low <jason.low2@...com>
Subject: [PATCH v2 0/5] sched, timer: Improve scalability of itimers

This patchset improves the scalability of itimers, thread_group_cputimer
and addresses a performance issue we found while running a database
workload where more than 30% of total time is spent in the kernel
trying to acquire the thread_group_cputimer spinlock.

While we're modifying sched and timer, patch 1 also updates all existing
usages of ACCESS_ONCE with the new READ_ONCE and WRITE_ONCE APIs in
those areas.

Jason Low (5):
  sched, timer: Remove usages of ACCESS_ONCE in the scheduler
  sched, numa: Document usages of mm->numa_scan_seq
  sched, timer: Use atomics in thread_group_cputimer to improve
    scalability
  sched, timer: Provide an atomic task_cputime data structure
  sched, timer: Use the atomic task_cputime in thread_group_cputimer

 include/linux/init_task.h      |    5 +-
 include/linux/sched.h          |   29 +++++++++----
 kernel/fork.c                  |    5 +--
 kernel/sched/auto_group.c      |    2 +-
 kernel/sched/auto_group.h      |    2 +-
 kernel/sched/core.c            |    4 +-
 kernel/sched/cputime.c         |    2 +-
 kernel/sched/deadline.c        |    2 +-
 kernel/sched/fair.c            |   26 +++++++++---
 kernel/sched/proc.c            |    4 +-
 kernel/sched/rt.c              |    2 +-
 kernel/sched/sched.h           |    2 +-
 kernel/sched/stats.h           |   15 ++-----
 kernel/sched/wait.c            |    4 +-
 kernel/time/posix-cpu-timers.c |   87 +++++++++++++++++++++++++---------------
 15 files changed, 113 insertions(+), 78 deletions(-)

-- 
1.7.2.5

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