From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754627AbbBZXST (ORCPT ); Thu, 26 Feb 2015 18:18:19 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:51863 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754253AbbBZXSJ (ORCPT ); Thu, 26 Feb 2015 18:18:09 -0500 From: "Rafael J. Wysocki" To: Lorenzo Pieralisi Cc: Daniel Lezcano , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: [PATCH 1/2] idle / sleep: Avoid excessive interrupts disabling and enabling Date: Fri, 27 Feb 2015 00:39:21 +0100 Message-ID: <1903605.mzgLz6Rq43@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.19.0+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <4425438.YlYNQyf1hp@vostro.rjw.lan> References: <1424800730-32059-1-git-send-email-lorenzo.pieralisi@arm.com> <4425438.YlYNQyf1hp@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki Disabling interrupts at the end of cpuidle_enter_freeze() is not useful, because its caller, cpuidle_idle_call(), re-enables them right away after invoking it. To avoid that unnecessary back and forth dance with interrupts, make cpuidle_enter_freeze() enable interrupts after calling enter_freeze_proper() and drop the local_irq_disable() at its end, so that all of the code paths in it end up with interrupts enabled. Then, cpuidle_idle_call() will not need to re-enable interrupts after calling cpuidle_enter_freeze() any more, because the latter will return with interrupts enabled, in analogy with cpuidle_enter(). Reported-by: Lorenzo Pieralisi Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/cpuidle.c | 6 +++--- kernel/sched/idle.c | 1 - 2 files changed, 3 insertions(+), 4 deletions(-) Index: linux-pm/drivers/cpuidle/cpuidle.c =================================================================== --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -117,6 +117,8 @@ static void enter_freeze_proper(struct c * If there are states with the ->enter_freeze callback, find the deepest of * them and enter it with frozen tick. Otherwise, find the deepest state * available and enter it normally. + * + * Returns with enabled interrupts. */ void cpuidle_enter_freeze(void) { @@ -132,6 +134,7 @@ void cpuidle_enter_freeze(void) index = cpuidle_find_deepest_state(drv, dev, true); if (index >= 0) { enter_freeze_proper(drv, dev, index); + local_irq_enable(); return; } @@ -144,9 +147,6 @@ void cpuidle_enter_freeze(void) cpuidle_enter(drv, dev, index); else arch_cpu_idle(); - - /* Interrupts are enabled again here. */ - local_irq_disable(); } /** Index: linux-pm/kernel/sched/idle.c =================================================================== --- linux-pm.orig/kernel/sched/idle.c +++ linux-pm/kernel/sched/idle.c @@ -116,7 +116,6 @@ static void cpuidle_idle_call(void) */ if (idle_should_freeze()) { cpuidle_enter_freeze(); - local_irq_enable(); goto exit_idle; }