From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966161AbbDVTKm (ORCPT ); Wed, 22 Apr 2015 15:10:42 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41451 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757414AbbDVTKj (ORCPT ); Wed, 22 Apr 2015 15:10:39 -0400 Date: Wed, 22 Apr 2015 12:09:56 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: viresh.kumar@linaro.org, tglx@linutronix.de, mingo@kernel.org, john.stultz@linaro.org, preeti@linux.vnet.ibm.com, fweisbec@gmail.com, peterz@infradead.org, mtosatti@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com Reply-To: hpa@zytor.com, linux-kernel@vger.kernel.org, mtosatti@redhat.com, peterz@infradead.org, fweisbec@gmail.com, preeti@linux.vnet.ibm.com, john.stultz@linaro.org, mingo@kernel.org, tglx@linutronix.de, viresh.kumar@linaro.org In-Reply-To: <20150414203502.101563235@linutronix.de> References: <20150414203502.101563235@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] tick: Sched: Restructure code Git-Commit-ID: 157d29e101c7d032e886df067aeea1b21a366cc5 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 157d29e101c7d032e886df067aeea1b21a366cc5 Gitweb: http://git.kernel.org/tip/157d29e101c7d032e886df067aeea1b21a366cc5 Author: Thomas Gleixner AuthorDate: Tue, 14 Apr 2015 21:08:56 +0000 Committer: Thomas Gleixner CommitDate: Wed, 22 Apr 2015 17:06:50 +0200 tick: Sched: Restructure code Get rid of one indentation level. Preparatory patch for a major rework. No functional change. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Cc: Preeti U Murthy Cc: Viresh Kumar Cc: Marcelo Tosatti Cc: Frederic Weisbecker Cc: John Stultz Cc: Marcelo Tosatti Link: http://lkml.kernel.org/r/20150414203502.101563235@linutronix.de Signed-off-by: Thomas Gleixner --- kernel/time/tick-sched.c | 171 ++++++++++++++++++++++------------------------- 1 file changed, 81 insertions(+), 90 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 0f07ff2..4c5f4a9 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -611,112 +611,103 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, } } + if ((long)delta_jiffies <= 1) { + if (!ts->tick_stopped) + goto out; + if (delta_jiffies == 0) { + /* Tick is stopped, but required now. Enforce it */ + tick_nohz_restart(ts, now); + goto out; + } + } + /* - * Do not stop the tick, if we are only one off (or less) - * or if the cpu is required for RCU: + * If this cpu is the one which updates jiffies, then give up + * the assignment and let it be taken by the cpu which runs + * the tick timer next, which might be this cpu as well. If we + * don't drop this here the jiffies might be stale and + * do_timer() never invoked. Keep track of the fact that it + * was the one which had the do_timer() duty last. If this cpu + * is the one which had the do_timer() duty last, we limit the + * sleep time to the timekeeping max_deferement value which we + * retrieved above. Otherwise we can sleep as long as we want. */ - if (!ts->tick_stopped && delta_jiffies <= 1) - goto out; - - /* Schedule the tick, if we are at least one jiffie off */ - if ((long)delta_jiffies >= 1) { - - /* - * If this cpu is the one which updates jiffies, then - * give up the assignment and let it be taken by the - * cpu which runs the tick timer next, which might be - * this cpu as well. If we don't drop this here the - * jiffies might be stale and do_timer() never - * invoked. Keep track of the fact that it was the one - * which had the do_timer() duty last. If this cpu is - * the one which had the do_timer() duty last, we - * limit the sleep time to the timekeeping - * max_deferement value which we retrieved - * above. Otherwise we can sleep as long as we want. - */ - if (cpu == tick_do_timer_cpu) { - tick_do_timer_cpu = TICK_DO_TIMER_NONE; - ts->do_timer_last = 1; - } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { - time_delta = KTIME_MAX; - ts->do_timer_last = 0; - } else if (!ts->do_timer_last) { - time_delta = KTIME_MAX; - } + if (cpu == tick_do_timer_cpu) { + tick_do_timer_cpu = TICK_DO_TIMER_NONE; + ts->do_timer_last = 1; + } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { + time_delta = KTIME_MAX; + ts->do_timer_last = 0; + } else if (!ts->do_timer_last) { + time_delta = KTIME_MAX; + } #ifdef CONFIG_NO_HZ_FULL - if (!ts->inidle) { - time_delta = min(time_delta, - scheduler_tick_max_deferment()); - } + if (!ts->inidle) + time_delta = min(time_delta, scheduler_tick_max_deferment()); #endif + /* + * calculate the expiry time for the next timer wheel + * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that + * there is no timer pending or at least extremely far into + * the future (12 days for HZ=1000). In this case we set the + * expiry to the end of time. + */ + if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) { /* - * calculate the expiry time for the next timer wheel - * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals - * that there is no timer pending or at least extremely - * far into the future (12 days for HZ=1000). In this - * case we set the expiry to the end of time. + * Calculate the time delta for the next timer event. + * If the time delta exceeds the maximum time delta + * permitted by the current clocksource then adjust + * the time delta accordingly to ensure the + * clocksource does not wrap. */ - if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) { - /* - * Calculate the time delta for the next timer event. - * If the time delta exceeds the maximum time delta - * permitted by the current clocksource then adjust - * the time delta accordingly to ensure the - * clocksource does not wrap. - */ - time_delta = min_t(u64, time_delta, - tick_period.tv64 * delta_jiffies); - } - - if (time_delta < KTIME_MAX) - expires = ktime_add_ns(last_update, time_delta); - else - expires.tv64 = KTIME_MAX; + time_delta = min_t(u64, time_delta, + tick_period.tv64 * delta_jiffies); + } - /* Skip reprogram of event if its not changed */ - if (ts->tick_stopped && ktime_equal(expires, dev->next_event)) - goto out; + if (time_delta < KTIME_MAX) + expires = ktime_add_ns(last_update, time_delta); + else + expires.tv64 = KTIME_MAX; - ret = expires; + /* Skip reprogram of event if its not changed */ + if (ts->tick_stopped && ktime_equal(expires, dev->next_event)) + goto out; - /* - * nohz_stop_sched_tick can be called several times before - * the nohz_restart_sched_tick is called. This happens when - * interrupts arrive which do not cause a reschedule. In the - * first call we save the current tick time, so we can restart - * the scheduler tick in nohz_restart_sched_tick. - */ - if (!ts->tick_stopped) { - nohz_balance_enter_idle(cpu); - calc_load_enter_idle(); + ret = expires; - ts->last_tick = hrtimer_get_expires(&ts->sched_timer); - ts->tick_stopped = 1; - trace_tick_stop(1, " "); - } + /* + * nohz_stop_sched_tick can be called several times before + * the nohz_restart_sched_tick is called. This happens when + * interrupts arrive which do not cause a reschedule. In the + * first call we save the current tick time, so we can restart + * the scheduler tick in nohz_restart_sched_tick. + */ + if (!ts->tick_stopped) { + nohz_balance_enter_idle(cpu); + calc_load_enter_idle(); - /* - * If the expiration time == KTIME_MAX, then - * in this case we simply stop the tick timer. - */ - if (unlikely(expires.tv64 == KTIME_MAX)) { - if (ts->nohz_mode == NOHZ_MODE_HIGHRES) - hrtimer_cancel(&ts->sched_timer); - goto out; - } + ts->last_tick = hrtimer_get_expires(&ts->sched_timer); + ts->tick_stopped = 1; + trace_tick_stop(1, " "); + } - if (ts->nohz_mode == NOHZ_MODE_HIGHRES) - hrtimer_start(&ts->sched_timer, expires, - HRTIMER_MODE_ABS_PINNED); - else - tick_program_event(expires, 1); - } else { - /* Tick is stopped, but required now. Enforce it */ - tick_nohz_restart(ts, now); + /* + * If the expiration time == KTIME_MAX, then + * in this case we simply stop the tick timer. + */ + if (unlikely(expires.tv64 == KTIME_MAX)) { + if (ts->nohz_mode == NOHZ_MODE_HIGHRES) + hrtimer_cancel(&ts->sched_timer); + goto out; } + if (ts->nohz_mode == NOHZ_MODE_HIGHRES) + hrtimer_start(&ts->sched_timer, expires, + HRTIMER_MODE_ABS_PINNED); + else + tick_program_event(expires, 1); out: ts->next_jiffies = next_jiffies; ts->last_jiffies = last_jiffies;