Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759171Ab1FWJ0R (ORCPT ); Thu, 23 Jun 2011 05:26:17 -0400 Received: from casper.infradead.org ([85.118.1.10]:53311 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759153Ab1FWJ0N convert rfc822-to-8bit (ORCPT ); Thu, 23 Jun 2011 05:26:13 -0400 Subject: Re: [patch 3/4] stop_machine: implement stop_machine_from_offline_cpu() From: Peter Zijlstra To: Suresh Siddha Cc: mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, trenn@novell.com, prarit@redhat.com, tj@kernel.org, rusty@rustcorp.com.au, akpm@linux-foundation.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, youquan.song@intel.com In-Reply-To: <20110622222044.038298780@sbsiddha-MOBL3.sc.intel.com> References: <20110622222021.904952469@sbsiddha-MOBL3.sc.intel.com> <20110622222044.038298780@sbsiddha-MOBL3.sc.intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 23 Jun 2011 11:25:19 +0200 Message-ID: <1308821119.1022.84.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1878 Lines: 43 On Wed, 2011-06-22 at 15:20 -0700, Suresh Siddha wrote: > +int stop_machine_from_offline_cpu(int (*fn)(void *), void *data, > + const struct cpumask *cpus) > +{ > + struct stop_machine_data smdata = { .fn = fn, .data = data, > + .active_cpus = cpus }; > + struct cpu_stop_done done; > + int ret; > + > + /* Local CPU must be offline and CPU hotplug in progress. */ > + BUG_ON(cpu_online(raw_smp_processor_id())); > + smdata.num_threads = num_online_cpus() + 1; /* +1 for local */ > + > + /* No proper task established and can't sleep - busy wait for lock. */ > + while (!mutex_trylock(&stop_cpus_mutex)) > + cpu_relax(); > + > + /* Schedule work on other CPUs and execute directly for local CPU */ > + set_state(&smdata, STOPMACHINE_PREPARE); > + cpu_stop_init_done(&done, num_online_cpus()); > + queue_stop_cpus_work(cpu_online_mask, stop_machine_cpu_stop, &smdata, > + &done); > + ret = stop_machine_cpu_stop(&smdata); > + > + /* Busy wait for completion. */ > + while (!completion_done(&done.completion)) > + cpu_relax(); > + > + mutex_unlock(&stop_cpus_mutex); > + return ret ?: done.ret; > +} Damn thats ugly, I sure hope you're going to make those hardware folks pay for this :-) In commit d0af9eed5aa91b6b7b5049cae69e5ea956fd85c3 you mention that its specific to HT, wouldn't it make sense to limit the stop-machine use in the next patch to the sibling mask instead of the whole machine? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/