From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [RFC PATCH v3 1/9] CPU hotplug: Provide APIs to prevent CPU offline from atomic context Date: Tue, 11 Dec 2012 05:47:58 -0800 Message-ID: <20121211134758.GA7084@htj.dyndns.org> References: <20121207173702.27305.1486.stgit@srivatsabhat.in.ibm.com> <20121207173759.27305.84316.stgit@srivatsabhat.in.ibm.com> <20121209191437.GA2816@redhat.com> <50C4EB79.5050203@linux.vnet.ibm.com> <20121209202234.GA5793@redhat.com> <50C564ED.9090803@linux.vnet.ibm.com> <20121210172410.GA28479@redhat.com> <50C73192.9010905@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:45407 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752867Ab2LKNsG (ORCPT ); Tue, 11 Dec 2012 08:48:06 -0500 Content-Disposition: inline In-Reply-To: <50C73192.9010905@linux.vnet.ibm.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Srivatsa S. Bhat" Cc: Oleg Nesterov , tglx@linutronix.de, peterz@infradead.org, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, vincent.guittot@linaro.org, sbw@mit.edu, amit.kucheria@linaro.org, rostedt@goodmis.org, rjw@sisk.pl, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Hello, Srivatsa. On Tue, Dec 11, 2012 at 06:43:54PM +0530, Srivatsa S. Bhat wrote: > This approach (of using synchronize_sched()) also looks good. It is simple, > yet effective, but unfortunately inefficient at the writer side (because > he'll have to wait for a full synchronize_sched()). While synchornize_sched() is heavier on the writer side than the originally posted version, it doesn't stall the whole machine and wouldn't introduce latencies to others. Shouldn't that be enough? Thanks. -- tejun