As promised, here is an updated patch for the newly released 2.6.13-rc5. Boots and runs fine on P4HT (SMP+SMT kernel) built with gcc 4.0.1. Cheers, Con ---
This is the dynamic ticks patch for i386 as written by Tony Lindgen <[email protected]> and Tuukka Tikkanen <[email protected]>. This version of the patch includes code style cleanups by Con Kolivas. Signed-off-by: Con Kolivas <[email protected]> arch/i386/Kconfig | 33 +++++ arch/i386/kernel/Makefile | 1 arch/i386/kernel/apic.c | 19 +++ arch/i386/kernel/dyn-tick.c | 149 +++++++++++++++++++++++++ arch/i386/kernel/irq.c | 3 arch/i386/kernel/process.c | 3 arch/i386/kernel/time.c | 7 - arch/i386/kernel/timers/timer_pit.c | 37 ++++++ arch/i386/kernel/timers/timer_pm.c | 4 arch/i386/kernel/timers/timer_tsc.c | 10 + arch/i386/mach-default/setup.c | 16 ++ include/asm-i386/dyn-tick.h | 78 +++++++++++++ include/linux/dyn-tick.h | 66 +++++++++++ kernel/Makefile | 1 kernel/dyn-tick.c | 212 ++++++++++++++++++++++++++++++++++++ 15 files changed, 636 insertions(+), 3 deletions(-) Index: linux-2.6.13-rc5-ck1/arch/i386/Kconfig =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/Kconfig 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/Kconfig 2005-08-02 21:14:35.000000000 +1000 @@ -457,6 +457,39 @@ config HPET_EMULATE_RTC bool "Provide RTC interrupt" depends on HPET_TIMER && RTC=y +config NO_IDLE_HZ + bool "Dynamic Tick Timer - Skip timer ticks during idle" + depends on EXPERIMENTAL + 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-2.6.13-rc5-ck1/arch/i386/kernel/apic.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/apic.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/apic.c 2005-08-02 21:18:48.000000000 +1000 @@ -27,6 +27,7 @@ #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> @@ -931,6 +932,8 @@ void (*wait_timer_tick)(void) __devinitd #define APIC_DIVISOR 16 +u32 apic_timer_val; + static void __setup_APIC_LVTT(unsigned int clocks) { unsigned int lvtt_value, tmp_value, ver; @@ -949,7 +952,12 @@ 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 / APIC_DIVISOR; + + if (apic_timer_val) + set_dyn_tick_max_skip(apic_timer_val); + + apic_write_around(APIC_TMICT, apic_timer_val); } static void __devinit setup_APIC_timer(unsigned int clocks) @@ -1062,6 +1070,8 @@ void __init setup_boot_APIC_clock(void) */ setup_APIC_timer(calibration_result); + setup_dyn_tick_use_apic(calibration_result); + local_irq_enable(); } @@ -1200,6 +1210,13 @@ fastcall void smp_apic_timer_interrupt(s * interrupt lock, which is the WrongThing (tm) to do. */ irq_enter(); + + /* + * Check if we need to wake up PIT interrupt handler. + * Otherwise just wake up local APIC timer. + */ + wakeup_pit_or_apic(cpu, regs); + smp_local_timer_interrupt(regs); irq_exit(); } Index: linux-2.6.13-rc5-ck1/arch/i386/kernel/dyn-tick.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/dyn-tick.c 2005-01-12 16:19:45.000000000 +1100 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/dyn-tick.c 2005-08-02 21:20:14.000000000 +1000 @@ -0,0 +1,149 @@ +/* + * linux/arch/i386/kernel/dyn-tick.c + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[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 <asm/apic.h> + +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); + +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; +} + +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; +} + +/* Functions that need blank prototypes for !CONFIG_NO_IDLE_HZ below here */ +inline void set_dyn_tick_max_skip(u32 apic_timer_val) +{ + dyn_tick->max_skip = 0xffffff / apic_timer_val; +} + +inline void setup_dyn_tick_use_apic(unsigned int calibration_result) +{ + if (calibration_result) + dyn_tick->state |= DYN_TICK_USE_APIC; + else + printk(KERN_INFO "dyn-tick: Cannot use local APIC\n"); +} + +void wakeup_pit_or_apic(int cpu, struct pt_regs *regs) +{ + unsigned long seq; + + 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)); +} + +void dyn_tick_interrupt(int irq, struct pt_regs *regs) +{ + if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING) && irq) + dyn_tick->interrupt(irq, NULL, regs); +} + +void dyn_tick_time_init(struct timer_opts *cur_timer) +{ + 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); +} Index: linux-2.6.13-rc5-ck1/arch/i386/kernel/irq.