From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751959AbaHDJBl (ORCPT ); Mon, 4 Aug 2014 05:01:41 -0400 Received: from mga14.intel.com ([192.55.52.115]:39415 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751551AbaHDJBk (ORCPT ); Mon, 4 Aug 2014 05:01:40 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="367559750" From: Lan Tianyu To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, toshi.kani@hp.com, imammedo@redhat.com, bp@alien8.de, jan.kiszka@siemens.com, tianyu.lan@intel.com Cc: mingo@kernel.org, huawei.libin@huawei.com, prarit@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH] X86/CPU: Avoid 100ms sleep for cpu offline during S3 Date: Mon, 4 Aug 2014 16:59:02 +0800 Message-Id: <1407142742-29202-1-git-send-email-tianyu.lan@intel.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some test result shows cpu offline consumes more than 100ms during S3. After some researchs, found native_cpu_die() would fall into 100ms sleep if cpu idle loop thread marked cpu state slower. What native_cpu_die() does is that poll cpu state and wait for 100ms if cpu state hasn't been marked to DEAD. The 100ms sleep doesn't make sense. To avoid such long sleep, this patch is to add struct completion to each cpu, wait for the completion in the native_cpu_die() and wakeup the completion when the cpu state is marked to DEAD. Signed-off-by: Lan Tianyu --- arch/x86/kernel/smpboot.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 5492798..15d9d9f 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -102,6 +102,9 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map); DEFINE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info); EXPORT_PER_CPU_SYMBOL(cpu_info); +DEFINE_PER_CPU(struct completion, die_complete); + + atomic_t init_deasserted; /* @@ -1331,7 +1334,7 @@ int native_cpu_disable(void) return ret; clear_local_APIC(); - + init_completion(&per_cpu(die_complete, smp_processor_id())); cpu_disable_common(); return 0; } @@ -1339,18 +1342,16 @@ int native_cpu_disable(void) void native_cpu_die(unsigned int cpu) { /* We don't do anything here: idle task is faking death itself. */ - unsigned int i; + wait_for_completion_timeout(&per_cpu(die_complete, cpu), + msecs_to_jiffies(1000)); - for (i = 0; i < 10; i++) { - /* They ack this in play_dead by setting CPU_DEAD */ - if (per_cpu(cpu_state, cpu) == CPU_DEAD) { - if (system_state == SYSTEM_RUNNING) - pr_info("CPU %u is now offline\n", cpu); - return; - } - msleep(100); - } - pr_err("CPU %u didn't die...\n", cpu); + /* They ack this in play_dead by setting CPU_DEAD */ + if (per_cpu(cpu_state, cpu) == CPU_DEAD) { + if (system_state == SYSTEM_RUNNING) + pr_info("CPU %u is now offline\n", cpu); + return; + } else + pr_err("CPU %u didn't die...\n", cpu); } void play_dead_common(void) @@ -1362,6 +1363,7 @@ void play_dead_common(void) mb(); /* Ack it */ __this_cpu_write(cpu_state, CPU_DEAD); + complete(&per_cpu(die_complete, smp_processor_id())); /* * With physical CPU hotplug, we should halt the cpu -- 1.8.4.rc0.1.g8f6a3e5.dirty