Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261373AbVBFD6i (ORCPT ); Sat, 5 Feb 2005 22:58:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S272756AbVBFD63 (ORCPT ); Sat, 5 Feb 2005 22:58:29 -0500 Received: from ylpvm29-ext.prodigy.net ([207.115.57.60]:11403 "EHLO ylpvm29.prodigy.net") by vger.kernel.org with ESMTP id S271409AbVBFDzV (ORCPT ); Sat, 5 Feb 2005 22:55:21 -0500 Date: Sat, 5 Feb 2005 19:54:18 -0800 From: Tony Lindgren To: Pavel Machek Cc: Benjamin Herrenschmidt , Arjan van de Ven , Martin Schwidefsky , Andrea Arcangeli , George Anzinger , Thomas Gleixner , john stultz , Zwane Mwaikambo , Lee Revell , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Dynamic tick, version 050127-1 Message-ID: <20050206035417.GB15853@atomide.com> References: <20050201204008.GD14274@atomide.com> <20050201212542.GA3691@openzaurus.ucw.cz> <20050201230357.GH14274@atomide.com> <20050202141105.GA1316@elf.ucw.cz> <20050203030359.GL13984@atomide.com> <20050203105647.GA1369@elf.ucw.cz> <20050203164331.GE14325@atomide.com> <20050204051929.GO14325@atomide.com> <20050205230017.GA1070@elf.ucw.cz> <20050206023344.GA15853@atomide.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="bp/iNruPH9dso1Pn" Content-Disposition: inline In-Reply-To: <20050206023344.GA15853@atomide.com> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 21949 Lines: 749 --bp/iNruPH9dso1Pn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline * Tony Lindgren [050205 18:39]: > * Pavel Machek [050205 15:08]: > > > > Ok, works slightly better: time no longer runs 2x too fast. When TSC > > is used, I get same behaviour as before ("sleepy machine"). With > > "notsc", machine seems to work okay, but I still get 1000 timer > > interrupts a second. ... > > Sounds like your system is not running with the dyn-tick... I'll try > to fix that TSC bug. The following patch fixes TSC timer with dyn-tick, and local APIC timer on UP system with CONFIG_SMP. Tony --bp/iNruPH9dso1Pn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="patch-2.6.11-rc3-dyn-tick-050205-1" diff -Nru a/arch/i386/Kconfig b/arch/i386/Kconfig --- a/arch/i386/Kconfig 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/Kconfig 2005-02-05 19:46:47 -08:00 @@ -452,6 +452,16 @@ bool "Provide RTC interrupt" depends on HPET_TIMER && RTC=y +config NO_IDLE_HZ + bool "Dynamic Tick Timer - Skip timer ticks during idle" + help + This option enables support for skipping timer ticks when the + processor is idle. During system load, timer is continuous. + This option saves power, as it allows the system to stay in + idle mode longer. Currently supported timers are ACPI PM + timer, local APIC timer, and TSC timer. HPET timer is currently + not supported. + config SMP bool "Symmetric multi-processing support" ---help--- diff -Nru a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c --- a/arch/i386/kernel/apic.c 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/kernel/apic.c 2005-02-05 19:46:47 -08:00 @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -909,6 +910,8 @@ #define APIC_DIVISOR 16 +static u32 apic_timer_val; + void __setup_APIC_LVTT(unsigned int clocks) { unsigned int lvtt_value, tmp_value, ver; @@ -927,7 +930,15 @@ & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE)) | APIC_TDR_DIV_16); - apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR); + apic_timer_val = clocks/APIC_DIVISOR; + +#ifdef CONFIG_NO_IDLE_HZ + /* Local APIC timer is 24-bit */ + if (apic_timer_val) + dyn_tick->max_skip = 0xffffff / apic_timer_val; +#endif + + apic_write_around(APIC_TMICT, apic_timer_val); } static void setup_APIC_timer(unsigned int clocks) @@ -1040,6 +1051,13 @@ */ setup_APIC_timer(calibration_result); +#ifdef CONFIG_NO_IDLE_HZ + if (calibration_result) + dyn_tick->state |= DYN_TICK_USE_APIC; + else + printk(KERN_INFO "dyn-tick: Cannot use local APIC\n"); +#endif + local_irq_enable(); } @@ -1068,6 +1086,18 @@ } } +#if defined(CONFIG_NO_IDLE_HZ) +void reprogram_apic_timer(unsigned int count) +{ + unsigned long flags; + + count *= apic_timer_val; + local_irq_save(flags); + apic_write_around(APIC_TMICT, count); + local_irq_restore(flags); +} +#endif + /* * the frequency of the profiling timer can be changed * by writing a multiplier value into /proc/profile. @@ -1160,6 +1190,7 @@ fastcall void smp_apic_timer_interrupt(struct pt_regs *regs) { + unsigned long seq; int cpu = smp_processor_id(); /* @@ -1178,6 +1209,23 @@ * interrupt lock, which is the WrongThing (tm) to do. */ irq_enter(); + +#ifdef CONFIG_NO_IDLE_HZ + /* + * Check if we need to wake up PIT interrupt handler. + * Otherwise just wake up local APIC timer. + */ + do { + seq = read_seqbegin(&xtime_lock); + if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING)) { + if (dyn_tick->skip_cpu == cpu && dyn_tick->skip > DYN_TICK_MIN_SKIP) + dyn_tick->interrupt(99, NULL, regs); + else + reprogram_apic_timer(1); + } + } while (read_seqretry(&xtime_lock, seq)); +#endif + smp_local_timer_interrupt(regs); irq_exit(); } diff -Nru a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c --- a/arch/i386/kernel/irq.c 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/kernel/irq.c 2005-02-05 19:46:47 -08:00 @@ -15,6 +15,7 @@ #include #include #include +#include #ifndef CONFIG_X86_LOCAL_APIC /* @@ -100,6 +101,11 @@ } else #endif __do_IRQ(irq, regs); + +#ifdef CONFIG_NO_IDLE_HZ + if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING) && irq != 0) + dyn_tick->interrupt(irq, NULL, regs); +#endif irq_exit(); diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c --- a/arch/i386/kernel/time.c 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/kernel/time.c 2005-02-05 19:46:47 -08:00 @@ -46,6 +46,7 @@ #include #include #include +#include #include #include @@ -301,6 +302,60 @@ return IRQ_HANDLED; } +#ifdef CONFIG_NO_IDLE_HZ +static unsigned long long last_tick; +void reprogram_pit_tick(int jiffies_to_skip); +extern void replace_timer_interrupt(void * new_handler); + +#if defined(CONFIG_NO_IDLE_HZ) && defined(CONFIG_X86_LOCAL_APIC) +extern void reprogram_apic_timer(unsigned int count); +#else +void reprogram_apic_timer(unsigned int count) {} +#endif + +#ifdef DEBUG +#define dbg_dyn_tick_irq() {if (skipped && skipped < dyn_tick->skip) \ + printk("%u/%li ", skipped, dyn_tick->skip);} +#else +#define dbg_dyn_tick_irq() {} +#endif + + + +/* + * This interrupt handler updates the time based on number of jiffies skipped + * It would be somewhat more optimized to have a customa handler in each timer + * using hardware ticks instead of nanoseconds. Note that CONFIG_NO_IDLE_HZ + * currently disables timer fallback on skipped jiffies. + */ +irqreturn_t dyn_tick_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + unsigned long flags; + volatile unsigned long long now; + unsigned int skipped = 0; + write_seqlock_irqsave(&xtime_lock, flags); + now = cur_timer->get_hw_time(); + while (now - last_tick >= NS_TICK_LEN) { + last_tick += NS_TICK_LEN; + cur_timer->mark_offset(); + do_timer_interrupt(irq, NULL, regs); + skipped++; + } + if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING)) { + dbg_dyn_tick_irq(); + dyn_tick->skip = 1; + if (cpu_has_local_apic()) + reprogram_apic_timer(dyn_tick->skip); + reprogram_pit_tick(dyn_tick->skip); + dyn_tick->state |= DYN_TICK_ENABLED; + dyn_tick->state &= ~DYN_TICK_SKIPPING; + } + write_sequnlock_irqrestore(&xtime_lock, flags); + + return IRQ_HANDLED; +} +#endif + /* not static: needed by APM */ unsigned long get_cmos_time(void) { @@ -396,6 +451,72 @@ } #endif +#ifdef CONFIG_NO_IDLE_HZ +static struct dyn_tick_timer arch_ltt; + +#if defined(CONFIG_X86_UP_APIC) || defined(CONFIG_SMP) +void disable_pit_tick(void) +{ + extern spinlock_t i8253_lock; + unsigned long flags; + spin_lock_irqsave(&i8253_lock, flags); + outb_p(0x31, PIT_MODE); /* binary, mode 1, LSB/MSB, ch 0 */ + spin_unlock_irqrestore(&i8253_lock, flags); +} +#endif + +/* + * Reprograms the next timer interrupt + * PIT timer reprogramming code taken from APM code. + * Note that PIT timer is a 16-bit timer, which allows max + * skip of only few seconds. + */ +void reprogram_pit_tick(int jiffies_to_skip) +{ + int skip; + extern spinlock_t i8253_lock; + unsigned long flags; + + skip = jiffies_to_skip * LATCH; + if (skip > 0xffff) { + skip = 0xffff; + } + + spin_lock_irqsave(&i8253_lock, flags); + outb_p(0x34, PIT_MODE); /* binary, mode 2, LSB/MSB, ch 0 */ + outb_p(skip & 0xff, PIT_CH0); /* LSB */ + outb(skip >> 8, PIT_CH0); /* MSB */ + spin_unlock_irqrestore(&i8253_lock, flags); +} + +static int __init dyn_tick_late_init(void) +{ + unsigned long flags; + + if (!cur_timer->get_hw_time) + return -ENODEV; + write_seqlock_irqsave(&xtime_lock, flags); + last_tick = cur_timer->get_hw_time(); + dyn_tick->skip = 1; + if (!cpu_has_local_apic()) + dyn_tick->max_skip = 0xffff/LATCH; /* PIT timer length */ + printk(KERN_INFO "dyn-tick: Maximum ticks to skip limited to %i\n", + dyn_tick->max_skip); + write_sequnlock_irqrestore(&xtime_lock, flags); + + if (cur_timer->late_init) + cur_timer->late_init(); + dyn_tick->interrupt = dyn_tick_timer_interrupt; + replace_timer_interrupt(dyn_tick->interrupt); + + write_seqlock_irqsave(&xtime_lock, flags); + dyn_tick->state |= DYN_TICK_ENABLED; + write_sequnlock_irqrestore(&xtime_lock, flags); + + return 0; +} +#endif + void __init time_init(void) { #ifdef CONFIG_HPET_TIMER @@ -415,6 +536,16 @@ cur_timer = select_timer(); printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name); + +#ifdef CONFIG_NO_IDLE_HZ + if (strncmp(cur_timer->name, "tsc", 3) == 0 || + strncmp(cur_timer->name, "pmtmr", 3) == 0) { + arch_ltt.init = dyn_tick_late_init; + dyn_tick_register(&arch_ltt); + } else + printk(KERN_INFO "dyn-tick: Cannot use timer %s\n", + cur_timer->name); +#endif time_init_hook(); } diff -Nru a/arch/i386/kernel/timers/timer_pm.c b/arch/i386/kernel/timers/timer_pm.c --- a/arch/i386/kernel/timers/timer_pm.c 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/kernel/timers/timer_pm.c 2005-02-05 19:46:47 -08:00 @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -168,6 +169,7 @@ monotonic_base += delta * NSEC_PER_USEC; write_sequnlock(&monotonic_lock); +#ifndef CONFIG_NO_IDLE_HZ /* convert to ticks */ delta += offset_delay; lost = delta / (USEC_PER_SEC / HZ); @@ -184,6 +186,7 @@ first_run = 0; offset_delay = 0; } +#endif } @@ -238,6 +241,25 @@ return (unsigned long) offset_delay + cyc2us(delta); } +static unsigned long long ns_time; + +static unsigned long long get_hw_time_pmtmr(void) +{ + u32 now, delta; + static unsigned int last_cycles; + now = read_pmtmr(); + delta = (now - last_cycles) & ACPI_PM_MASK; + last_cycles = now; + ns_time += cyc2us(delta) * NSEC_PER_USEC; + return ns_time; +} + +static void late_init_pmtmr(void) +{ + ns_time = monotonic_clock_pmtmr(); +} + +extern irqreturn_t pmtmr_interrupt(int irq, void *dev_id, struct pt_regs *regs); /* acpi timer_opts struct */ static struct timer_opts timer_pmtmr = { @@ -245,7 +267,9 @@ .mark_offset = mark_offset_pmtmr, .get_offset = get_offset_pmtmr, .monotonic_clock = monotonic_clock_pmtmr, + .get_hw_time = get_hw_time_pmtmr, .delay = delay_pmtmr, + .late_init = late_init_pmtmr, }; struct init_timer_opts __initdata timer_pmtmr_init = { diff -Nru a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c --- a/arch/i386/kernel/timers/timer_tsc.c 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/kernel/timers/timer_tsc.c 2005-02-05 19:46:47 -08:00 @@ -112,6 +112,15 @@ return delay_at_last_interrupt + edx; } +static unsigned long get_hw_time_tsc(void) +{ + register unsigned long eax, edx; + + unsigned long long hw_time; + rdtscll(hw_time); + return cycles_2_ns(hw_time); +} + static unsigned long long monotonic_clock_tsc(void) { unsigned long long last_offset, this_offset, base; @@ -348,6 +357,7 @@ rdtsc(last_tsc_low, last_tsc_high); +#ifndef CONFIG_NO_IDLE_HZ spin_lock(&i8253_lock); outb_p(0x00, PIT_MODE); /* latch the count ASAP */ @@ -415,11 +425,14 @@ cpufreq_delayed_get(); } else lost_count = 0; +#endif + /* update the monotonic base value */ this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low; monotonic_base += cycles_2_ns(this_offset - last_offset); write_sequnlock(&monotonic_lock); +#ifndef CONFIG_NO_IDLE_HZ /* calculate delay_at_last_interrupt */ count = ((LATCH-1) - count) * TICK_SIZE; delay_at_last_interrupt = (count + LATCH/2) / LATCH; @@ -430,6 +443,7 @@ */ if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ)) jiffies_64++; +#endif } static int __init init_tsc(char* override) @@ -551,6 +565,7 @@ .mark_offset = mark_offset_tsc, .get_offset = get_offset_tsc, .monotonic_clock = monotonic_clock_tsc, + .get_hw_time = get_hw_time_tsc, .delay = delay_tsc, }; diff -Nru a/arch/i386/mach-default/setup.c b/arch/i386/mach-default/setup.c --- a/arch/i386/mach-default/setup.c 2005-02-05 19:46:47 -08:00 +++ b/arch/i386/mach-default/setup.c 2005-02-05 19:46:47 -08:00 @@ -85,6 +85,22 @@ setup_irq(0, &irq0); } +/** + * replace_timer_interrupt - allow replacing timer interrupt handler + * + * Description: + * Can be used to replace timer interrupt handler with a more optimized + * handler. Used for enabling and disabling of