Here is yet another updated version of the dynticks code. Changes: Rolled in the deadlock fix for 051218 Rolled in Dominik's latest C states code Added more helper functions to work with dynticks instead of accessing the dynticks struct directly: dyn_tick_skipping Returns if we are currently skipping ticks. dyn_tick_current_skip Returns the number of ticks we are currently skipping if we are skipping and dyn_tick_next_tick Returns the next scheduled dyn_tick if we are skipping ticks. Latest patch, split patches and timer utilties available here: http://ck.kolivas.org/patches/dyn-ticks/ Rolled up patch in this email. Cheers, Con --- Index: linux-2.6.15-rc6-dt/include/linux/dyn-tick.h =================================================================== --- /dev/null +++ linux-2.6.15-rc6-dt/include/linux/dyn-tick.h @@ -0,0 +1,107 @@ +/* + * linux/include/linux/dyn-tick.h + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[email protected]> + * Rewritten by Con Kolivas <[email protected]> + * + * 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 <linux/interrupt.h> + +#define DYN_TICK_SKIPPING (1 << 2) +#define DYN_TICK_ENABLED (1 << 1) +#define DYN_TICK_SUITABLE (1 << 0) + +/* Baseline tick rate of slowest timers in kernel - used for sanity checks */ +#define DYN_TICK_MAX_SKIP (HZ / 5) + +struct dyn_tick_timer { + spinlock_t lock; + + /* dyn_tick init */ + int (*arch_init) (void); + /* Enables dynamic tick */ + int (*arch_enable)(void); + /* Disables dynamic tick */ + int (*arch_disable)(void); + /* Reprograms the timer */ + void (*arch_reprogram)(unsigned long); + /* Function called when all cpus are idle */ + void (*arch_all_cpus_idle) (int); + + unsigned short state; /* Current state */ + unsigned int min_skip; /* Min number of ticks to skip */ + unsigned int max_skip; /* Max number of ticks to skip */ + unsigned long next_tick; /* Next tick we're skipping to */ + unsigned long skip; /* Ticks we're currently skipping */ +}; + +extern struct dyn_tick_timer *dyn_tick; +extern spinlock_t *dyn_tick_lock; + +extern void dyn_tick_register(struct dyn_tick_timer *new_timer); + +#ifdef CONFIG_NO_IDLE_HZ +DECLARE_PER_CPU(unsigned int, nohz_cpu); +extern int dyn_tick_enabled(void); +extern int dyn_tick_skipping(void); +extern int dyn_tick_current_skip(void); +extern unsigned long dyn_tick_next_tick(void); +extern void timer_dyn_reprogram(void); +extern void dyn_early_reprogram(unsigned int delta); +extern void set_dyn_tick_limits(unsigned int max_skip, unsigned int min_skip); + +#ifdef CONFIG_TIMER_INFO +extern int account_timer(unsigned long function, unsigned long data); +#else +static inline int account_timer(unsigned long function, unsigned long data) +{ + return 0; +} +#endif + +#else /* CONFIG_NO_IDLE_HZ */ +static inline int dyn_tick_enabled(void) +{ + return 0; +} + +static inline int dyn_tick_skipping(void) +{ + return 0; +} + +static inline int dyn_tick_current_skip(void) +{ + return 0; +} + +static inline unsigned long dyn_tick_next_tick(void) +{ + return 0; +} + +static inline void set_dyn_tick_limits(unsigned int max_skip, + unsigned int min_skip) +{ +} + +static inline void dyn_early_reprogram(unsigned int delta) +{ +} + +static inline int account_timer(unsigned long function, unsigned long data) +{ + return 0; +} +#endif /* CONFIG_NO_IDLE_HZ */ + +#endif /* _DYN_TICK_TIMER_H */ Index: linux-2.6.15-rc6-dt/include/linux/timer.h =================================================================== --- linux-2.6.15-rc6-dt.orig/include/linux/timer.h +++ linux-2.6.15-rc6-dt/include/linux/timer.h @@ -97,5 +97,6 @@ static inline void add_timer(struct time extern void init_timers(void); extern void run_local_timers(void); extern void it_real_fn(unsigned long); +extern void conditional_run_local_timers(void); #endif Index: linux-2.6.15-rc6-dt/kernel/dyn-tick.c =================================================================== --- /dev/null +++ linux-2.6.15-rc6-dt/kernel/dyn-tick.c @@ -0,0 +1,305 @@ +/* + * linux/kernel/dyn-tick.c + * + * Generic dynamic tick timer support + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[email protected]> + * Rewritten by Con Kolivas <[email protected]> + * + * 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 <linux/version.h> +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/sysdev.h> +#include <linux/interrupt.h> +#include <linux/cpumask.h> +#include <linux/pm.h> +#include <linux/dyn-tick.h> +#include <linux/rcupdate.h> +#include <asm/dyn-tick.h> + +#define DYN_TICK_VERSION "051219" + +inline int dyn_tick_enabled(void) +{ + return !!(dyn_tick->state & DYN_TICK_ENABLED); +} + +EXPORT_SYMBOL(dyn_tick_enabled); + +/* + * Returns if we are currently skipping ticks. + */ +inline int dyn_tick_skipping(void) +{ + return (dyn_tick->next_tick > jiffies); +} + +EXPORT_SYMBOL(dyn_tick_skipping); + +/* + * Returns the number of ticks we are currently skipping if we are skipping + */ +int dyn_tick_current_skip(void) +{ + int ret = 0; + + if (dyn_tick_skipping()) + ret = dyn_tick->skip; + return ret; +} + +EXPORT_SYMBOL(dyn_tick_current_skip); + +/* + * Returns the next scheduled dyn_tick if we are skipping ticks. + */ +unsigned long dyn_tick_next_tick(void) +{ + unsigned long next = 0; + + if (dyn_tick_skipping()) + next = dyn_tick->next_tick; + return next; +} + +EXPORT_SYMBOL(dyn_tick_next_tick); + +static inline int dyn_tick_suitable(void) +{ + return !!(dyn_tick->state & DYN_TICK_SUITABLE); +} + +/* + * do_dyn_reprogram does the actual reprogramming. We should have already + * checked that the tick chosen is suitable, xtime_lock and dyn_tick->lock + * must be held, and interrupts disabled. + */ +static void do_dyn_reprogram(unsigned int delta) +{ + dyn_tick->next_tick = jiffies + delta; + dyn_tick->skip = delta; + dyn_tick->arch_reprogram(dyn_tick->next_tick); + /* We have to update the idle_timestamp */ + __get_cpu_var(irq_stat).idle_timestamp = dyn_tick->next_tick; +} + +/* + * Per cpu nohz information. This seems redundant but querying this first + * elsewhere can avoid the need to query nohz_cpu_mask and the subsequent + * cache thrashing. + */ +DEFINE_PER_CPU(unsigned int, nohz_cpu); + +/* + * We will be doing this only from the idle loop so preemption is already + * disabled allowing us to use the direct __get_cpu_var + */ +static inline void set_nohz_cpu(int cpu) +{ + if (__get_cpu_var(nohz_cpu)) + return; + __get_cpu_var(nohz_cpu) = 1; + cpu_set(cpu, nohz_cpu_mask); +} + +/* + * Arch independent code needed to reprogram next timer interrupt. + * Gets called, with IRQs disabled, from cpu_idle() before entering idle loop + * If we are to acquire the