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/irq.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/irq.c 2005-08-02 20:45:28.000000000 +1000 @@ -18,6 +18,7 @@ #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/delay.h> +#include <linux/dyn-tick.h> DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_maxaligned_in_smp; EXPORT_PER_CPU_SYMBOL(irq_stat); @@ -76,6 +77,8 @@ fastcall unsigned int do_IRQ(struct pt_r } #endif + dyn_tick_interrupt(irq, regs); + #ifdef CONFIG_4KSTACKS curctx = (union irq_ctx *) current_thread_info(); Index: linux-2.6.13-rc5-ck1/arch/i386/kernel/Makefile =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/Makefile 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/Makefile 2005-08-02 20:45:28.000000000 +1000 @@ -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-2.6.13-rc5-ck1/arch/i386/kernel/process.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/process.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/process.c 2005-08-02 21:39:28.000000000 +1000 @@ -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> @@ -200,6 +201,8 @@ void cpu_idle(void) if (cpu_is_offline(cpu)) play_dead(); + dyn_tick_reprogram_timer(); + __get_cpu_var(irq_stat).idle_timestamp = jiffies; idle(); } Index: linux-2.6.13-rc5-ck1/arch/i386/kernel/time.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/time.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/time.c 2005-08-02 20:45:28.000000000 +1000 @@ -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> @@ -252,7 +253,7 @@ 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, void *dev_id, +inline void do_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) { #ifdef CONFIG_X86_IO_APIC @@ -423,7 +424,7 @@ 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, }; @@ -479,5 +480,7 @@ 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-2.6.13-rc5-ck1/arch/i386/kernel/timers/timer_pit.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/timers/timer_pit.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/timers/timer_pit.c 2005-08-02 20:45:28.000000000 +1000 @@ -148,6 +148,43 @@ static unsigned long get_offset_pit(void 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 = { Index: linux-2.6.13-rc5-ck1/arch/i386/kernel/timers/timer_pm.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/timers/timer_pm.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/timers/timer_pm.c 2005-08-02 20:45:28.000000000 +1000 @@ -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> @@ -168,6 +169,9 @@ static void mark_offset_pmtmr(void) 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-2.6.13-rc5-ck1/arch/i386/kernel/timers/timer_tsc.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/kernel/timers/timer_tsc.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/kernel/timers/timer_tsc.c 2005-08-02 20:45:28.000000000 +1000 @@ -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> @@ -367,6 +368,9 @@ static void mark_offset_tsc(void) 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 */ @@ -434,11 +438,17 @@ static void mark_offset_tsc(void) 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-2.6.13-rc5-ck1/arch/i386/mach-default/setup.