From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline Date: Wed, 26 Jun 2013 08:21:48 -0700 Message-ID: <20130626152148.GA4405@mtj.dyndns.org> References: <20130625202452.16593.22810.stgit@srivatsabhat.in.ibm.com> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: paulmck@linux.vnet.ibm.com, David Laight , "Srivatsa S. Bhat" , 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, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, rusty@rustcorp.com.au, 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, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org To: Steven Rostedt Return-path: Content-Disposition: inline In-Reply-To: <1372258271.18733.256.camel@gandalf.local.home> Sender: linux-arch-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Jun 26, 2013 at 10:51:11AM -0400, Steven Rostedt wrote: > > It would also increase the latency of CPU-hotunplug operations. > > Is that a big deal? I thought that was the whole deal with this patchset - making cpu hotunplugs lighter and faster mostly for powersaving. That said, just removing stop_machine call would be a pretty good deal and I don't know how meaningful reducing CPU hotunplug latency is. Srivatsa? Thanks. -- tejun