From patchwork Fri Feb 12 20:50:31 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lina Iyer X-Patchwork-Id: 8297311 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 3FC779F1C5 for ; Fri, 12 Feb 2016 20:51:32 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 622732042C for ; Fri, 12 Feb 2016 20:51:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8294120444 for ; Fri, 12 Feb 2016 20:51:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751101AbcBLUv2 (ORCPT ); Fri, 12 Feb 2016 15:51:28 -0500 Received: from mail-pf0-f172.google.com ([209.85.192.172]:32937 "EHLO mail-pf0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046AbcBLUv1 (ORCPT ); Fri, 12 Feb 2016 15:51:27 -0500 Received: by mail-pf0-f172.google.com with SMTP id q63so52948758pfb.0 for ; Fri, 12 Feb 2016 12:51:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=JdwV59Mr9zc6V6lqdT4XAPyzCzJVVJRH3T1LlDKeRG4=; b=CULj1mQGg+0WaRt2j5FZYH+jc1I0VJYpb/i4FDRFpd8TAV8krpG3/USy9UHesPizw0 QNJYHLLdFktGvqWFB2VMYI9Eyq5D4/aYeE1GV28No4bexaTfgiq3Xno4c1Tlq/HtcOw4 ne3GdGtvHXNvef+LTdk82oYkDnFvrNh9V9WDA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=JdwV59Mr9zc6V6lqdT4XAPyzCzJVVJRH3T1LlDKeRG4=; b=mmgSLe3Ke7Ob0Ckmh9qVcbUmsaSO3qJUyfA1EY9BNFxlKGpMdzK/4El2q2BVx8ohnW EY83xtWc1hUR0Cjtb7Nk8IZ2fnGvMtLdG1yvfPq4H8XqSLlea3u/sza71VFJDGsLvZfI M8JUplyGcBNgypIB9G6Tadq72AYIPN713ecAJjJz6KPDHFJhLexTL4H61zdAEjCXHRN7 ZLYd+up/ulDrRwbz67ULQulwlr3zLyBC1brGrTJBKM0T+pYyuju3ZT4rJqyhTuPprlw0 C1ESzBUyMGItQohBXHVDfMnNZsHVzL+7d3WeqE0rM20kNKIu2zN8chJ/6s359/60duVO 8vGw== X-Gm-Message-State: AG10YOQn0yoaFJUBN+rM4IQqGBBRvTFdnnyLhVXSmikg3aC7k/HrynVTAC7XVOXVdrLjoFNO X-Received: by 10.98.74.144 with SMTP id c16mr5056330pfj.129.1455310287293; Fri, 12 Feb 2016 12:51:27 -0800 (PST) Received: from ubuntu.localdomain ([172.56.8.98]) by smtp.gmail.com with ESMTPSA id x12sm21401070pfi.88.2016.02.12.12.51.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 12 Feb 2016 12:51:26 -0800 (PST) From: Lina Iyer To: ulf.hansson@linaro.org, khilman@kernel.org, rjw@rjwysocki.net, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: geert@linux-m68k.org, k.kozlowski@samsung.com, msivasub@codeaurora.org, agross@codeaurora.org, sboyd@codeaurora.org, linux-arm-msm@vger.kernel.org, lorenzo.pieralisi@arm.com, ahaslam@baylibre.com, mtitinger@baylibre.com, Lina Iyer , Thomas Gleixner Subject: [RFC v2 05/12] timer: Export next wake up of a CPU Date: Fri, 12 Feb 2016 13:50:31 -0700 Message-Id: <1455310238-8963-6-git-send-email-lina.iyer@linaro.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1455310238-8963-1-git-send-email-lina.iyer@linaro.org> References: <1455310238-8963-1-git-send-email-lina.iyer@linaro.org> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Knowing the sleep length of the CPU is useful for the power state determination on idle. However, when the common sleep time between multiple CPUs is needed, the sleep length of a CPU is not useful. By reading the next wake up event of a CPU, governors can determine the first CPU to wake up (due to timer) amongst a cluster of CPUs and the sleep time available between the last CPU to idle and the first CPU to resume. This information is useful to determine if the caches and other common hardware blocks can also be put in idle during this common period of inactivity. Cc: Thomas Gleixner Signed-off-by: Lina Iyer --- Changes since RFC v1 - - any CPU can access this variable if that CPU has IRQs disabled include/linux/tick.h | 10 ++++++++++ kernel/time/tick-sched.c | 13 +++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 97fd4e5..b8a2e06 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -104,6 +104,7 @@ extern void tick_nohz_idle_enter(void); extern void tick_nohz_idle_exit(void); extern void tick_nohz_irq_exit(void); extern ktime_t tick_nohz_get_sleep_length(void); +extern ktime_t tick_nohz_get_next_wakeup(int cpu); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); #else /* !CONFIG_NO_HZ_COMMON */ @@ -118,6 +119,15 @@ static inline ktime_t tick_nohz_get_sleep_length(void) return len; } + +static inline ktime_t tick_nohz_get_next_wakeup(int cpu) +{ + ktime_t len = { .tv64 = NSEC_PER_SEC/HZ }; + + /* Next wake up is the tick period, assume it starts now */ + return ktime_add(len, ktime_get()); +} + static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; } #endif /* !CONFIG_NO_HZ_COMMON */ diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 0b17424..f0ddaec 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -888,6 +888,19 @@ ktime_t tick_nohz_get_sleep_length(void) return ts->sleep_length; } +/** + * tick_nohz_get_next_wakeup - return the next wake up of the CPU + * + * Called with interrupts disabled on the cpu + */ +ktime_t tick_nohz_get_next_wakeup(int cpu) +{ + struct clock_event_device *dev = + per_cpu(tick_cpu_device.evtdev, cpu); + + return dev->next_event; +} + static void tick_nohz_account_idle_ticks(struct tick_sched *ts) { #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE