Index: linux-dev/arch/i386/Kconfig =================================================================== --- linux-dev.orig/arch/i386/Kconfig 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/Kconfig 2005-06-10 11:39:09.000000000 -0700 @@ -458,6 +458,38 @@ 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. + + Note that you need to enable dynamic tick timer either by + passing dyntick=enable command line option, or via sysfs: + + # echo 1 > /sys/devices/system/timer/timer0/dyn_tick_state + +config DYN_TICK_USE_APIC + bool "Use APIC timer instead of PIT timer" + depends on NO_IDLE_HZ + help + This option enables using APIC timer interrupt if your hardware + supports it. APIC timer allows longer sleep periods compared + to PIT timer. + + Note that on most recent hardware disabling PIT timer also + disables APIC timer interrupts, and system won't run properly. + Symptoms include slow system boot, and time running slow. + + If unsure, don't enable this option. + + Note that to you still need to pass dyntick=enable,forceapic + command line option to use APIC timer. + config SMP bool "Symmetric multi-processing support" ---help--- Index: linux-dev/arch/i386/kernel/Makefile =================================================================== --- linux-dev.orig/arch/i386/kernel/Makefile 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/Makefile 2005-06-10 10:36:12.000000000 -0700 @@ -31,6 +31,7 @@ obj-y += sysenter.o vsyscall.o obj-$(CONFIG_ACPI_SRAT) += srat.o obj-$(CONFIG_HPET_TIMER) += time_hpet.o +obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick.o obj-$(CONFIG_EFI) += efi.o efi_stub.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o Index: linux-dev/arch/i386/kernel/apic.c =================================================================== --- linux-dev.orig/arch/i386/kernel/apic.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/apic.c 2005-06-10 10:36:12.000000000 -0700 @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -909,6 +910,8 @@ #define APIC_DIVISOR 16 +static u32 apic_timer_val; + static 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 __init 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(); } Index: linux-dev/arch/i386/kernel/dyn-tick.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-dev/arch/i386/kernel/dyn-tick.c 2005-06-10 10:36:12.000000000 -0700 @@ -0,0 +1,45 @@ +/* + * linux/arch/i386/kernel/dyn-tick.c + * + * 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 version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include + +void arch_reprogram_timer(void) +{ + if (cpu_has_local_apic()) { + disable_pit_timer(); + if (dyn_tick->state & DYN_TICK_TIMER_INT) + reprogram_apic_timer(dyn_tick->skip); + } else { + if (dyn_tick->state & DYN_TICK_TIMER_INT) + reprogram_pit_timer(dyn_tick->skip); + else + disable_pit_timer(); + } +} + +static struct dyn_tick_timer arch_dyn_tick_timer = { + .arch_reprogram_timer = &arch_reprogram_timer, +}; + +int __init dyn_tick_init(void) +{ + arch_dyn_tick_timer.arch_init = dyn_tick_arch_init; + dyn_tick_register(&arch_dyn_tick_timer); + + return 0; +} +arch_initcall(dyn_tick_init); Index: linux-dev/include/asm-i386/dyn-tick.h =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-dev/include/asm-i386/dyn-tick.h 2005-06-10 10:36:12.000000000 -0700 @@ -0,0 +1,34 @@ +/* + * linux/include/asm-i386/dyn-tick.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 version 2 as + * published by the Free Software Foundation. + */ + +#ifndef _ASM_I386_DYN_TICK_H_ +#define _ASM_I386_DYN_TICK_H_ + +extern int dyn_tick_arch_init(void); +extern void disable_pit_timer(void); +extern void reprogram_pit_timer(int jiffies_to_skip); +extern void reprogram_apic_timer(unsigned int count); +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 +#define reprogram_apic_timer(x) do {} while (0) +#endif + +#if defined(CONFIG_DYN_TICK_USE_APIC) && (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 + +#endif /* _ASM_I386_DYN_TICK_H_ */ Index: linux-dev/arch/i386/kernel/irq.c =================================================================== --- linux-dev.orig/arch/i386/kernel/irq.