From patchwork Sun Feb 10 08:10:28 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Len Brown X-Patchwork-Id: 2121711 X-Patchwork-Delegate: lenb@kernel.org Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id 720C2E014A for ; Sun, 10 Feb 2013 08:10:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752742Ab3BJIKq (ORCPT ); Sun, 10 Feb 2013 03:10:46 -0500 Received: from mail-vb0-f52.google.com ([209.85.212.52]:39472 "EHLO mail-vb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267Ab3BJIKl (ORCPT ); Sun, 10 Feb 2013 03:10:41 -0500 Received: by mail-vb0-f52.google.com with SMTP id fa15so3219180vbb.11 for ; Sun, 10 Feb 2013 00:10:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:from:to:cc:subject:date:message-id:x-mailer :in-reply-to:references:reply-to:organization; bh=anuHP3PVcv28Z0b8jSilO0XvXGG22vaXusDhmx3JuMI=; b=WB3/gYftade/WxhEC0OH0a0jF0auDesR8pTeYFvdLYwTJ5okPiCNCF2j2GUQYohuvR tFBcYmYXkoUn74w5hdNPBaFVg/XHUYNi484wPg2VbhfhFESZRxMooNhzzJik4SYISIhT uThTKLegw756rHT2i352py8SyJVDfmwn889WeZRrGrAtF9IRUheScobME6veynCJUP5g NDdQjAnW7pthYVM54Nn0gZQxhe2g2/WQo3XmUNCKBr005u5x9TXYsYA4EXT+gf18mINh wrOG18giPN/SL+a9CRun7TmjipYnMWZtEsHrMC0ZWvtg4ieC+P7ftouByLPUXwHbIXfj y9SQ== X-Received: by 10.58.106.161 with SMTP id gv1mr14015626veb.35.1360483839367; Sun, 10 Feb 2013 00:10:39 -0800 (PST) Received: from x980.localdomain6 (pool-108-7-58-246.bstnma.fios.verizon.net. [108.7.58.246]) by mx.google.com with ESMTPS id e8sm12357371vdt.7.2013.02.10.00.10.38 (version=TLSv1 cipher=RC4-SHA bits=128/128); Sun, 10 Feb 2013 00:10:38 -0800 (PST) From: Len Brown To: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Len Brown , x86@kernel.org Subject: [PATCH 1/2] x86 idle: remove mwait_idle() and "idle=mwait" cmdline param Date: Sun, 10 Feb 2013 03:10:28 -0500 Message-Id: <69fb3676df3329a7142803bb3502fa59dc0db2e3.1360483568.git.len.brown@intel.com> X-Mailer: git-send-email 1.8.1.3.535.ga923c31 In-Reply-To: <1360483829-16349-1-git-send-email-lenb@kernel.org> References: <1360483829-16349-1-git-send-email-lenb@kernel.org> Reply-To: Len Brown Organization: Intel Open Source Technology Center Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Len Brown mwait_idle() is a C1-only idle loop intended to be more efficient than HLT, starting on Pentium-4 HT-enabled processors. But mwait_idle() has been replaced by the more general mwait_idle_with_hints(), which handles both C1 and deeper C-states. ACPI processor_idle and intel_idle use only mwait_idle_with_hints(), and no longer use mwait_idle(). Here we simplify the x86 native idle code by removing mwait_idle(), and the "idle=mwait" bootparam used to invoke it. Since Linux 3.0 there has been a boot-time warning when "idle=mwait" was invoked saying it would be removed in 2012. This removal was also noted in the (now removed:-) feature-removal-schedule.txt. After this change, kernels configured with (CONFIG_ACPI=n && CONFIG_INTEL_IDLE=n) when run on hardware that supports MWAIT will simply use HLT. If MWAIT is desired on those systems, cpuidle and the cpuidle drivers above can be enabled. Signed-off-by: Len Brown Cc: x86@kernel.org --- Documentation/kernel-parameters.txt | 7 +--- arch/x86/include/asm/processor.h | 2 +- arch/x86/kernel/process.c | 79 +------------------------------------ arch/x86/kernel/smpboot.c | 2 +- drivers/acpi/processor_idle.c | 1 - 5 files changed, 4 insertions(+), 87 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 363e348..3b0cd1e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1039,16 +1039,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Claim all unknown PCI IDE storage controllers. idle= [X86] - Format: idle=poll, idle=mwait, idle=halt, idle=nomwait + Format: idle=poll, idle=halt, idle=nomwait Poll forces a polling idle loop that can slightly improve the performance of waking up a idle CPU, but will use a lot of power and make the system run hot. Not recommended. - idle=mwait: On systems which support MONITOR/MWAIT but - the kernel chose to not use it because it doesn't save - as much power as a normal idle loop, use the - MONITOR/MWAIT idle loop anyways. Performance should be - the same as idle=poll. idle=halt: Halt is forced to be used for CPU idle. In such case C2/C3 won't be used again. idle=nomwait: Disable mwait for CPU C-states diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index c2f7f47..8a28fea 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -725,7 +725,7 @@ extern unsigned long boot_option_idle_override; extern bool amd_e400_c1e_detected; enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT, - IDLE_POLL, IDLE_FORCE_MWAIT}; + IDLE_POLL}; extern void enable_sep_cpu(void); extern int sysenter_setup(void); diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 7ed9f6b0..cd5a4c9 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -421,27 +421,6 @@ void stop_this_cpu(void *dummy) } } -/* Default MONITOR/MWAIT with no hints, used for default C1 state */ -static void mwait_idle(void) -{ - if (!need_resched()) { - trace_power_start_rcuidle(POWER_CSTATE, 1, smp_processor_id()); - trace_cpu_idle_rcuidle(1, smp_processor_id()); - if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) - clflush((void *)¤t_thread_info()->flags); - - __monitor((void *)¤t_thread_info()->flags, 0, 0); - smp_mb(); - if (!need_resched()) - __sti_mwait(0, 0); - else - local_irq_enable(); - trace_power_end_rcuidle(smp_processor_id()); - trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); - } else - local_irq_enable(); -} - /* * On SMP it's slightly faster (but much more power-consuming!) * to poll the ->work.need_resched flag instead of waiting for the @@ -458,53 +437,6 @@ static void poll_idle(void) trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); } -/* - * mwait selection logic: - * - * It depends on the CPU. For AMD CPUs that support MWAIT this is - * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings - * then depend on a clock divisor and current Pstate of the core. If - * all cores of a processor are in halt state (C1) the processor can - * enter the C1E (C1 enhanced) state. If mwait is used this will never - * happen. - * - * idle=mwait overrides this decision and forces the usage of mwait. - */ - -#define MWAIT_INFO 0x05 -#define MWAIT_ECX_EXTENDED_INFO 0x01 -#define MWAIT_EDX_C1 0xf0 - -int mwait_usable(const struct cpuinfo_x86 *c) -{ - u32 eax, ebx, ecx, edx; - - /* Use mwait if idle=mwait boot option is given */ - if (boot_option_idle_override == IDLE_FORCE_MWAIT) - return 1; - - /* - * Any idle= boot option other than idle=mwait means that we must not - * use mwait. Eg: idle=halt or idle=poll or idle=nomwait - */ - if (boot_option_idle_override != IDLE_NO_OVERRIDE) - return 0; - - if (c->cpuid_level < MWAIT_INFO) - return 0; - - cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx); - /* Check, whether EDX has extended info about MWAIT */ - if (!(ecx & MWAIT_ECX_EXTENDED_INFO)) - return 1; - - /* - * edx enumeratios MONITOR/MWAIT extensions. Check, whether - * C1 supports MWAIT - */ - return (edx & MWAIT_EDX_C1); -} - bool amd_e400_c1e_detected; EXPORT_SYMBOL(amd_e400_c1e_detected); @@ -576,13 +508,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) if (pm_idle) return; - if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) { - /* - * One CPU supports mwait => All CPUs supports mwait - */ - pr_info("using mwait in idle threads\n"); - pm_idle = mwait_idle; - } else if (cpu_has_amd_erratum(amd_erratum_400)) { + if (cpu_has_amd_erratum(amd_erratum_400)) { /* E400: APIC timer interrupt does not wake up CPU from C1e */ pr_info("using AMD E400 aware idle routine\n"); pm_idle = amd_e400_idle; @@ -606,9 +532,6 @@ static int __init idle_setup(char *str) pr_info("using polling idle threads\n"); pm_idle = poll_idle; boot_option_idle_override = IDLE_POLL; - } else if (!strcmp(str, "mwait")) { - boot_option_idle_override = IDLE_FORCE_MWAIT; - WARN_ONCE(1, "\"idle=mwait\" will be removed in 2012\n"); } else if (!strcmp(str, "halt")) { /* * When the boot option of idle=halt is added, halt is diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index ed0fe38..a6ceaed 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1369,7 +1369,7 @@ static inline void mwait_play_dead(void) void *mwait_ptr; struct cpuinfo_x86 *c = __this_cpu_ptr(&cpu_info); - if (!(this_cpu_has(X86_FEATURE_MWAIT) && mwait_usable(c))) + if (!this_cpu_has(X86_FEATURE_MWAIT)) return; if (!this_cpu_has(X86_FEATURE_CLFLSH)) return; diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index ed9a1cc..52a5e3a 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -84,7 +84,6 @@ static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device); static int disabled_by_idle_boot_param(void) { return boot_option_idle_override == IDLE_POLL || - boot_option_idle_override == IDLE_FORCE_MWAIT || boot_option_idle_override == IDLE_HALT; }