From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH documentation 1/2] nohz1: Add documentation. Date: Thu, 11 Apr 2013 11:27:27 -0700 Message-ID: <20130411182727.GM29861@linux.vnet.ibm.com> References: <20130411160524.GA30384@linux.vnet.ibm.com> <1365696359-30958-1-git-send-email-paulmck@linux.vnet.ibm.com> <5166EF74.4030106@linux.intel.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, Borislav Petkov , Kevin Hilman , Christoph Lameter , arnd@arndb.de, Robin.Randhawa@arm.com, linux-rt-users@vger.kernel.org To: Arjan van de Ven Return-path: Received: from e31.co.us.ibm.com ([32.97.110.149]:42762 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751001Ab3DKS2B (ORCPT ); Thu, 11 Apr 2013 14:28:01 -0400 Received: from /spool/local by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 11 Apr 2013 12:27:59 -0600 Content-Disposition: inline In-Reply-To: <5166EF74.4030106@linux.intel.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Thu, Apr 11, 2013 at 10:14:28AM -0700, Arjan van de Ven wrote: > >+2. Many architectures will place dyntick-idle CPUs into deep sleep > >+ states, which further degrades from-idle transition latencies. > >+ > I think this part should just be deleted. > On x86, the deeper idle states are even used with non-tickless system (the break even times are > quite a bit less than even 1 msec). > I can't imagine that ARM is worse on this, at which point the statement above is highly dubious Interesting point, and I freely admit that I don't have full knowledge of the energy-consumption characteristics of all the architectures that Linux supports. Adding a few of the ARM guys on CC for their take, plus linux-rt-users. If there are no objections, I will delete point 2 above as Arjan suggests. Thanx, Paul