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/irq.c 2005-06-10 10:36:12.000000000 -0700 @@ -15,6 +15,7 @@ #include #include #include +#include DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_maxaligned_in_smp; EXPORT_PER_CPU_SYMBOL(irq_stat); @@ -73,6 +74,11 @@ } #endif +#ifdef CONFIG_NO_IDLE_HZ + if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING) && irq != 0) + dyn_tick->interrupt(irq, NULL, regs); +#endif + #ifdef CONFIG_4KSTACKS curctx = (union irq_ctx *) current_thread_info(); Index: linux-dev/arch/i386/kernel/process.c =================================================================== --- linux-dev.orig/arch/i386/kernel/process.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/process.c 2005-06-10 10:36:12.000000000 -0700 @@ -37,6 +37,7 @@ #include #include #include +#include #include #include @@ -160,6 +161,8 @@ if (!idle) idle = default_idle; + dyn_tick_reprogram_timer(); + __get_cpu_var(irq_stat).idle_timestamp = jiffies; idle(); } Index: linux-dev/arch/i386/kernel/time.c =================================================================== --- linux-dev.orig/arch/i386/kernel/time.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/time.c 2005-06-10 11:35:31.000000000 -0700 @@ -46,6 +46,7 @@ #include #include #include +#include #include #include @@ -308,6 +309,43 @@ return IRQ_HANDLED; } +#ifdef CONFIG_NO_IDLE_HZ +static unsigned long long last_tick; + +/* + * 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->monotonic_clock(); + 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)) { + dyn_tick->skip = 1; + if (cpu_has_local_apic()) + reprogram_apic_timer(dyn_tick->skip); + reprogram_pit_timer(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 /* CONFIG_NO_IDLE_HZ */ + /* not static: needed by APM */ unsigned long get_cmos_time(void) { @@ -416,7 +454,7 @@ /* XXX this driverfs stuff should probably go elsewhere later -john */ -static struct sys_device device_timer = { +struct sys_device device_timer = { .id = 0, .cls = &timer_sysclass, }; @@ -452,6 +490,28 @@ } #endif +#ifdef CONFIG_NO_IDLE_HZ + +int __init dyn_tick_arch_init(void) +{ + unsigned long flags; + + write_seqlock_irqsave(&xtime_lock, flags); + last_tick = cur_timer->monotonic_clock(); + dyn_tick->skip = 1; + if (!(dyn_tick->state & DYN_TICK_USE_APIC) || !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); + + dyn_tick->interrupt = dyn_tick_timer_interrupt; + replace_timer_interrupt(dyn_tick->interrupt); + + return 0; +} +#endif /* CONFIG_NO_IDLE_HZ */ + void __init time_init(void) { #ifdef CONFIG_HPET_TIMER @@ -472,5 +532,16 @@ 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) { + dyn_tick->state |= DYN_TICK_SUITABLE; + printk(KERN_INFO "dyn-tick: Found suitable timer: %s\n", + cur_timer->name); + } else + printk(KERN_ERR "dyn-tick: Cannot use timer %s\n", + cur_timer->name); +#endif + time_init_hook(); } Index: linux-dev/arch/i386/kernel/timers/timer_pm.c =================================================================== --- linux-dev.orig/arch/i386/kernel/timers/timer_pm.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/timers/timer_pm.c 2005-06-10 11:47:30.000000000 -0700 @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -168,6 +169,9 @@ monotonic_base += delta * NSEC_PER_USEC; write_sequnlock(&monotonic_lock); + if (dyn_tick_enabled()) + return; + /* convert to ticks */ delta += offset_delay; lost = delta / (USEC_PER_SEC / HZ); Index: linux-dev/arch/i386/kernel/timers/timer_tsc.c =================================================================== --- linux-dev.orig/arch/i386/kernel/timers/timer_tsc.