CONFIG_NO_IDLE_HZ. + */ +void replace_timer_interrupt(void * new_handler) +{ + unsigned long flags; + + write_seqlock_irqsave(&xtime_lock, flags); + irq0.handler = new_handler; + write_sequnlock_irqrestore(&xtime_lock, flags); +} + #ifdef CONFIG_MCA /** * mca_nmi_hook - hook into MCA specific NMI chain diff -Nru a/include/asm-i386/timer.h b/include/asm-i386/timer.h --- a/include/asm-i386/timer.h 2005-02-05 19:46:47 -08:00 +++ b/include/asm-i386/timer.h 2005-02-05 19:46:47 -08:00 @@ -1,6 +1,7 @@ #ifndef _ASMi386_TIMER_H #define _ASMi386_TIMER_H #include +#include /** * struct timer_ops - used to define a timer source @@ -21,7 +22,9 @@ void (*mark_offset)(void); unsigned long (*get_offset)(void); unsigned long long (*monotonic_clock)(void); + unsigned long long (*get_hw_time)(void); void (*delay)(unsigned long); + void (*late_init)(void); }; struct init_timer_opts { diff -Nru a/include/linux/dyn-tick-timer.h b/include/linux/dyn-tick-timer.h --- /dev/null Wed Dec 31 16:00:00 196900 +++ b/include/linux/dyn-tick-timer.h 2005-02-05 19:46:47 -08:00 @@ -0,0 +1,71 @@ +/* + * linux/include/linux/dyn-tick-timer.h + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen and + * Tuukka Tikkanen + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN + * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include + +#define DYN_TICK_USE_APIC (1 << 2) +#define DYN_TICK_SKIPPING (1 << 1) +#define DYN_TICK_ENABLED (1 << 0) + +struct dyn_tick_state { + unsigned int state; /* Current state */ + int skip_cpu; /* Skip handling processor */ + unsigned long skip; /* Ticks to skip */ + unsigned int max_skip; /* Max number of ticks to skip */ + unsigned long irq_skip_mask; /* Do not update time from these irqs */ + irqreturn_t (*interrupt)(int, void *, struct pt_regs *); +}; + +/* REVISIT: Add functions to enable/disable dyn-tick on the fly */ +struct dyn_tick_timer { + int (*init) (void); +}; + +extern struct dyn_tick_state * dyn_tick; +extern void dyn_tick_register(struct dyn_tick_timer * new_timer); + +#define NS_TICK_LEN ((1 * 1000000000)/HZ) +#define DYN_TICK_MIN_SKIP 2 + +#if defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC) +#define cpu_has_local_apic() (dyn_tick->state & DYN_TICK_USE_APIC) +#else +#define cpu_has_local_apic() 0 +#endif + +#ifdef CONFIG_NO_IDLE_HZ + +#if defined(CONFIG_X86) || defined(CONFIG_IA64) || defined(CONFIG_X86_64) +#define arch_has_safe_halt() 1 +#endif + +#else + +#define arch_has_safe_halt() 0 + +#endif diff -Nru a/kernel/Makefile b/kernel/Makefile --- a/kernel/Makefile 2005-02-05 19:46:47 -08:00 +++ b/kernel/Makefile 2005-02-05 19:46:47 -08:00 @@ -26,6 +26,7 @@ obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_SYSFS) += ksysfs.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ +obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick-timer.o ifneq ($(CONFIG_IA64),y) # According to Alan Modra , the -fno-omit-frame-pointer is diff -Nru a/kernel/dyn-tick-timer.c b/kernel/dyn-tick-timer.c --- /dev/null Wed Dec 31 16:00:00 196900 +++ b/kernel/dyn-tick-timer.c 2005-02-05 19:46:47 -08:00 @@ -0,0 +1,149 @@ +/* + * linux/arch/i386/kernel/dyn-tick.c + * + * Beginnings of generic dynamic tick timer support + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen and + * Tuukka Tikkanen + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN + * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF + * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 675 Mass Ave, Cambridge, MA 02139, USA. + * + * + * TODO: + * - Add functions for enabling/disabling dyn-tick on the fly + * - Generalize to work with ARM sys_timer + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "io_ports.h" + +#define VERSION 050205-1 + +struct dyn_tick_state dyn_tick_state; +struct dyn_tick_state * dyn_tick = &dyn_tick_state; +struct dyn_tick_timer dyn_tick_timer; +struct dyn_tick_timer * dyn_tick_cfg = &dyn_tick_timer; +static void (*orig_idle) (void) = 0; +extern void disable_pit_tick(void); +extern void reprogram_pit_tick(int jiffies_to_skip); +extern void reprogram_apic_timer(unsigned int count); +extern void reprogram_pit_tick(int jiffies_to_skip); +static cpumask_t dyn_cpu_map; + +/* + * We want to have all processors idle before reprogramming the next + * timer interrupt. Note that we must maintain the state for dynamic tick, + * otherwise the idle loop could be reprogramming the timer continuously + * further into the future, and the timer interrupt would never happen. + */ +static void dyn_tick_idle(void) +{ + int cpu; + unsigned long flags; + cpumask_t idle_cpus; + unsigned long next; + + if (!(dyn_tick->state & DYN_TICK_ENABLED)) + goto out; + + /* Check if we are already skipping ticks and can idle other cpus */ + if (dyn_tick->state & DYN_TICK_SKIPPING) { + reprogram_apic_timer(dyn_tick->skip); + goto out; + } + + /* Check if we can start skipping ticks */ + write_seqlock_irqsave(&xtime_lock, flags); + cpu = smp_processor_id(); + cpu_set(cpu, dyn_cpu_map); + cpus_and(idle_cpus, dyn_cpu_map, cpu_online_map); + if (cpus_equal(idle_cpus, cpu_online_map)) { + next = next_timer_interrupt(); + if (jiffies > next) { + //printk("Too late? next: %lu jiffies: %lu\n", + // next, jjiffies); + dyn_tick->skip = 1; + } else + dyn_tick->skip = next_timer_interrupt() - jiffies; + if (dyn_tick->skip > DYN_TICK_MIN_SKIP) { + if (dyn_tick->skip > dyn_tick->max_skip) + dyn_tick->skip = dyn_tick->max_skip; + if (cpu_has_local_apic()) { + disable_pit_tick(); + reprogram_apic_timer(dyn_tick->skip); + } else + reprogram_pit_tick(dyn_tick->skip); + dyn_tick->skip_cpu = cpu; + dyn_tick->state |= DYN_TICK_SKIPPING; + } + cpus_clear(dyn_cpu_map); + } + write_sequnlock_irqrestore(&xtime_lock, flags); + +out: + if (orig_idle) + orig_idle(); + else if (arch_has_safe_halt()) + safe_halt(); +} + +void __init dyn_tick_register(struct dyn_tick_timer * new_timer) +{ + dyn_tick_cfg->init = new_timer->init; + printk(KERN_INFO "dyn-tick: Registering dynamic tick timer\n"); +} + +/* + * We need to initialize dynamic tick after calibrate delay + */ +static int __init dyn_tick_init(void) +{ + int ret = 0; + + if (dyn_tick_cfg->init == NULL) + return -ENODEV; + + ret = dyn_tick_cfg->init(); + if (ret != 0) { + printk(KERN_WARNING "dyn-tick: Init failed\n"); + return -ENODEV; + } + orig_idle = pm_idle; + pm_idle = dyn_tick_idle; +#if (LINUX_VERSION_CODE > KERNEL_VERSION(2,6,10)) + cpu_idle_wait(); +#endif + printk(KERN_INFO "dyn-tick: Timer using dynamic tick\n"); + + return ret; +} +late_initcall(dyn_tick_init); --bp/iNruPH9dso1Pn-- - 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/