From patchwork Mon Mar 12 10:05:59 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. Wysocki" X-Patchwork-Id: 10275903 X-Patchwork-Delegate: rjw@sisk.pl Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BEC27601A0 for ; Mon, 12 Mar 2018 10:10:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BC1B128CE8 for ; Mon, 12 Mar 2018 10:10:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B0CD428CEC; Mon, 12 Mar 2018 10:10:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 352D928CE8 for ; Mon, 12 Mar 2018 10:10:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932188AbeCLKHf (ORCPT ); Mon, 12 Mar 2018 06:07:35 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:60497 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751263AbeCLKHe (ORCPT ); Mon, 12 Mar 2018 06:07:34 -0400 Received: from 79.184.254.228.ipv4.supernova.orange.pl (79.184.254.228) (HELO aspire.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83) id e942b98a735eff91; Mon, 12 Mar 2018 11:07:32 +0100 From: "Rafael J. Wysocki" To: Peter Zijlstra , Linux PM , Frederic Weisbecker Cc: Thomas Gleixner , Paul McKenney , Thomas Ilsche , Doug Smythies , Rik van Riel , Aubrey Li , Mike Galbraith , LKML Subject: [RFT][PATCH v4 6/7] cpuidle: menu: Refine idle state selection for running tick Date: Mon, 12 Mar 2018 11:05:59 +0100 Message-ID: <7247268.klz2FnhlQ9@aspire.rjw.lan> In-Reply-To: <2352117.3UUoYAu18A@aspire.rjw.lan> References: <2352117.3UUoYAu18A@aspire.rjw.lan> MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Rafael J. Wysocki If the tick isn't stopped, the target residency of the state selected by the menu governor may be greater than the actual time to the next tick and that means lost energy. To avoid that, make tick_nohz_get_sleep_length() return the current time the the next event (before stopping the tick) in addition to the estimated one via an extra pointer argument and make menu_select() use that value to refine the state selection when necessary. Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/governors/menu.c | 21 ++++++++++++++++++--- include/linux/tick.h | 2 +- kernel/time/tick-sched.c | 7 +++++-- 3 files changed, 24 insertions(+), 6 deletions(-) Index: linux-pm/include/linux/tick.h =================================================================== --- linux-pm.orig/include/linux/tick.h +++ linux-pm/include/linux/tick.h @@ -119,7 +119,7 @@ extern void tick_nohz_idle_retain_tick(v 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_sleep_length(ktime_t *cur_ret); extern unsigned long tick_nohz_get_idle_calls(void); extern unsigned long tick_nohz_get_idle_calls_cpu(int cpu); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); Index: linux-pm/kernel/time/tick-sched.c =================================================================== --- linux-pm.orig/kernel/time/tick-sched.c +++ linux-pm/kernel/time/tick-sched.c @@ -1031,10 +1031,11 @@ void tick_nohz_irq_exit(void) /** * tick_nohz_get_sleep_length - return the expected length of the current sleep + * @cur_ret: pointer for returning the current time to the next event * * Called from power state control code with interrupts disabled */ -ktime_t tick_nohz_get_sleep_length(void) +ktime_t tick_nohz_get_sleep_length(ktime_t *cur_ret) { struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); @@ -1047,6 +1048,8 @@ ktime_t tick_nohz_get_sleep_length(void) WARN_ON_ONCE(!ts->inidle); + *cur_ret = ktime_sub(dev->next_event, now); + if (can_stop_idle_tick(cpu, ts)) { ktime_t next_event = tick_nohz_next_event(ts, cpu); @@ -1054,7 +1057,7 @@ ktime_t tick_nohz_get_sleep_length(void) return ktime_sub(next_event, now); } - return ktime_sub(dev->next_event, now); + return *cur_ret; } /** Index: linux-pm/drivers/cpuidle/governors/menu.c =================================================================== --- linux-pm.orig/drivers/cpuidle/governors/menu.c +++ linux-pm/drivers/cpuidle/governors/menu.c @@ -296,6 +296,7 @@ static int menu_select(struct cpuidle_dr unsigned int expected_interval; unsigned long nr_iowaiters, cpu_load; int resume_latency = dev_pm_qos_raw_read_value(device); + ktime_t tick_time; if (data->needs_update) { menu_update(drv, dev); @@ -313,7 +314,7 @@ static int menu_select(struct cpuidle_dr } /* determine the expected residency time, round up */ - data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length()); + data->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length(&tick_time)); get_iowait_load(&nr_iowaiters, &cpu_load); data->bucket = which_bucket(data->next_timer_us, nr_iowaiters); @@ -400,8 +401,22 @@ static int menu_select(struct cpuidle_dr * within the tick period range that could be used if longer * idle duration was predicted. */ - *nohz_ret = !(first_idx > idx && - drv->states[first_idx].target_residency < TICK_USEC_HZ); + if (first_idx > idx && + drv->states[first_idx].target_residency < TICK_USEC_HZ) { + unsigned int tick_us = ktime_to_us(tick_time); + + /* + * Find a state with target residency less than the + * time to the next timer event including the tick. + */ + while (idx > 0 && + (drv->states[idx].target_residency > tick_us || + drv->states[idx].disabled || + dev->states_usage[idx].disable)) + idx--; + + *nohz_ret = false; + } } data->last_state_idx = idx;