xtime_lock we must acquire it before + * dyn_tick->lock + */ +void timer_dyn_reprogram(void) +{ + int cpu; + unsigned int delta; + + if (!dyn_tick_enabled()) + return; + + cpu = smp_processor_id(); + if (rcu_pending(cpu) || local_softirq_pending()) + return; + + write_seqlock(&xtime_lock); + delta = next_timer_interrupt() - jiffies; + spin_lock(&dyn_tick->lock); + if (delta > dyn_tick->max_skip) + delta = dyn_tick->max_skip; + if (delta > dyn_tick->min_skip) { + int idle_time = 0; + + if (dyn_tick->next_tick == jiffies) + idle_time = dyn_tick->skip; + do_dyn_reprogram(delta); + set_nohz_cpu(cpu); + if (cpus_equal(nohz_cpu_mask, cpu_online_map)) + dyn_tick->arch_all_cpus_idle(idle_time); + } + spin_unlock(&dyn_tick->lock); + write_sequnlock(&xtime_lock); +} + +/* + * dyn_early_reprogram is used to reprogram an earlier tick than is currently + * set by timer_dyn_reprogram. + * dyn_early_reprogram allows other code such as the acpi idle code to + * program an earlier tick than the one already chosen by timer_dyn_reprogram. + * It only reprograms it if the tick is earlier than the next one planned. + */ +void dyn_early_reprogram(unsigned int delta) +{ + unsigned long flags, tick = jiffies + delta; + + if (tick >= dyn_tick->next_tick && dyn_tick->next_tick > jiffies) + return; + + write_seqlock_irqsave(&xtime_lock, flags); + spin_lock(&dyn_tick->lock); + do_dyn_reprogram(delta); + spin_unlock(&dyn_tick->lock); + write_sequnlock_irqrestore(&xtime_lock, flags); +} + +EXPORT_SYMBOL(dyn_early_reprogram); + +/* + * Set limits on minimum and maximum number of ticks to skip. The minimum + * may want to be set by other code but is at least one tick. + */ +void set_dyn_tick_limits(unsigned int max_skip, unsigned int min_skip) +{ + if (max_skip > DYN_TICK_MAX_SKIP) + max_skip = DYN_TICK_MAX_SKIP; + if (!dyn_tick->max_skip || max_skip < dyn_tick->max_skip) + dyn_tick->max_skip = max_skip; + if (min_skip < 1) + min_skip = 1; + if (min_skip > dyn_tick->min_skip) + dyn_tick->min_skip = min_skip; +} + +void __init dyn_tick_register(struct dyn_tick_timer *arch_timer) +{ + dyn_tick = arch_timer; +} + +/* Default to enabled */ +static int __initdata dyntick_autoenable = 1; + +/* + * Command line options. + * + * dyntick=[enable|disable] + */ +static int __init dyntick_setup(char *options) +{ + if (!options) + return 0; + + if (!strncmp(options, "enable", 5)) + dyntick_autoenable = 1; + if (!strncmp(options, "disable", 6)) + dyntick_autoenable = 0; + + return 0; +} + +__setup("dyntick=", dyntick_setup); + +/* + * Sysfs interface. + * + * Usually situated at: + * /sys/devices/system/timer/timer0/dyn_tick + */ +extern struct sys_device device_timer; + +static ssize_t timer_show_dyn_tick(struct sys_device *dev, char *buf) +{ + return sprintf(buf, "%i\n", dyn_tick_enabled()); +} + +static ssize_t timer_set_dyn_tick(struct sys_device *dev, const char *buf, + size_t count) +{ + unsigned long flags; + unsigned int enable = simple_strtoul(buf, NULL, 2); + int ret = -ENODEV; + + write_seqlock_irqsave(&xtime_lock, flags); + if (enable) { + ret = dyn_tick->arch_enable(); + if (ret == 0) { + spin_lock(&dyn_tick->lock); + dyn_tick->state |= DYN_TICK_ENABLED; + spin_unlock(&dyn_tick->lock); + printk(KERN_INFO + "dyn-tick: Enabling dynamic tick timer \n"); + } + } else { + ret = dyn_tick->arch_disable(); + if (ret == 0) { + spin_lock(&dyn_tick->lock); + dyn_tick->state &= ~DYN_TICK_ENABLED; + spin_unlock(&dyn_tick->lock); + printk(KERN_INFO + "dyn-tick: Disabling dynamic tick timer \n"); + } + } + write_sequnlock_irqrestore(&xtime_lock, flags); + + return count; +} + +static SYSDEV_ATTR(dyn_tick, 0644, timer_show_dyn_tick, timer_set_dyn_tick); + +static int __init init_dyn_tick_sysfs(void) +{ + int ret = sysdev_create_file(&device_timer, &attr_dyn_tick); + + return ret; +} + +device_initcall(init_dyn_tick_sysfs); + +/* + * Init functions + * + * We need to initialise dynamic tick after calibrate delay + */ +static int __init dyn_tick_late_init(void) +{ + int ret; + + if (dyn_tick == NULL || dyn_tick->arch_init == NULL || + !dyn_tick_suitable()) { + printk(KERN_ERR "dyn-tick: No suitable timer found\n"); + return -ENODEV; + } + + if ((ret = dyn_tick->arch_init())) { + printk(KERN_ERR "dyn-tick: Init failed\n"); + return -ENODEV; + } + + if (!ret && dyntick_autoenable) { + dyn_tick->state |= DYN_TICK_ENABLED; + printk(KERN_INFO "dyn-tick: Enabling dynamic tick timer v%s\n", + DYN_TICK_VERSION); + } else + printk(KERN_INFO "dyn-tick: Dynamic tick timer v%s disabled\n", + DYN_TICK_VERSION); + + return ret; +} + +late_initcall(dyn_tick_late_init); Index: linux-2.6.15-rc6-dt/kernel/Makefile =================================================================== --- linux-2.6.15-rc6-dt.orig/kernel/Makefile +++ linux-2.6.15-rc6-dt/kernel/Makefile @@ -32,6 +32,8 @@ obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o +obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick.o +obj-$(CONFIG_TIMER_INFO) += timer_top.o ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y) # According to Alan Modra <[email protected]>, the -fno-omit-frame-pointer is Index: linux-2.6.15-rc6-dt/kernel/timer.c =================================================================== --- linux-2.6.15-rc6-dt.orig/kernel/timer.c +++ linux-2.6.15-rc6-dt/kernel/timer.c @@ -33,6 +33,7 @@ #include <linux/posix-timers.h> #include <linux/cpu.h> #include <linux/syscalls.h> +#include <linux/dyn-tick.h> #include <asm/uaccess.h> #include <asm/unistd.h> @@ -540,6 +541,8 @@ found: expires = nte->expires; } } + account_timer((unsigned long)nte->function, nte->data); + spin_unlock(&base->t_base.lock); return expires; } @@ -869,6 +872,13 @@ void run_local_timers(void) raise_softirq(TIMER_SOFTIRQ); } +void conditional_run_local_timers(void) +{ + tvec_base_t *base = &__get_cpu_var(tvec_bases); + + if (base->timer_jiffies != jiffies) + run_local_timers(); +} /* * Called by the timer interrupt. xtime_lock must already be taken * by the timer IRQ! Index: linux-2.6.15-rc6-dt/drivers/acpi/Kconfig =================================================================== --- linux-2.6.15-rc6-dt.orig/drivers/acpi/Kconfig +++ linux-2.6.15-rc6-dt/drivers/acpi/Kconfig @@ -301,6 +301,8 @@ config X86_PM_TIMER voltage scaling, unlike the commonly used Time Stamp Counter (TSC) timing source. + This timer is selected by dyntick (NO_IDLE_HZ). + So, if you see messages like 'Losing too many ticks!' in the kernel logs, and/or you are using this on a notebook which does not yet have an HPET, you should say "Y" here. Index: linux-2.6.15-rc6-dt/arch/i386/defconfig =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/defconfig +++ linux-2.6.15-rc6-dt/arch/i386/defconfig @@ -91,6 +91,7 @@ CONFIG_X86_INTEL_USERCOPY=y CONFIG_X86_USE_PPRO_CHECKSUM=y # CONFIG_HPET_TIMER is not set # CONFIG_HPET_EMULATE_RTC is not set +# CONFIG_NO_IDLE_HZ is not set CONFIG_SMP=y CONFIG_NR_CPUS=8 CONFIG_SCHED_SMT=y Index: linux-2.6.15-rc6-dt/arch/i386/Kconfig =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/Kconfig +++ linux-2.6.15-rc6-dt/arch/i386/Kconfig @@ -173,6 +173,26 @@ config HPET_EMULATE_RTC depends on HPET_TIMER && RTC=y default y +config NO_IDLE_HZ + bool "Dynamic Tick Timer - Skip timer ticks during idle" + depends on EXPERIMENTAL + select X86_PM_TIMER + 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 the only supported timer is ACPI PM + timer. + + Note that you can disable dynamic tick timer either by + passing dyntick=disable command line option, or via sysfs: + + # echo 0 > /sys/devices/system/timer/timer0/dyn_tick + + Most users wishing to lower their power usage while retaining + low latencies will most likely want to say Y here in combination + with a high HZ value (eg 1000). + config SMP bool "Symmetric multi-processing support" ---help--- Index: linux-2.6.15-rc6-dt/arch/i386/kernel/apic.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/apic.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/apic.c @@ -26,6 +26,7 @@ #include <linux/kernel_stat.h> #include <linux/sysdev.h> #include <linux/cpu.h> +#include <linux/dyn-tick.h> #include <asm/atomic.h> #include <asm/smp.h> @@ -35,6 +36,7 @@ #include <asm/arch_hooks.h> #include <asm/hpet.h> #include <asm/i8253.h> +#include <asm/dyn-tick.h> #include <mach_apic.h> @@ -932,6 +934,9 @@ void (*wait_timer_tick)(void) __devinitd #define APIC_DIVISOR 16 +static u32 apic_timer_val __read_mostly; +#define APIC_TIMER_VAL ((apic_timer_val) / (HZ)) + static void __setup_APIC_LVTT(unsigned int clocks) { unsigned int lvtt_value, tmp_value, ver; @@ -950,7 +955,9 @@ static void __setup_APIC_LVTT(unsigned i & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE)) | APIC_TDR_DIV_16); - apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR); + apic_timer_val = clocks * HZ / APIC_DIVISOR; + + apic_write_around(APIC_TMICT, APIC_TIMER_VAL); } static void __devinit setup_APIC_timer(unsigned int clocks) @@ -969,6 +976,17 @@ static void __devinit setup_APIC_timer(u local_irq_restore(flags); } +/* Used by NO_IDLE_HZ to skip ticks on idle CPUs */ +void reprogram_apic_timer(unsigned long count) +{ + unsigned long flags; + + count = count * apic_timer_val / HZ; + local_irq_save(flags); + apic_write_around(APIC_TMICT, count); + local_irq_restore(flags); +} + /* * In this function we calibrate APIC bus clocks to the external * timer. Unfortunately we cannot use jiffies and the timer irq @@ -1064,6 +1082,10 @@ void __init setup_boot_APIC_clock(void) */ setup_APIC_timer(calibration_result); + if (setup_dyn_tick_use_apic(calibration_result)) + set_dyn_tick_limits((0xFFFFFFFF / calibration_result) * + APIC_DIVISOR, 0); + local_irq_restore(flags); } @@ -1202,6 +1224,9 @@ fastcall void smp_apic_timer_interrupt(s * interrupt lock, which is the WrongThing (tm) to do. */ irq_enter(); + + dyn_tick_interrupt(regs); + smp_local_timer_interrupt(regs); irq_exit(); } @@ -1214,6 +1239,9 @@ fastcall void smp_spurious_interrupt(str unsigned long v; irq_enter(); + + dyn_tick_interrupt(regs); + /* * Check if this really is a spurious interrupt and ACK it * if it is a vectored one. Just in case... @@ -1238,6 +1266,9 @@ fastcall void smp_error_interrupt(struct unsigned long v, v1; irq_enter(); + + dyn_tick_interrupt(regs); + /* First tickle the hardware, only then report what went on. -- REW */ v = apic_read(APIC_ESR); apic_write(APIC_ESR, 0); Index: linux-2.6.15-rc6-dt/arch/i386/kernel/dyn-tick.c =================================================================== --- /dev/null +++ linux-2.6.15-rc6-dt/arch/i386/kernel/dyn-tick.c @@ -0,0 +1,178 @@ +/* + * linux/arch/i386/kernel/dyn-tick.c + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[email protected]> + * Rewritten by Con Kolivas <[email protected]> + * + * 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 <linux/version.h> +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/dyn-tick.h> +#include <linux/timer.h> +#include <linux/irq.h> +#include <linux/kernel_stat.h> +#include <asm/apic.h> +#include <asm/dyn-tick.h> + +/* We only skip 200ms maximum so no need to disable the NMI Watchdog */ +static void apic_reprogram(unsigned long jif_next) +{ + reprogram_apic_timer(jif_next - jiffies); +} + +static void pit_reprogram(unsigned long jif_next) +{ + reprogram_pit_timer(jif_next - jiffies); +} + +static void arch_all_cpus_idle(int __unused) +{ + if (dyntick_using_lapic()) + disable_pit_timer(); +} + +static int arch_enable(void) +{ + return 0; +} + +static int arch_disable(void) +{ + return 0; +} + +static struct dyn_tick_timer arch_dyn_tick = { + .lock = SPIN_LOCK_UNLOCKED, + .arch_reprogram = &pit_reprogram, + .arch_all_cpus_idle = &arch_all_cpus_idle, + .arch_enable = &arch_enable, + .arch_disable = &arch_disable, +}; + +struct dyn_tick_timer *dyn_tick = &arch_dyn_tick; + +static inline void set_pit_limits(void) +{ + set_dyn_tick_limits(0xffff / LATCH, 0); +} + +int __init dyn_tick_arch_init(void) +{ + if (!dyntick_using_lapic()) + set_pit_limits(); + + printk(KERN_INFO "dyn-tick: Maximum ticks to skip limited to %i\n", + dyn_tick->max_skip); + + return 0; +} + +static int __init dyn_tick_init(void) +{ + dyn_tick->arch_init = dyn_tick_arch_init; + dyn_tick_register(&arch_dyn_tick); + + return 0; +} + +arch_initcall(dyn_tick_init); + +static void dyntick_disable_lapic(void) +{ + dyn_tick->state &= ~DYN_TICK_APICABLE; + printk(KERN_INFO "dyn-tick: Cannot use this local APIC with dynticks\n"); + set_pit_limits(); + dyn_tick->arch_reprogram = &pit_reprogram; +} + +/* Functions that need blank prototypes for !CONFIG_NO_IDLE_HZ below here */ +int __init setup_dyn_tick_use_apic(unsigned int calibration_result) +{ + if (calibration_result) { + dyn_tick->arch_reprogram = &apic_reprogram; + dyn_tick->state |= DYN_TICK_APICABLE; + return 1; + } + dyntick_disable_lapic(); + return 0; +} + +/* + * The apparently redundant per_cpu nohz_cpu value is tested in this + * function and this is where we can avoid the cache thrashing of testing + * nohz_cpu_mask. Preemption is already disabled when this is called. + */ +static inline int test_nohz_cpu(void) +{ + return __get_cpu_var(nohz_cpu); +} + +static inline void clear_nohz_cpu(int cpu) +{ + __get_cpu_var(nohz_cpu) = 0; + cpu_clear(cpu, nohz_cpu_mask); +} + +static void do_dyn_tick_interrupt(struct pt_regs *regs) +{ + int cpu = smp_processor_id(); + + write_seqlock(&xtime_lock); + spin_lock(&dyn_tick->lock); + if (cpus_equal(nohz_cpu_mask, cpu_online_map)) { + /* All were sleeping, recover jiffies */ + int lost = cur_timer->mark_offset(); + + if (lost && in_irq()) + do_timer(regs); + if (dyntick_using_lapic()) { + enable_pit_timer(); + if (unlikely(lost > DYN_TICK_MAX_SKIP + 1)) + dyntick_disable_lapic(); + } + kstat_cpu(cpu).cpustat.idle += (lost - 1); + } + clear_nohz_cpu(cpu); + spin_unlock(&dyn_tick->lock); + write_sequnlock(&xtime_lock); + + /* Make sure we don't miss the next timer tick */ + dyn_early_reprogram(1); + + conditional_run_local_timers(); +} + +inline void dyn_tick_interrupt(struct pt_regs *regs) +{ + if (!test_nohz_cpu()) + return; + do_dyn_tick_interrupt(regs); +} + +void __init dyn_tick_time_init(struct timer_opts *cur_timer) +{ + if (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); +} + +inline void idle_reprogram_timer(void) +{ + local_irq_disable(); + if (!need_resched()) + timer_dyn_reprogram(); + local_irq_enable(); +} Index: linux-2.6.15-rc6-dt/arch/i386/kernel/io_apic.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/io_apic.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/io_apic.c @@ -32,6 +32,7 @@ #include <linux/acpi.h> #include <linux/module.h> #include <linux/sysdev.h> +#include <linux/dyn-tick.h> #include <asm/io.h> #include <asm/smp.h> @@ -1179,6 +1180,7 @@ next: static struct hw_interrupt_type ioapic_level_type; static struct hw_interrupt_type ioapic_edge_type; +static struct hw_interrupt_type ioapic_edge_type_irq0; #define IOAPIC_AUTO -1 #define IOAPIC_EDGE 0 @@ -1190,15 +1192,19 @@ static inline void ioapic_register_intr( if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) || trigger == IOAPIC_LEVEL) irq_desc[vector].handler = &ioapic_level_type; - else + else if (vector) irq_desc[vector].handler = &ioapic_edge_type; + else + irq_desc[vector].handler = &ioapic_edge_type_irq0; set_intr_gate(vector, interrupt[vector]); } else { if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) || trigger == IOAPIC_LEVEL) irq_desc[irq].handler = &ioapic_level_type; - else + else if (irq) irq_desc[irq].handler = &ioapic_edge_type; + else + irq_desc[irq].handler = &ioapic_edge_type_irq0; set_intr_gate(vector, interrupt[irq]); } } @@ -1311,7 +1317,7 @@ static void __init setup_ExtINT_IRQ0_pin * The timer IRQ doesn't have to know that behind the * scene we have a 8259A-master in AEOI mode ... */ - irq_desc[0].handler = &ioapic_edge_type; + irq_desc[0].handler = &ioapic_edge_type_irq0; /* * Add it to the IO-APIC irq-routing table: @@ -2088,6 +2094,20 @@ static struct hw_interrupt_type ioapic_l #endif }; +/* Needed to disable PIT interrupts when all CPUs sleep */ +static struct hw_interrupt_type ioapic_edge_type_irq0 __read_mostly = { + .typename = "IO-APIC-edge-irq0", + .startup = startup_edge_ioapic, + .shutdown = shutdown_edge_ioapic, + .enable = unmask_IO_APIC_irq, + .disable = mask_IO_APIC_irq, + .ack = ack_edge_ioapic, + .end = end_edge_ioapic, +#ifdef CONFIG_SMP + .set_affinity = set_ioapic_affinity, +#endif +}; + static inline void init_IO_APIC_traps(void) { int irq; Index: linux-2.6.15-rc6-dt/arch/i386/kernel/irq.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/irq.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/irq.c @@ -18,6 +18,8 @@ #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/delay.h> +#include <linux/dyn-tick.h> +#include <asm/dyn-tick.h> DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_maxaligned_in_smp; EXPORT_PER_CPU_SYMBOL(irq_stat); @@ -76,6 +78,8 @@ fastcall unsigned int do_IRQ(struct pt_r } #endif + dyn_tick_interrupt(regs); + #ifdef CONFIG_4KSTACKS curctx = (union irq_ctx *) current_thread_info(); Index: linux-2.6.15-rc6-dt/arch/i386/kernel/Makefile =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/Makefile +++ linux-2.6.15-rc6-dt/arch/i386/kernel/Makefile @@ -32,6 +32,7 @@ obj-$(CONFIG_MODULES) += module.o 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-2.6.15-rc6-dt/arch/i386/kernel/process.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/process.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/process.c @@ -39,6 +39,7 @@ #include <linux/ptrace.h> #include <linux/random.h> #include <linux/kprobes.h> +#include <linux/dyn-tick.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -56,6 +57,7 @@ #include <asm/tlbflush.h> #include <asm/cpu.h> +#include <asm/dyn-tick.h> asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); @@ -194,6 +196,8 @@ void cpu_idle(void) play_dead(); __get_cpu_var(irq_stat).idle_timestamp = jiffies; + idle_reprogram_timer(); + idle(); } preempt_enable_no_resched(); Index: linux-2.6.15-rc6-dt/arch/i386/kernel/smp.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/smp.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/smp.c @@ -20,9 +20,11 @@ #include <linux/interrupt.h> #include <linux/cpu.h> #include <linux/module.h> +#include <linux/dyn-tick.h> #include <asm/mtrr.h> #include <asm/tlbflush.h> +#include <asm/dyn-tick.h> #include <mach_apic.h> /* @@ -313,6 +315,8 @@ fastcall void smp_invalidate_interrupt(s { unsigned long cpu; + dyn_tick_interrupt(regs); + cpu = get_cpu(); if (!cpu_isset(cpu, flush_cpumask)) @@ -600,6 +604,8 @@ void smp_send_stop(void) fastcall void smp_reschedule_interrupt(struct pt_regs *regs) { ack_APIC_irq(); + + dyn_tick_interrupt(regs); } fastcall void smp_call_function_interrupt(struct pt_regs *regs) @@ -609,6 +615,9 @@ fastcall void smp_call_function_interrup int wait = call_data->wait; ack_APIC_irq(); + + dyn_tick_interrupt(regs); + /* * Notify initiating CPU that I've grabbed the data and am * about to execute the function Index: linux-2.6.15-rc6-dt/arch/i386/kernel/time.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/time.