From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qa0-x22f.google.com (mail-qa0-x22f.google.com [IPv6:2607:f8b0:400d:c00::22f]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 1814D2C0098 for ; Thu, 27 Jun 2013 07:35:09 +1000 (EST) Received: by mail-qa0-f47.google.com with SMTP id i13so1973206qae.6 for ; Wed, 26 Jun 2013 14:35:05 -0700 (PDT) Sender: Tejun Heo Date: Wed, 26 Jun 2013 14:34:58 -0700 From: Tejun Heo To: "Srivatsa S. Bhat" Subject: Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline Message-ID: <20130626213458.GC4536@htj.dyndns.org> References: <20130625202755.16593.67819.stgit@srivatsabhat.in.ibm.com> <20130625220026.GG3828@linux.vnet.ibm.com> <51CAF624.6060004@linux.vnet.ibm.com> <20130626143424.GN3828@linux.vnet.ibm.com> <1372258271.18733.256.camel@gandalf.local.home> <20130626152148.GA4405@mtj.dyndns.org> <1372260823.18733.263.camel@gandalf.local.home> <20130626172948.GD4405@mtj.dyndns.org> <51CB32E0.3040106@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <51CB32E0.3040106@linux.vnet.ibm.com> Cc: peterz@infradead.org, fweisbec@gmail.com, linux-kernel@vger.kernel.org, walken@google.com, mingo@kernel.org, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, xiaoguangrong@linux.vnet.ibm.com, wangyun@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, rusty@rustcorp.com.au, Steven Rostedt , namhyung@kernel.org, tglx@linutronix.de, laijs@cn.fujitsu.com, zhong@linux.vnet.ibm.com, netdev@vger.kernel.org, oleg@redhat.com, sbw@mit.edu, David Laight , akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hey, On Wed, Jun 26, 2013 at 11:58:48PM +0530, Srivatsa S. Bhat wrote: > Yes, we were discussing hot-unplug latency for use-cases such as > suspend/resume. We didn't want to make those operations slower in the > process of removing stop_machine() from hotplug. Can you please explain why tho? How much would it help in terms of power-saving? Or are there other issues in taking longer to shut down cpus? Thanks. -- tejun