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/arch/i386/mach-default/setup.c 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/arch/i386/mach-default/setup.c 2005-08-02 21:21:22.000000000 +1000 @@ -93,6 +93,22 @@ void __init time_init_hook(void) 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-2.6.13-rc5-ck1/include/asm-i386/dyn-tick.h =================================================================== --- linux-2.6.13-rc5-ck1.orig/include/asm-i386/dyn-tick.h 2005-01-12 16:19:45.000000000 +1100 +++ linux-2.6.13-rc5-ck1/include/asm-i386/dyn-tick.h 2005-08-02 21:43:21.000000000 +1000 @@ -0,0 +1,78 @@ +/* + * linux/include/asm-i386/dyn-tick.h + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[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_ + +#ifdef CONFIG_NO_IDLE_HZ +extern int dyn_tick_arch_init(void); +extern void disable_pit_timer(void); +extern void reprogram_pit_timer(int jiffies_to_skip); +extern void replace_timer_interrupt(void * new_handler); +extern void set_dyn_tick_max_skip(u32 apic_timer_val); +extern void setup_dyn_tick_use_apic(unsigned int calibration_result); +extern void wakeup_pit_or_apic(int cpu, struct pt_regs *regs); +extern void dyn_tick_interrupt(int irq, struct pt_regs *regs); +extern void dyn_tick_time_init(struct timer_opts *cur_timer); +extern void do_timer_interrupt(int irq, void *dev_id, + struct pt_regs *regs); +extern irqreturn_t dyn_tick_timer_interrupt(int irq, void *dev_id, + struct pt_regs *regs); +extern int __init dyn_tick_arch_init(void); + +extern u32 apic_timer_val; + +#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 + +static inline void reprogram_apic_timer(unsigned int count) +{ +#ifdef CONFIG_X86_LOCAL_APIC + unsigned long flags; + + count *= apic_timer_val; + local_irq_save(flags); + apic_write_around(APIC_TMICT, count); + local_irq_restore(flags); +#endif /* CONFIG_X86_LOCAL_APIC */ +} + +#else /* CONFIG_NO_IDLE_HZ */ +static inline void set_dyn_tick_max_skip(u32 apic_timer_val) +{ +} + +static inline void reprogram_apic_timer(unsigned int count) +{ +} + +static inline void setup_dyn_tick_use_apic(unsigned int calibration_result) +{ +} + +static inline void wakeup_pit_or_apic(int cpu, struct pt_regs *regs) +{ +} + +static inline void dyn_tick_interrupt(int irq, struct pt_regs *regs) +{ +} + +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-2.6.13-rc5-ck1/include/linux/dyn-tick.h =================================================================== --- linux-2.6.13-rc5-ck1.orig/include/linux/dyn-tick.h 2005-01-12 16:19:45.000000000 +1100 +++ linux-2.6.13-rc5-ck1/include/linux/dyn-tick.h 2005-08-02 21:41:01.000000000 +1000 @@ -0,0 +1,66 @@ +/* + * linux/include/linux/dyn-tick.h + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[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> +#include <asm/timer.h> + +#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 <asm/dyn-tick.h> + +#endif /* _DYN_TICK_TIMER_H */ Index: linux-2.6.13-rc5-ck1/kernel/dyn-tick.c =================================================================== --- linux-2.6.13-rc5-ck1.orig/kernel/dyn-tick.c 2005-01-12 16:19:45.000000000 +1100 +++ linux-2.6.13-rc5-ck1/kernel/dyn-tick.c 2005-08-02 21:02:44.000000000 +1000 @@ -0,0 +1,212 @@ +/* + * linux/kernel/dyn-tick.c + * + * Beginnings of generic dynamic tick timer support + * + * Copyright (C) 2004 Nokia Corporation + * Written by Tony Lindgen <[email protected]> and + * Tuukka Tikkanen <[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 <asm/io.h> + +#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 independent 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-2.6.13-rc5-ck1/kernel/Makefile =================================================================== --- linux-2.6.13-rc5-ck1.orig/kernel/Makefile 2005-08-02 20:45:19.000000000 +1000 +++ linux-2.6.13-rc5-ck1/kernel/Makefile 2005-08-02 20:45:28.000000000 +1000 @@ -30,6 +30,7 @@ obj-$(CONFIG_SYSFS) += ksysfs.o obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(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 <[email protected]>, the -fno-omit-frame-pointer is
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