Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752412AbXA1CDo (ORCPT ); Sat, 27 Jan 2007 21:03:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752411AbXA1CDo (ORCPT ); Sat, 27 Jan 2007 21:03:44 -0500 Received: from mout2.freenet.de ([194.97.50.155]:48458 "EHLO mout2.freenet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751873AbXA1CDn (ORCPT ); Sat, 27 Jan 2007 21:03:43 -0500 From: Karsten Wiese To: Thomas Gleixner Subject: [PATCH] high_res_timers: precisely update_process_times; Re: [patch 36/46] tick-management: dyntick / highres functionality Date: Sun, 28 Jan 2007 03:03:35 +0100 User-Agent: KMail/1.9.5 Cc: Andrew Morton , LKML , Ingo Molnar , John Stultz , Arjan van de Veen , Roman Zippel References: <20070123211159.178138000@localhost.localdomain> <20070123211208.550932000@localhost.localdomain> In-Reply-To: <20070123211208.550932000@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200701280303.36441.fzu@wemgehoertderstaat.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6427 Lines: 186 Am Dienstag, 23. Januar 2007 23:01 schrieb Thomas Gleixner: > > Add functions to provide dynamic ticks and high resolution timers. > The code which keeps track of jiffies and handles the long idle > periods is shared between tick based and high resolution timer based > dynticks. The dyntick functionality can be disabled on the kernel > commandline. Provide also the infrastructure to support high resolution > timers. cpufreq_ondemand didn't work here on kernels 2.6.20-rc4-rt1 and above. Following patch against 20-rc6-rt2 helps. Karsten ------------------------------------------------------------------------------- From: Karsten Wiese high_res_timers: precisely update_process_times Sometimes tick_sched_timer() calls tick_do_update_jiffies64() and jiffies is updated by !=1. Cope with these situations by splitting update_process_times() into __update_process_times() and tick() and exchanging call to update_process_times() from tick_sched_timer() by calls to the splits. Fixes cpufreq_ondemand going nuts here. Signed-off-by: Karsten Wiese --- rc6-rt2/include/linux/sched.h 2007-01-26 14:42:55.000000000 +0100 +++ rc6-rt2-kw/include/linux/sched.h 2007-01-28 02:02:29.000000000 +0100 @@ -264,6 +264,13 @@ long io_schedule_timeout(long timeout); extern void cpu_init (void); extern void trap_init(void); extern void update_process_times(int user); +#ifdef CONFIG_HIGH_RES_TIMERS +extern void __update_process_times(int user_tick, unsigned long ticks); +extern void tick(int user_tick); +#define NO_HIGH_RES_TIMERS_STATIC +#else +#define NO_HIGH_RES_TIMERS_STATIC static +#endif extern void scheduler_tick(void); #ifdef CONFIG_GENERIC_HARDIRQS diff -pur rc6-rt2/kernel/time/tick-sched.c rc6-rt2-kw/kernel/time/tick-sched.c --- rc6-rt2/kernel/time/tick-sched.c 2007-01-26 14:42:55.000000000 +0100 +++ rc6-rt2-kw/kernel/time/tick-sched.c 2007-01-28 01:45:14.000000000 +0100 @@ -41,9 +41,9 @@ struct tick_sched *tick_get_tick_sched(i /* * Must be called with interrupts disabled ! */ -static void tick_do_update_jiffies64(ktime_t now) +static unsigned long tick_do_update_jiffies64(ktime_t now) { - unsigned long ticks = 1; + unsigned long ticks = 0; ktime_t delta; /* Reevalute with xtime_lock held */ @@ -51,7 +51,7 @@ static void tick_do_update_jiffies64(kti delta = ktime_sub(now, last_jiffies_update); if (delta.tv64 >= tick_period.tv64) { - + ticks = 1; delta = ktime_sub(delta, tick_period); last_jiffies_update = ktime_add(last_jiffies_update, tick_period); @@ -68,6 +68,7 @@ static void tick_do_update_jiffies64(kti do_timer(ticks); } write_sequnlock(&xtime_lock); + return ticks; } /* @@ -423,32 +424,36 @@ static enum hrtimer_restart tick_sched_t ktime_t now = ktime_get(); /* Check, if the jiffies need an update */ - tick_do_update_jiffies64(now); + unsigned long ticks = tick_do_update_jiffies64(now); /* * Do not call, when we are not in irq context and have * no valid regs pointer */ if (regs) { - /* - * When we are idle and the tick is stopped, we have to touch - * the watchdog as we might not schedule for a really long - * time. This happens on complete idle SMP systems while - * waiting on the login prompt. We also increment the "start of - * idle" jiffy stamp so the idle accounting adjustment we do - * when we go busy again does not account too much ticks. - */ - if (ts->tick_stopped) { - touch_softlockup_watchdog(); - ts->idle_jiffies++; + if (ticks) { + /* + * When we are idle and the tick is stopped, we have to touch + * the watchdog as we might not schedule for a really long + * time. This happens on complete idle SMP systems while + * waiting on the login prompt. We also increment the "start of + * idle" jiffy stamp so the idle accounting adjustment we do + * when we go busy again does not account too much ticks. + */ + if (ts->tick_stopped) { + touch_softlockup_watchdog(); + ts->idle_jiffies++; + __update_process_times(user_mode(regs), 1); + } else + __update_process_times(user_mode(regs), ticks); } /* - * update_process_times() might take tasklist_lock, hence + * tick() might take tasklist_lock, hence * drop the base lock. sched-tick hrtimers are per-CPU and * never accessible by userspace APIs, so this is safe to do. */ spin_unlock(&base->lock); - update_process_times(user_mode(regs)); + tick(user_mode(regs)); // profile_tick(CPU_PROFILING); spin_lock(&base->lock); } diff -pur rc6-rt2/kernel/timer.c rc6-rt2-kw/kernel/timer.c --- rc6-rt2/kernel/timer.c 2007-01-26 14:42:55.000000000 +0100 +++ rc6-rt2-kw/kernel/timer.c 2007-01-28 02:03:01.000000000 +0100 @@ -1312,20 +1312,24 @@ static void update_wall_time(void) update_vsyscall(&xtime, clock); } -/* - * Called from the timer interrupt handler to charge one tick to the current - * process. user_tick is 1 if the tick is user time, 0 for system. - */ -void update_process_times(int user_tick) +NO_HIGH_RES_TIMERS_STATIC +void __update_process_times(int user_tick, unsigned long ticks) { - int cpu = smp_processor_id(); struct task_struct *p = current; /* Note: this timer irq context must be accounted for as well. */ if (user_tick) - account_user_time(p, jiffies_to_cputime(1)); + account_user_time(p, jiffies_to_cputime(ticks)); else - account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1)); + account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(ticks)); +} + +NO_HIGH_RES_TIMERS_STATIC +void tick(int user_tick) +{ + int cpu = smp_processor_id(); + struct task_struct *p = current; + scheduler_tick(); run_local_timers(); if (rcu_pending(cpu)) @@ -1334,6 +1338,16 @@ void update_process_times(int user_tick) } /* + * Called from the timer interrupt handler to charge one tick to the current + * process. user_tick is 1 if the tick is user time, 0 for system. + */ +void update_process_times(int user_tick) +{ + __update_process_times(user_tick, 1); + tick(user_tick); +} + +/* * Nr of active tasks - counted in fixed-point numbers */ static unsigned long count_active_tasks(void) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/