All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Lameter <cl@linux.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
	laijs@cn.fujitsu.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
	peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com,
	edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com,
	sbw@mit.edu
Subject: Re: [PATCH RFC nohz_full 0/7] v2 Provide infrastructure for full-system idle
Date: Mon, 1 Jul 2013 19:43:47 +0000	[thread overview]
Message-ID: <0000013f9bc32a5e-258db1be-840b-4b2f-9b3f-e1e3d5253cfc-000000@email.amazonses.com> (raw)
In-Reply-To: <20130628200949.GA17458@linux.vnet.ibm.com>

On Fri, 28 Jun 2013, Paul E. McKenney wrote:

> Unfortunately, timekeeping CPU continues taking scheduling-clock
> interrupts even when all other CPUs are completely idle, which is
> not so good for energy efficiency and battery lifetime.  Clearly, it
> would be good to turn off the timekeeping CPU's scheduling-clock tick
> when all CPUs are completely idle.  This is conceptually simple, but
> we also need good performance and scalability on large systems, which
> rules out implementations based on frequently updated global counts of
> non-idle CPUs as well as implementations that frequently scan all CPUs.
> Nevertheless, we need a single global indicator in order to keep the
> overhead of checking acceptably low.

Can we turn off timekeeping when no cpu needs time in adaptive mode?
Setting breakpoints in the VDSO could force timekeeping on again whenever
something needs time. Would this not be simpler?

  parent reply	other threads:[~2013-07-01 19:43 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-28 20:09 [PATCH RFC nohz_full 0/7] v2 Provide infrastructure for full-system idle Paul E. McKenney
2013-06-28 20:10 ` [PATCH RFC nohz_full v2 1/7] nohz_full: Add Kconfig parameter for scalable detection of all-idle state Paul E. McKenney
2013-06-28 20:10   ` [PATCH RFC nohz_full v2 2/7] nohz_full: Add rcu_dyntick data " Paul E. McKenney
2013-07-01 15:31     ` Josh Triplett
2013-07-01 15:52       ` Paul E. McKenney
2013-07-01 18:16         ` Josh Triplett
2013-07-01 18:23           ` Paul E. McKenney
2013-07-01 18:34             ` Josh Triplett
2013-07-01 19:16               ` Paul E. McKenney
2013-07-02  5:10                 ` Mike Galbraith
2013-07-02  5:58                   ` Paul E. McKenney
2013-06-28 20:10   ` [PATCH RFC nohz_full v2 3/7] nohz_full: Add per-CPU idle-state tracking Paul E. McKenney
2013-07-01 15:33     ` Josh Triplett
2013-06-28 20:10   ` [PATCH RFC nohz_full v2 4/7] nohz_full: Add full-system idle states and variables Paul E. McKenney
2013-06-28 20:10   ` [PATCH RFC nohz_full v2 5/7] nohz_full: Add full-system-idle arguments to API Paul E. McKenney
2013-06-28 20:10   ` [PATCH RFC nohz_full v2 6/7] nohz_full: Add full-system-idle state machine Paul E. McKenney
2013-07-01 16:35     ` Frederic Weisbecker
2013-07-01 18:10       ` Paul E. McKenney
2013-07-01 20:55         ` Frederic Weisbecker
2013-07-01 16:53     ` Frederic Weisbecker
2013-07-01 18:17       ` Paul E. McKenney
2013-07-01 21:38     ` Frederic Weisbecker
2013-07-01 22:51       ` Paul E. McKenney
2013-06-28 20:10   ` [PATCH RFC nohz_full v2 7/7] nohz_full: Force RCU's grace-period kthreads onto timekeeping CPU Paul E. McKenney
2013-07-01 15:19 ` [PATCH RFC nohz_full 0/7] v2 Provide infrastructure for full-system idle Andi Kleen
2013-07-01 16:03   ` Paul E. McKenney
2013-07-01 16:19     ` Andi Kleen
2013-07-01 19:19       ` Paul E. McKenney
2013-07-01 19:43 ` Christoph Lameter [this message]
2013-07-01 19:56   ` Paul E. McKenney
2013-07-01 20:24     ` Christoph Lameter
2013-07-01 20:43       ` Thomas Gleixner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=0000013f9bc32a5e-258db1be-840b-4b2f-9b3f-e1e3d5253cfc-000000@email.amazonses.com \
    --to=cl@linux.com \
    --cc=akpm@linux-foundation.org \
    --cc=darren@dvhart.com \
    --cc=dhowells@redhat.com \
    --cc=dipankar@in.ibm.com \
    --cc=edumazet@google.com \
    --cc=fweisbec@gmail.com \
    --cc=josh@joshtriplett.org \
    --cc=laijs@cn.fujitsu.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mingo@elte.hu \
    --cc=niv@us.ibm.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=sbw@mit.edu \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.