From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
pjt@google.com, paul.mckenney@linaro.org, tglx@linutronix.de,
tj@kernel.org, suresh.b.siddha@intel.com, venki@google.com,
mingo@redhat.com, peterz@infradead.org, Arvind.Chauhan@arm.com,
linaro-dev@lists.linaro.org, patches@linaro.org,
pdsw-power-team@arm.com, linux-kernel@vger.kernel.org,
linux-rt-users@vger.kernel.org
Subject: Re: [PATCH V2 Resend 0/4] Create sched_select_cpu() and use it for workqueues and timers
Date: Mon, 26 Nov 2012 11:03:54 -0800 [thread overview]
Message-ID: <20121126190354.GJ2474@linux.vnet.ibm.com> (raw)
In-Reply-To: <1353951352.6276.43.camel@gandalf.local.home>
On Mon, Nov 26, 2012 at 12:35:52PM -0500, Steven Rostedt wrote:
> On Mon, 2012-11-26 at 09:03 -0800, Paul E. McKenney wrote:
>
>
> > If I understand correctly (though also suffering turkey OD), the idea is
> > to offload work to more energy-efficient CPUs.
>
> This is determined by a CPU that isn't running the idle task? Is it
> because a CPU that just woke up may be running at a lower freq, and thus
> not as efficient? But pushing off to another CPU may cause cache misses
> as well. Wouldn't that also be a factor in efficiencies, if a CPU is
> stalled waiting for memory to be loaded?
Two different microarchitectures -- same instruction set (at user level,
anyway), but different power/performance characteristics. One set is
optimized for performance, the other for energy efficiency. For example,
ARM's big.LITTLE architecture.
> I should also ask the obvious. Has these patches shown real world
> efficiencies or is this just a theory? Do these patches actually improve
> battery life when applied?
I must defer to Viresh on this one.
Thanx, Paul
> Just asking.
>
> -- Steve
>
>
next prev parent reply other threads:[~2012-11-26 19:04 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-06 10:34 [PATCH V2 Resend 0/4] Create sched_select_cpu() and use it for workqueues and timers Viresh Kumar
2012-11-06 10:38 ` [PATCH V2 Resend 1/4] sched: Create sched_select_cpu() to give preferred CPU for power saving Viresh Kumar
2012-11-06 10:38 ` [PATCH V2 Resend 2/4] timer: hrtimer: Don't check idle_cpu() before calling get_nohz_timer_target() Viresh Kumar
2012-11-06 10:38 ` [PATCH V2 Resend 3/4] workqueue: Schedule work on non-idle cpu instead of current one Viresh Kumar
2012-11-26 17:15 ` Tejun Heo
2012-11-27 5:19 ` Viresh Kumar
2012-11-27 12:54 ` Vincent Guittot
2013-01-04 11:11 ` Viresh Kumar
2013-01-04 15:09 ` Tejun Heo
2013-01-07 9:58 ` Viresh Kumar
2013-01-07 13:28 ` Steven Rostedt
2013-01-07 17:59 ` Viresh Kumar
2013-01-07 22:29 ` Steven Rostedt
2013-01-08 4:03 ` Viresh Kumar
2013-01-07 15:04 ` Tejun Heo
2013-01-07 15:40 ` Amit Kucheria
2013-01-07 18:07 ` Viresh Kumar
2013-01-09 18:49 ` Tejun Heo
2013-01-10 5:04 ` Viresh Kumar
2012-11-27 13:26 ` Steven Rostedt
2012-11-27 13:48 ` Viresh Kumar
2012-11-27 13:59 ` Steven Rostedt
2012-11-27 14:55 ` Vincent Guittot
2012-11-27 15:04 ` Steven Rostedt
2012-11-27 15:35 ` Vincent Guittot
2012-11-06 10:38 ` [PATCH V2 Resend 4/4] timer: Migrate running timer Viresh Kumar
2012-11-27 13:47 ` Steven Rostedt
2013-03-20 15:13 ` Viresh Kumar
2013-04-09 14:52 ` Viresh Kumar
2013-04-24 11:22 ` Viresh Kumar
2013-05-13 9:19 ` Viresh Kumar
2013-05-13 10:35 ` Thomas Gleixner
2013-05-22 8:34 ` Viresh Kumar
2013-05-22 9:06 ` Peter Zijlstra
2013-05-22 9:23 ` Viresh Kumar
2013-05-31 10:49 ` Viresh Kumar
2013-06-18 4:51 ` Viresh Kumar
2013-07-24 9:17 ` Viresh Kumar
2013-08-07 9:55 ` Viresh Kumar
2013-10-04 12:39 ` Sebastian Andrzej Siewior
2013-10-23 5:55 ` Viresh Kumar
2012-11-26 15:00 ` [PATCH V2 Resend 0/4] Create sched_select_cpu() and use it for workqueues and timers Viresh Kumar
2012-11-26 16:40 ` Steven Rostedt
2012-11-26 17:03 ` Paul E. McKenney
2012-11-26 17:35 ` Steven Rostedt
2012-11-26 19:03 ` Paul E. McKenney [this message]
2012-11-26 19:17 ` Steven Rostedt
2012-11-27 6:25 ` Viresh Kumar
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