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/time.c @@ -46,6 +46,7 @@ #include <linux/bcd.h> #include <linux/efi.h> #include <linux/mca.h> +#include <linux/dyn-tick.h> #include <asm/io.h> #include <asm/smp.h> @@ -56,6 +57,7 @@ #include <asm/uaccess.h> #include <asm/processor.h> #include <asm/timer.h> +#include <asm/dyn-tick.h> #include "mach_time.h" @@ -245,7 +247,7 @@ EXPORT_SYMBOL(profile_pc); * timer_interrupt() needs to keep up the real-time clock, * as well as call the "do_timer()" routine every clocktick */ -static inline void do_timer_interrupt(int irq, struct pt_regs *regs) +static inline void do_timer_interrupt(int irq, struct pt_regs *regs, int lost) { #ifdef CONFIG_X86_IO_APIC if (timer_ack) { @@ -263,7 +265,8 @@ static inline void do_timer_interrupt(in } #endif - do_timer_interrupt_hook(regs); + if (!dyn_tick_enabled() || lost) + do_timer_interrupt_hook(regs); if (MCA_bus) { @@ -288,6 +291,8 @@ static inline void do_timer_interrupt(in */ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) { + int lost; + /* * Here we are in the timer irq handler. We just have irqs locally * disabled but we don't know if the timer_bh is running on the other @@ -297,9 +302,9 @@ irqreturn_t timer_interrupt(int irq, voi */ write_seqlock(&xtime_lock); - cur_timer->mark_offset(); - - do_timer_interrupt(irq, regs); + lost = cur_timer->mark_offset(); + + do_timer_interrupt(irq, regs, lost); write_sequnlock(&xtime_lock); return IRQ_HANDLED; @@ -425,7 +430,7 @@ static struct sysdev_class timer_sysclas /* 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, }; @@ -481,5 +486,7 @@ void __init time_init(void) cur_timer = select_timer(); printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name); + dyn_tick_time_init(cur_timer); + time_init_hook(); } Index: linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_pit.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/timers/timer_pit.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_pit.c @@ -32,9 +32,10 @@ static int __init init_pit(char* overrid return 0; } -static void mark_offset_pit(void) +static int mark_offset_pit(void) { /* nothing needed */ + return 1; } static unsigned long long monotonic_clock_pit(void) @@ -148,6 +149,38 @@ static unsigned long get_offset_pit(void return count; } +void disable_pit_timer(void) +{ + irq_desc[0].handler->disable(0); +} + +void enable_pit_timer(void) +{ + irq_desc[0].handler->enable(0); +} + +/* + * 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(unsigned long 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 = { Index: linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_pm.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/timers/timer_pm.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_pm.c @@ -15,6 +15,7 @@ #include <linux/module.h> #include <linux/device.h> #include <linux/init.h> +#include <linux/dyn-tick.h> #include <asm/types.h> #include <asm/timer.h> #include <asm/smp.h> @@ -28,7 +29,7 @@ #define PMTMR_TICKS_PER_SEC 3579545 #define PMTMR_EXPECTED_RATE \ ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10)) - +#define PMTMR_TICKS_PER_JIFFY (PMTMR_EXPECTED_RATE / (CALIBRATE_LATCH/LATCH)) /* The I/O port the PMTMR resides at. * The location is detected during setup_arch(), @@ -127,7 +128,13 @@ pm_good: if (verify_pmtmr_rate() != 0) return -ENODEV; + printk("Using %u PM timer ticks per jiffy \n", PMTMR_TICKS_PER_JIFFY); + + offset_tick = read_pmtmr(); + setup_pit_timer(); + init_cpu_khz(); + set_dyn_tick_limits(((0xFFFFFF / 1000000) * 286 * HZ) >> 10, 0); return 0; } @@ -148,10 +155,9 @@ static inline u32 cyc2us(u32 cycles) * this gets called during each timer interrupt * - Called while holding the writer xtime_lock */ -static void mark_offset_pmtmr(void) +static int mark_offset_pmtmr(void) { u32 lost, delta, last_offset; - static int first_run = 1; last_offset = offset_tick; write_seqlock(&monotonic_lock); @@ -161,29 +167,20 @@ static void mark_offset_pmtmr(void) /* calculate tick interval */ delta = (offset_tick - last_offset) & ACPI_PM_MASK; - /* convert to usecs */ - delta = cyc2us(delta); - /* update the monotonic base value */ - monotonic_base += delta * NSEC_PER_USEC; + monotonic_base += cyc2us(delta) * NSEC_PER_USEC; write_sequnlock(&monotonic_lock); /* convert to ticks */ delta += offset_delay; - lost = delta / (USEC_PER_SEC / HZ); - offset_delay = delta % (USEC_PER_SEC / HZ); - + lost = delta / PMTMR_TICKS_PER_JIFFY; + offset_delay = delta % PMTMR_TICKS_PER_JIFFY; /* compensate for lost ticks */ if (lost >= 2) jiffies_64 += lost - 1; - /* don't calculate delay for first run, - or if we've got less then a tick */ - if (first_run || (lost < 1)) { - first_run = 0; - offset_delay = 0; - } + return lost; } static int pmtmr_resume(void) @@ -192,6 +189,7 @@ static int pmtmr_resume(void) /* Assume this is the last mark offset time */ offset_tick = read_pmtmr(); write_sequnlock(&monotonic_lock); + offset_delay = 0; return 0; } @@ -243,7 +241,7 @@ static unsigned long get_offset_pmtmr(vo now = read_pmtmr(); delta = (now - offset)&ACPI_PM_MASK; - return (unsigned long) offset_delay + cyc2us(delta); + return (unsigned long) cyc2us(delta + offset_delay); } Index: linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_tsc.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/timers/timer_tsc.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_tsc.c @@ -14,6 +14,7 @@ #include <linux/cpufreq.h> #include <linux/string.h> #include <linux/jiffies.h> +#include <linux/dyn-tick.h> #include <asm/timer.h> #include <asm/io.h> @@ -32,8 +33,6 @@ static unsigned long hpet_last; static struct timer_opts timer_tsc; #endif -static inline void cpufreq_delayed_get(void); - int tsc_disable __devinitdata = 0; static int use_tsc; @@ -171,11 +170,21 @@ static void delay_tsc(unsigned long loop } while ((now-bclock) < loops); } +/* update the monotonic base value */ +static inline void update_monotonic_base(unsigned long long last_offset) +{ + unsigned long long this_offset; + + this_offset = ((unsigned long long)last_tsc_high << 32) | last_tsc_low; + monotonic_base += cycles_2_ns(this_offset - last_offset); +} + #ifdef CONFIG_HPET_TIMER -static void mark_offset_tsc_hpet(void) +static int mark_offset_tsc_hpet(void) { - unsigned long long this_offset, last_offset; + unsigned long long last_offset; unsigned long offset, temp, hpet_current; + int lost_ticks = 0; write_seqlock(&monotonic_lock); last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low; @@ -197,14 +206,12 @@ static void mark_offset_tsc_hpet(void) /* lost tick compensation */ offset = hpet_readl(HPET_T0_CMP) - hpet_tick; if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) { - int lost_ticks = (offset - hpet_last) / hpet_tick; + lost_ticks = (offset - hpet_last) / hpet_tick; jiffies_64 += lost_ticks; } hpet_last = hpet_current; - /* 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); + update_monotonic_base(last_offset); write_sequnlock(&monotonic_lock); /* calculate delay_at_last_interrupt */ @@ -218,6 +225,8 @@ static void mark_offset_tsc_hpet(void) delay_at_last_interrupt = hpet_current - offset; ASM_MUL64_REG(temp, delay_at_last_interrupt, hpet_usec_quotient, delay_at_last_interrupt); + + return lost_ticks; } #endif @@ -242,7 +251,7 @@ static void handle_cpufreq_delayed_get(v * to verify the CPU frequency the timing core thinks the CPU is running * at is still correct. */ -static inline void cpufreq_delayed_get(void) +void cpufreq_delayed_get(void) { if (cpufreq_init && !cpufreq_delayed_issched) { cpufreq_delayed_issched = 1; @@ -321,7 +330,7 @@ static int __init cpufreq_tsc(void) core_initcall(cpufreq_tsc); #else /* CONFIG_CPU_FREQ */ -static inline void cpufreq_delayed_get(void) { return; } +void cpufreq_delayed_get(void) { return; } #endif int recalibrate_cpu_khz(void) @@ -344,15 +353,14 @@ int recalibrate_cpu_khz(void) } EXPORT_SYMBOL(recalibrate_cpu_khz); -static void mark_offset_tsc(void) +static int mark_offset_tsc(void) { unsigned long lost,delay; unsigned long delta = last_tsc_low; int count; int countmp; static int count1 = 0; - unsigned long long this_offset, last_offset; - static int lost_count = 0; + unsigned long long last_offset; write_seqlock(&monotonic_lock); last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low; @@ -419,29 +427,9 @@ static void mark_offset_tsc(void) delta += delay_at_last_interrupt; lost = delta/(1000000/HZ); delay = delta%(1000000/HZ); - if (lost >= 2) { - jiffies_64 += lost-1; + tsc_sanity_check(lost); - /* sanity check to ensure we're not always losing ticks */ - if (lost_count++ > 100) { - printk(KERN_WARNING "Losing too many ticks!\n"); - printk(KERN_WARNING "TSC cannot be used as a timesource. \n"); - printk(KERN_WARNING "Possible reasons for this are:\n"); - printk(KERN_WARNING " You're running with Speedstep,\n"); - printk(KERN_WARNING " You don't have DMA enabled for your hard disk (see hdparm),\n"); - printk(KERN_WARNING " Incorrect TSC synchronization on an SMP system (see dmesg).\n"); - printk(KERN_WARNING "Falling back to a sane timesource now.\n"); - - clock_fallback(); - } - /* ... but give the TSC a fair chance */ - if (lost_count > 25) - cpufreq_delayed_get(); - } else - lost_count = 0; - /* 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); + update_monotonic_base(last_offset); write_sequnlock(&monotonic_lock); /* calculate delay_at_last_interrupt */ @@ -454,6 +442,8 @@ static void mark_offset_tsc(void) */ if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ)) jiffies_64++; + + return lost; } static int __init init_tsc(char* override) @@ -542,6 +532,8 @@ static int __init init_tsc(char* overrid cpu_khz / 1000, cpu_khz % 1000); } set_cyc2ns_scale(cpu_khz); + set_dyn_tick_limits((0xFFFFFFFF / (cpu_khz * 1000)) * + HZ, 0); return 0; } } Index: linux-2.6.15-rc6-dt/include/asm-i386/apic.h =================================================================== --- linux-2.6.15-rc6-dt.orig/include/asm-i386/apic.h +++ linux-2.6.15-rc6-dt/include/asm-i386/apic.h @@ -121,6 +121,7 @@ extern void nmi_watchdog_tick (struct pt extern int APIC_init_uniprocessor (void); extern void disable_APIC_timer(void); extern void enable_APIC_timer(void); +extern void reprogram_apic_timer(unsigned long count); extern void enable_NMI_through_LVT0 (void * dummy); @@ -134,6 +135,7 @@ extern int disable_timer_pin_1; #else /* !CONFIG_X86_LOCAL_APIC */ static inline void lapic_shutdown(void) { } +static inline void reprogram_apic_timer(unsigned long count) { } #endif /* !CONFIG_X86_LOCAL_APIC */ Index: linux-2.6.15-rc6-dt/include/asm-i386/dyn-tick.h =================================================================== --- /dev/null +++ linux-2.6.15-rc6-dt/include/asm-i386/dyn-tick.h @@ -0,0 +1,65 @@ +/* + * linux/include/asm-i386/dyn-tick.h + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[email protected]> + * Rewritten by Con Kolivas <[email protected]> + * + * 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_ + +#include <asm/apic.h> +#include <asm/timer.h> + +#ifdef CONFIG_NO_IDLE_HZ +extern void idle_reprogram_timer(void); +extern void dyn_tick_interrupt(struct pt_regs *regs); +extern int __init setup_dyn_tick_use_apic(unsigned int calibration_result); +extern void __init dyn_tick_time_init(struct timer_opts *cur_timer); + +/* + * Needs to be different to the arch independant values specified in + * include/linux/dyn-tick.h to share the dyn_tick_timer.state struct + * member. + */ +#define DYN_TICK_APICABLE (1 << 3) + +#if (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC)) +static inline int dyntick_using_lapic(void) +{ + return (dyn_tick->state & DYN_TICK_APICABLE); +} + +#else /* (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC)) */ +static inline int dyntick_using_lapic(void) +{ + return 0; +} +#endif /* (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC)) */ + +#else /* CONFIG_NO_IDLE_HZ */ +static inline void idle_reprogram_timer(void) +{ +} + +static inline void dyn_tick_interrupt(struct pt_regs *regs) +{ +} + +static inline int setup_dyn_tick_use_apic(unsigned int calibration_result) +{ + return 0; +} + +static inline void dyn_tick_time_init(struct timer_opts *cur_timer) +{ +} +#endif /* CONFIG_NO_IDLE_HZ */ + +#endif /* _ASM_I386_DYN_TICK_H_ */ Index: linux-2.6.15-rc6-dt/include/asm-i386/timer.h =================================================================== --- linux-2.6.15-rc6-dt.orig/include/asm-i386/timer.h +++ linux-2.6.15-rc6-dt/include/asm-i386/timer.h @@ -1,5 +1,6 @@ #ifndef _ASMi386_TIMER_H #define _ASMi386_TIMER_H +#include <linux/jiffies.h> #include <linux/init.h> #include <linux/pm.h> @@ -19,7 +20,7 @@ */ struct timer_opts { char* name; - void (*mark_offset)(void); + int (*mark_offset)(void); unsigned long (*get_offset)(void); unsigned long long (*monotonic_clock)(void); void (*delay)(unsigned long); @@ -38,6 +39,9 @@ struct init_timer_opts { extern struct timer_opts* __init select_timer(void); extern void clock_fallback(void); void setup_pit_timer(void); +extern void disable_pit_timer(void); +extern void enable_pit_timer(void); +extern void reprogram_pit_timer(unsigned long jiffies_to_skip); /* Modifiers for buggy PIT handling */ @@ -67,4 +71,37 @@ extern unsigned long calibrate_tsc_hpet( #ifdef CONFIG_X86_PM_TIMER extern struct init_timer_opts timer_pmtmr_init; #endif +#ifdef CONFIG_NO_IDLE_HZ +static inline void tsc_sanity_check(int lost) +{ +} +#else /* CONFIG_NO_IDLE_HZ */ +extern void cpufreq_delayed_get(void); + +static inline void tsc_sanity_check(int lost) +{ + static int lost_count = 0; + + if (lost >= 2) { + jiffies_64 += lost-1; + + /* sanity check to ensure we're not always losing ticks */ + if (lost_count++ > 100) { + printk(KERN_WARNING "Losing too many ticks!\n"); + printk(KERN_WARNING "TSC cannot be used as a timesource. \n"); + printk(KERN_WARNING "Possible reasons for this are:\n"); + printk(KERN_WARNING " You're running with Speedstep,\n"); + printk(KERN_WARNING " You don't have DMA enabled for your hard disk (see hdparm),\n"); + printk(KERN_WARNING " Incorrect TSC synchronization on an SMP system (see dmesg).