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/timers/timer_tsc.c 2005-06-10 11:53:04.000000000 -0700 @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -368,6 +369,9 @@ rdtsc(last_tsc_low, last_tsc_high); + if (dyn_tick_enabled()) + goto monotonic_base; + spin_lock(&i8253_lock); outb_p(0x00, PIT_MODE); /* latch the count ASAP */ @@ -435,11 +439,17 @@ cpufreq_delayed_get(); } else lost_count = 0; + + monotonic_base: + /* 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); + if (dyn_tick_enabled()) + return; + /* calculate delay_at_last_interrupt */ count = ((LATCH-1) - count) * TICK_SIZE; delay_at_last_interrupt = (count + LATCH/2) / LATCH; Index: linux-dev/arch/i386/mach-default/setup.c =================================================================== --- linux-dev.orig/arch/i386/mach-default/setup.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/mach-default/setup.c 2005-06-10 10:36:12.000000000 -0700 @@ -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 Index: linux-dev/include/linux/dyn-tick.h =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-dev/include/linux/dyn-tick.h 2005-06-10 11:48:08.000000000 -0700 @@ -0,0 +1,64 @@ +/* + * linux/include/linux/dyn-tick.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 version 2 as + * published by the Free Software Foundation. + */ + +#ifndef _DYN_TICK_TIMER_H +#define _DYN_TICK_TIMER_H + +#include + +#define DYN_TICK_TIMER_INT (1 << 4) +#define DYN_TICK_USE_APIC (1 << 3) +#define DYN_TICK_SKIPPING (1 << 2) +#define DYN_TICK_ENABLED (1 << 1) +#define DYN_TICK_SUITABLE (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 *); +}; + +struct dyn_tick_timer { + int (*arch_init) (void); + void (*arch_enable) (void); + void (*arch_disable) (void); + void (*arch_reprogram_timer) (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 + + +#ifdef CONFIG_NO_IDLE_HZ + +extern unsigned long dyn_tick_reprogram_timer(void); +#define dyn_tick_enabled() (dyn_tick->state & DYN_TICK_ENABLED) + +#else + +#define arch_has_safe_halt() 0 +#define dyn_tick_reprogram_timer() do {} while (0) +#define dyn_tick_enabled() 0 + +#endif /* CONFIG_NO_IDLE_HZ */ + + +/* Pick up arch specific header */ +#include + +#endif /* _DYN_TICK_TIMER_H */ Index: linux-dev/kernel/Makefile =================================================================== --- linux-dev.orig/kernel/Makefile 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/kernel/Makefile 2005-06-10 10:36:12.000000000 -0700 @@ -28,6 +28,7 @@ obj-$(CONFIG_SYSFS) += ksysfs.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_SECCOMP) += seccomp.o +obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick.o ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y) # According to Alan Modra , the -fno-omit-frame-pointer is Index: linux-dev/kernel/dyn-tick.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-dev/kernel/dyn-tick.c 2005-06-10 11:35:31.000000000 -0700 @@ -0,0 +1,212 @@ +/* + * 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 version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "io_ports.h" + +#define DYN_TICK_VERSION "050610-1" + +struct dyn_tick_state dyn_tick_state; +struct dyn_tick_state * dyn_tick = &dyn_tick_state; +struct dyn_tick_timer * dyn_tick_cfg; +static cpumask_t dyn_cpu_map; + +/* + * Arch independed code needed to reprogram next timer interrupt. + * Gets called from cpu_idle() before entering idle loop. Note that + * we want to have all processors idle before reprogramming the + * next timer interrupt. + */ +unsigned long dyn_tick_reprogram_timer(void) +{ + int cpu; + unsigned long flags; + cpumask_t idle_cpus; + unsigned long next; + + if (!(dyn_tick->state & DYN_TICK_ENABLED)) + return 0; + + /* Check if we are already skipping ticks and can idle other cpus */ + if (dyn_tick->state & DYN_TICK_SKIPPING) { + if (cpu_has_local_apic()) + reprogram_apic_timer(dyn_tick->skip); + return 0; + } + + /* 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) + 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; + + dyn_tick_cfg->arch_reprogram_timer(); + + dyn_tick->skip_cpu = cpu; + dyn_tick->state |= DYN_TICK_SKIPPING; + } + cpus_clear(dyn_cpu_map); + } + write_sequnlock_irqrestore(&xtime_lock, flags); + + return dyn_tick->skip; +} + +void __init dyn_tick_register(struct dyn_tick_timer * arch_timer) +{ + dyn_tick_cfg = arch_timer; + printk(KERN_INFO "dyn-tick: Registering dynamic tick timer v%s\n", + DYN_TICK_VERSION); +} + +/* + * --------------------------------------------------------------------------- + * Command line options + * --------------------------------------------------------------------------- + */ +static int __initdata dyntick_autoenable = 0; +static int __initdata dyntick_useapic = 0; + +/* + * dyntick=[enable|disable],[forceapic] + */ +static int __init dyntick_setup(char *options) +{ + if (!options) + return 0; + + if (!strncmp(options, "enable", 6)) + dyntick_autoenable = 1; + + if (strstr(options, "forceapic")) + dyntick_useapic = 1; + + return 0; +} + +__setup("dyntick=", dyntick_setup); + +/* + * --------------------------------------------------------------------------- + * Sysfs interface + * --------------------------------------------------------------------------- + */ + +extern struct sys_device device_timer; + +#define DYN_TICK_IS_SET(x) ((dyn_tick->state & (x)) == (x)) + +static ssize_t show_dyn_tick_state(struct sys_device *dev, char *buf) +{ + return sprintf(buf, + "suitable:\t%i\n" + "enabled:\t%i\n" + "using APIC:\t%i\n", + DYN_TICK_IS_SET(DYN_TICK_SUITABLE), + DYN_TICK_IS_SET(DYN_TICK_ENABLED), + DYN_TICK_IS_SET(DYN_TICK_USE_APIC)); +} + +static ssize_t set_dyn_tick_state(struct sys_device *dev, const char * buf, + size_t count) +{ + unsigned long flags; + unsigned int enable = simple_strtoul(buf, NULL, 2); + + write_seqlock_irqsave(&xtime_lock, flags); + if (enable) { + if (dyn_tick_cfg->arch_enable) + dyn_tick_cfg->arch_enable(); + dyn_tick->state |= DYN_TICK_ENABLED; + } else { + if (dyn_tick_cfg->arch_disable) + dyn_tick_cfg->arch_disable(); + dyn_tick->state &= ~DYN_TICK_ENABLED; + } + write_sequnlock_irqrestore(&xtime_lock, flags); + + return count; +} + +static SYSDEV_ATTR(dyn_tick_state, 0644, show_dyn_tick_state, + set_dyn_tick_state); + +/* + * --------------------------------------------------------------------------- + * Init functions + * --------------------------------------------------------------------------- + */ + +static int __init dyn_tick_early_init(void) +{ + dyn_tick->state |= DYN_TICK_TIMER_INT; + return 0; +} + +subsys_initcall(dyn_tick_early_init); + +/* + * We need to initialize dynamic tick after calibrate delay + */ +static int __init dyn_tick_late_init(void) +{ + int ret = 0; + + if (dyn_tick_cfg == NULL || dyn_tick_cfg->arch_init == NULL || + !(dyn_tick->state & DYN_TICK_SUITABLE)) { + printk(KERN_ERR "dyn-tick: No suitable timer found\n"); + return -ENODEV; + } + + if (!dyntick_useapic) + dyn_tick->state &= ~DYN_TICK_USE_APIC; + + ret = dyn_tick_cfg->arch_init(); + if (ret != 0) { + printk(KERN_ERR "dyn-tick: Init failed\n"); + return -ENODEV; + } + + ret = sysdev_create_file(&device_timer, &attr_dyn_tick_state); + + if (ret == 0 && dyntick_autoenable) { + dyn_tick->state |= DYN_TICK_ENABLED; + printk(KERN_INFO "dyn-tick: Timer using dynamic tick\n"); + } else + printk(KERN_INFO "dyn-tick: Timer not enabled during boot\n"); + + return ret; +} + +late_initcall(dyn_tick_late_init); Index: linux-dev/arch/i386/kernel/timers/timer_pit.c =================================================================== --- linux-dev.orig/arch/i386/kernel/timers/timer_pit.c 2005-06-10 10:34:42.000000000 -0700 +++ linux-dev/arch/i386/kernel/timers/timer_pit.c 2005-06-10 10:36:12.000000000 -0700 @@ -149,6 +149,43 @@ return count; } +/* + * REVISIT: Looks like on P3 APIC timer keeps running if PIT mode + * is changed. On P4, changing PIT mode seems to kill + * APIC timer interrupts. Same thing with disabling PIT + * interrupt. + */ +void disable_pit_timer(void) +{ + extern spinlock_t i8253_lock; + unsigned long flags; + spin_lock_irqsave(&i8253_lock, flags); + outb_p(0x32, PIT_MODE); /* binary, mode 1, LSB/MSB, ch 0 */ + spin_unlock_irqrestore(&i8253_lock, flags); +} + +/* + * 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_timer(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); +} /* tsc timer_opts struct */ struct timer_opts timer_pit = {