linux-kernel - Re: [GIT PULL timers] Timer-wheel bandaids^Wcommits

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Message-ID: <20140130084835.GC9012@linux.vnet.ibm.com>
Date:	Thu, 30 Jan 2014 00:48:35 -0800
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Preeti Murthy <preeti.lkml@...il.com>
Cc:	mingo@...nel.org, josh@...htriplett.org,
	Peter Zijlstra <peterz@...radead.org>, oleg@...hat.com,
	rostedt@...dmis.org, bitbucket@...ine.de,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Subject: Re: [GIT PULL timers] Timer-wheel bandaids^Wcommits

On Thu, Jan 30, 2014 at 11:14:57AM +0530, Preeti Murthy wrote:
> Hi Paul,
> 
> The commit id:e1d690cdc07637131ba4334: timers: Track total number of
> timers in list has
> a minor glitch in the changelog.
> 
> I am referring to your
> git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
> rcu/timers branch.
> 
> "even if ->active_timers is zero, there might well be *non-deferrable*
> timers in the list"
> 
> s/non-deferrable/deferrable.

Good catch, fixed!  New pull request below, very similar to the last one.

							Thanx, Paul
------------------------------------------------------------------------

Hello, Ingo,

This pull request contains latency bandaids^Woptimizations to the
timer-wheel code that are useful in conjunction with NO_HZ_FULL Kconfig
option.  These optimizations reduce the jiffy-by-jiffy looping in cases
where there is either zero or one timers in the timer wheel, which is
a common case for NO_HZ_FULL "worker" CPUs that run almost entirely
in usermode for a single task.

Each of these commits has at least two Reviewed-by, one Acked-by, and
one Tested-by tag, so they are ready for more extensive testing in -tip.

                                                        Thanx, Paul

The following changes since commit 00e2bcd6d35f59fce7fa0e76e24d08f74c6a8506:

  clocksource: Timer-sun5i: Switch to sched_clock_register() (2014-01-19 13:23:23 +0100)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/timers

for you to fetch changes up to 73bffac4cf615295055df086e95d0284754aa708

  timers: Make internal_add_timer() update ->next_timer if ->active_timers == 0 (2014-01-30 00:41:53 -0800)

----------------------------------------------------------------
Oleg Nesterov (1):
      timers: Make internal_add_timer() update ->next_timer if ->active_timers == 0

Paul E. McKenney (4):
      timers: Track total number of timers in list
      timers: Reduce __run_timers() latency for empty list
      timers: Reduce future __run_timers() latency for newly emptied list
      timers: Reduce future __run_timers() latency for first add to empty list

 kernel/timer.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

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