\n"); + printk(KERN_WARNING "Falling back to a sane timesource now.\n"); + + clock_fallback(); + } + /* ... but give the TSC a fair chance */ + if (lost_count > 25) + cpufreq_delayed_get(); + } else + lost_count = 0; +} +#endif /* CONFIG_NO_IDLE_HZ */ #endif Index: linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_cyclone.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/timers/timer_cyclone.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_cyclone.c @@ -45,7 +45,7 @@ static seqlock_t monotonic_lock = SEQLOC } while (high != cyclone_timer[1]); -static void mark_offset_cyclone(void) +static int mark_offset_cyclone(void) { unsigned long lost, delay; unsigned long delta = last_cyclone_low; @@ -101,6 +101,8 @@ static void mark_offset_cyclone(void) */ if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ)) jiffies_64++; + + return lost; } static unsigned long get_offset_cyclone(void) Index: linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_hpet.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/timers/timer_hpet.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_hpet.c @@ -101,7 +101,7 @@ static unsigned long get_offset_hpet(voi return edx; } -static void mark_offset_hpet(void) +static int mark_offset_hpet(void) { unsigned long long this_offset, last_offset; unsigned long offset; @@ -124,6 +124,8 @@ static void mark_offset_hpet(void) 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); + + return 1; } static void delay_hpet(unsigned long loops) Index: linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_none.c =================================================================== --- linux-2.6.15-rc6-dt.orig/arch/i386/kernel/timers/timer_none.c +++ linux-2.6.15-rc6-dt/arch/i386/kernel/timers/timer_none.c @@ -1,9 +1,10 @@ #include <linux/init.h> #include <asm/timer.h> -static void mark_offset_none(void) +static int mark_offset_none(void) { /* nothing needed */ + return 1; } static unsigned long get_offset_none(void) Index: linux-2.6.15-rc6-dt/kernel/timer_top.c =================================================================== --- /dev/null +++ linux-2.6.15-rc6-dt/kernel/timer_top.c @@ -0,0 +1,234 @@ +/* + * kernel/timer_top.c + * + * Export Timers information to /proc/timer_info + * + * Copyright (C) 2005 Instituto Nokia de Tecnologia - INdT - Manaus + * Written by Daniel Petrini <[email protected]> + * + * This utility should be used to get information from the system timers + * and maybe optimize the system once you know which timers are being used + * and the process which starts them. + * This is particular useful above dynamic tick implementation. One can + * see who is starting timers and make the HZ value increase. + * + * We export the addresses and counting of timer functions being called, + * the pid and cmdline from the owner process if applicable. + * + * 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 <linux/list.h> +#include <linux/proc_fs.h> +#include <linux/module.h> +#include <linux/spinlock.h> +#include <linux/sched.h> +#include <linux/seq_file.h> +#include <asm/uaccess.h> + +#define VERSION "Timer Top v0.9.8" + +struct timer_top_info { + unsigned int func_pointer; + unsigned long counter; + pid_t pid; + char comm[TASK_COMM_LEN]; + struct list_head list; +}; + +struct timer_top_root { + spinlock_t lock; + struct list_head list; + kmem_cache_t *cache; + int record; /* if currently collecting data */ +}; + +static struct timer_top_root top_root = { + .lock = SPIN_LOCK_UNLOCKED, + .list = LIST_HEAD_INIT(top_root.list), +}; + +static struct list_head *timer_list = &top_root.list; +static spinlock_t *top_lock = &top_root.lock; + +static inline int update_top_info(unsigned long function, pid_t pid_info) +{ + struct timer_top_info *top; + + list_for_each_entry(top, timer_list, list) { + /* if it is in the list increment its count */ + if (top->func_pointer == function && top->pid == pid_info) { + top->counter++; + return 1; + } + } + + return 0; +} + +int account_timer(unsigned long function, unsigned long data) +{ + struct timer_top_info *top; + struct task_struct * task_info; + pid_t pid_info = 0; + char name[TASK_COMM_LEN] = ""; + unsigned long flags; + + if (!top_root.record) + goto out; + + spin_lock_irqsave(top_lock, flags); + + if (data) { + task_info = (struct task_struct *) data; + /* little sanity ... not enough yet */ + if ((task_info->pid > 0) && (task_info->pid < PID_MAX_LIMIT)) { + pid_info = task_info->pid; + strncpy(name, task_info->comm, sizeof(task_info->comm)); + } + } + + if (update_top_info(function, pid_info)) + goto out_unlock; + + /* Function not found so insert it in the list */ + top = kmem_cache_alloc(top_root.cache, GFP_ATOMIC); + if (unlikely(!top)) + goto out_unlock; + + top->func_pointer = function; + top->counter = 1; + top->pid = pid_info; + strncpy(top->comm, name, sizeof(name)); + list_add(&top->list, timer_list); + +out_unlock: + spin_unlock_irqrestore(top_lock, flags); + +out: + return 0; +} + +EXPORT_SYMBOL(account_timer); + +/* + * Must hold top_lock + */ +static void timer_list_del(void) +{ + struct list_head *aux1, *aux2; + struct timer_top_info *entry; + + list_for_each_safe(aux1, aux2, timer_list) { + entry = list_entry(aux1, struct timer_top_info, list); + list_del(aux1); + kmem_cache_free(top_root.cache, entry); + } +} + +/* PROC_FS_SECTION */ + +static struct proc_dir_entry *top_info_file; +static struct proc_dir_entry *top_info_file_out; + +/* Statistics output - timer_info*/ +static int proc_read_top_info(struct seq_file *m, void *v) +{ + struct timer_top_info *top; + + seq_printf(m, "Function counter - %s\n", VERSION); + + list_for_each_entry(top, timer_list, list) { + seq_printf(m, "%x %lu %d %s\n", top->func_pointer, + top->counter, top->pid, top->comm); + } + + if (!top_root.record) + seq_printf(m, "Disabled\n"); + + return 0; +} + +static int proc_timertop_open(struct inode *inode, struct file *file) +{ + return single_open(file, proc_read_top_info, NULL); +} + +static struct file_operations proc_timertop_operations = { + .open = proc_timertop_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +#define MAX_INPUT_TOP 10 + +/* Receive some commands from user - timer_input */ +static int proc_write_timer_input(struct file *file, const char *page, + unsigned long count, void *data) +{ + int len; + char input_data[MAX_INPUT_TOP]; + unsigned long flags; + + /* input size checking */ + if (count > MAX_INPUT_TOP - 1) + len = MAX_INPUT_TOP - 1; + else + len = count; + + if (copy_from_user(input_data, page, len)) + return -EFAULT; + + input_data[len] = '\0'; + + spin_lock_irqsave(top_lock, flags); + if (!strncmp(input_data, "clear", 5)) + timer_list_del(); + else if (!strncmp(input_data, "start", 5)) + top_root.record = 1; + else if (!strncmp(input_data, "stop", 4)) { + top_root.record = 0; + timer_list_del(); + } + spin_unlock_irqrestore(top_lock, flags); + + return len; +} + +/* Print a sample string showing the possible inputs - timer_input */ +static int proc_read_timer_input(char *page, char **start, off_t off, + int count, int *eof, void *data) +{ + int len = sprintf(page, "clear start stop\n"); + + return len; +} + +static int __init init_top_info(void) +{ + top_root.cache = kmem_cache_create("top_info", + sizeof(struct timer_top_info), 0, SLAB_PANIC, NULL, NULL); + + top_info_file = create_proc_entry("timer_info", 0444, NULL); + if (top_info_file == NULL) + return -ENOMEM; + + top_info_file_out = create_proc_entry("timer_input", 0666, NULL); + if (top_info_file_out == NULL) + return -ENOMEM; + + /* Statistics output */ + top_info_file->proc_fops = &proc_timertop_operations; + + /* Control */ + top_info_file_out->write_proc = &proc_write_timer_input; + top_info_file_out->read_proc = &proc_read_timer_input; + + return 0; +} + +module_init(init_top_info); Index: linux-2.6.15-rc6-dt/lib/Kconfig.debug =================================================================== --- linux-2.6.15-rc6-dt.orig/lib/Kconfig.debug +++ linux-2.6.15-rc6-dt/lib/Kconfig.debug @@ -77,6 +77,19 @@ config SCHEDSTATS application, you can say N to avoid the very slight overhead this adds. +config TIMER_INFO + bool "Collect kernel timers statistics" + depends on DEBUG_KERNEL && PROC_FS && NO_IDLE_HZ + help + If you say Y here, additional code will be inserted into the + timer routines to collect statistics about kernel timers being + reprogrammed through dynamic ticks feature. The statistics + will be provided in /proc/timer_info and the behavior of this + feature can be controlled through /proc/timer_input. + The goal is to offer some output to let user applications show + timer pattern usage and allow some tuning in them to + maximise idle time. + config DEBUG_SLAB bool "Debug memory allocations" depends on DEBUG_KERNEL Index: linux-2.6.15-rc6-dt/drivers/acpi/processor_idle.c =================================================================== --- linux-2.6.15-rc6-dt.orig/drivers/acpi/processor_idle.c +++ linux-2.6.15-rc6-dt/drivers/acpi/processor_idle.c @@ -38,6 +38,7 @@ #include <linux/dmi.h> #include <linux/moduleparam.h> #include <linux/sched.h> /* need_resched() */ +#include <linux/dyn-tick.h> #include <asm/io.h> #include <asm/uaccess.h> @@ -60,6 +61,8 @@ module_param(max_cstate, uint, 0644); static unsigned int nocst = 0; module_param(nocst, uint, 0000); +#define BM_JIFFIES (HZ >= 800 ? 4 : 2) + /* * bm_history -- bit-mask with a bit per jiffy of bus-master activity * 1000 HZ: 0xFFFFFFFF: 32 jiffies = 32ms @@ -256,10 +259,10 @@ static void acpi_processor_idle(void) pr->power.bm_check_timestamp = jiffies; /* - * Apply bus mastering demotion policy. Automatically demote + * If bus mastering is or was active this jiffy, demote * to avoid a faulty transition. Note that the processor * won't enter a low-power state during this call (to this - * funciton) but should upon the next. + * function) but should upon the next. * * TBD: A better policy might be to fallback to the demotion * state (use it for this quantum only) istead of @@ -267,14 +270,60 @@ static void acpi_processor_idle(void) * qualification. This may, however, introduce DMA * issues (e.g. floppy DMA transfer overrun/underrun). */ - if (pr->power.bm_activity & cx->demotion.threshold.bm) { + if ((pr->power.bm_activity & 0x01) && + cx->demotion.threshold.bm) { local_irq_enable(); next_state = cx->demotion.state; + if (dyn_tick_enabled()) + dyn_early_reprogram(BM_JIFFIES); + /* do not promote in fast-path */ + pr->power.last_sleep = 0; goto end; } } - cx->usage++; + /* + * Some special policy tweaks for dynamic ticks + */ + if (dyn_tick_enabled()) { + /* + * Fast-path promotion: if we slept for more than 2 jiffies the + * last time, and we're intended to sleep for more than 2 + * jiffies now, promote. Note that the processor won't enter a + * low-power state during this call (to this funciton) but + * should upon the next. + */ + if (cx->promotion.state && cx->promotion.count && + dyn_tick_skipping() && ((pr->power.last_sleep > + (BM_JIFFIES * cx->promotion.threshold.ticks)) || + (pr->power.quick_promotion == 1)) && + (dyn_tick_current_skip() > BM_JIFFIES)) { + local_irq_enable(); + next_state = cx->promotion.state; + goto end; + } + + + /* + * Fast-path demotion: if we're going to sleep for only one + * jiffy, and we'd enter C3-type sleep, and the wakeup latency + * is high, don't use C3-type sleep but (temporarily) C2. + */ + if (cx->demotion.state && cx->demotion.threshold.bm && + (dyn_tick_next_tick() < (jiffies + 1)) + && (cx->latency > 150)) { + local_irq_enable(); + next_state = cx->demotion.state; + + /* don't do a fast-path promotion next time... */ + pr->power.last_sleep = 0; + /* ... but thereafter. */ + pr->power.quick_promotion = 2; + goto end; + } + } + + pr->power.last_sleep = 0; #ifdef CONFIG_HOTPLUG_CPU /* @@ -383,9 +432,22 @@ static void acpi_processor_idle(void) local_irq_enable(); return; } + cx->usage++; + if (cx->type != ACPI_STATE_C1) { + if (sleep_ticks > 0) + cx->time += sleep_ticks; + } + + pr->power.last_sleep = sleep_ticks / (PM_TIMER_FREQUENCY / HZ); + + if (pr->flags.bm_check) + pr->power.bm_check_timestamp += pr->power.last_sleep; next_state = pr->power.state; + if (pr->power.quick_promotion) + pr->power.quick_promotion--; + /* * Promotion? * ---------- @@ -988,9 +1050,10 @@ static int acpi_processor_power_seq_show else seq_puts(seq, "demotion[--] "); - seq_printf(seq, "latency[%03d] usage[%08d]\n", + seq_printf(seq, "latency[%03d] usage[%08d] time[%020llu]\n", pr->power.states[i].latency, - pr->power.states[i].usage); + pr->power.states[i].usage, + pr->power.states[i].time); } end: Index: linux-2.6.15-rc6-dt/include/acpi/processor.h =================================================================== --- linux-2.6.15-rc6-dt.orig/include/acpi/processor.h +++ linux-2.6.15-rc6-dt/include/acpi/processor.h @@ -51,6 +51,7 @@ struct acpi_processor_cx { u32 latency_ticks; u32 power; u32 usage; + u64 time; struct acpi_processor_cx_policy promotion; struct acpi_processor_cx_policy demotion; }; @@ -60,6 +61,8 @@ struct acpi_processor_power { unsigned long bm_check_timestamp; u32 default_state; u32 bm_activity; + u16 last_sleep; + u16 quick_promotion; int count; struct acpi_processor_cx states[ACPI_PROCESSOR_MAX_POWER];
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