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Subject[PATCH] i386 No-Idle-Hz aka Dynamic-Ticks 4
Date
Here's my most current version of the dynamic ticks patch for i386 with some 
more minor cleanups already discussed and cosmetic changes ( also available
at http://ck.kolivas.org/patches/dyn-ticks/ ).

Cheers,
Con
---


Index: linux-2.6.13-rc5-ck2/arch/i386/Kconfig
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/Kconfig 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/Kconfig 2005-08-05 20:44:28.000000000 +1000
@@ -457,6 +457,41 @@ 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 can disable dynamic tick timer either by
+ passing dyntick=disable command line option, or via sysfs:
+
+ # echo 0 > /sys/devices/system/dyn_tick/dyn_tick0/enable
+
+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, however on MOST recent hardware disabling the PIT
+ timer also disables APIC timer interrupts, and the system won't
+ run properly. Symptoms include slow system boot, and time running
+ slow.
+
+ If unsure, do NOT enable this option.
+
+ Note that you can disable apic usage by dynamic tick timer
+ either by passing dyntick=noapic command line option, or via
+ sysfs:
+
+ # echo 0 > /sys/devices/system/dyn_tick/dyn_tick0/useapic
+
config SMP
bool "Symmetric multi-processing support"
---help---
Index: linux-2.6.13-rc5-ck2/arch/i386/kernel/apic.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/apic.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/apic.c 2005-08-05 20:42:18.000000000 +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-ck2/arch/i386/kernel/dyn-tick.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/dyn-tick.c 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/dyn-tick.c 2005-08-05 20:48:57.000000000 +1000
@@ -0,0 +1,150 @@
+/*
+ * linux/arch/i386/kernel/dyn-tick.c
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@atomide.com> and
+ * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ *
+ * 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 custom 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-ck2/arch/i386/kernel/irq.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/irq.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/irq.c 2005-08-05 20:42:18.000000000 +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-ck2/arch/i386/kernel/Makefile
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/Makefile 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/Makefile 2005-08-05 20:42:18.000000000 +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-ck2/arch/i386/kernel/process.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/process.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/process.c 2005-08-05 20:42:18.000000000 +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-ck2/arch/i386/kernel/time.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/time.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/time.c 2005-08-05 20:50:38.000000000 +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>
@@ -252,8 +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,
- struct pt_regs *regs)
+void do_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
#ifdef CONFIG_X86_IO_APIC
if (timer_ack) {
@@ -423,7 +423,7 @@ 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 +479,7 @@ 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-ck2/arch/i386/kernel/timers/timer_pit.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/timers/timer_pit.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/timers/timer_pit.c 2005-08-05 20:51:37.000000000 +1000
@@ -148,6 +148,44 @@ 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-ck2/arch/i386/kernel/timers/timer_pm.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/timers/timer_pm.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/timers/timer_pm.c 2005-08-05 20:42:18.000000000 +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-ck2/arch/i386/kernel/timers/timer_tsc.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/kernel/timers/timer_tsc.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/kernel/timers/timer_tsc.c 2005-08-05 20:42:18.000000000 +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>
@@ -166,10 +167,19 @@ 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)
{
- unsigned long long this_offset, last_offset;
+ unsigned long long last_offset;
unsigned long offset, temp, hpet_current;

write_seqlock(&monotonic_lock);
@@ -197,9 +207,7 @@ static void mark_offset_tsc_hpet(void)
}
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 */
@@ -346,7 +354,7 @@ static void mark_offset_tsc(void)
int count;
int countmp;
static int count1 = 0;
- unsigned long long this_offset, last_offset;
+ unsigned long long last_offset;
static int lost_count = 0;

write_seqlock(&monotonic_lock);
@@ -367,6 +375,12 @@ static void mark_offset_tsc(void)

rdtsc(last_tsc_low, last_tsc_high);

+ if (dyn_tick_enabled()) {
+ update_monotonic_base(last_offset);
+ write_sequnlock(&monotonic_lock);
+ return;
+ }
+
spin_lock(&i8253_lock);
outb_p(0x00, PIT_MODE); /* latch the count ASAP */

@@ -434,9 +448,8 @@ static void mark_offset_tsc(void)
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 */
Index: linux-2.6.13-rc5-ck2/arch/i386/mach-default/setup.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/arch/i386/mach-default/setup.c 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/arch/i386/mach-default/setup.c 2005-08-05 20:42:18.000000000 +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-ck2/include/asm-i386/dyn-tick.h
===================================================================
--- linux-2.6.13-rc5-ck2.orig/include/asm-i386/dyn-tick.h 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-rc5-ck2/include/asm-i386/dyn-tick.h 2005-08-05 20:57:02.000000000 +1000
@@ -0,0 +1,85 @@
+/*
+ * linux/include/asm-i386/dyn-tick.h
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@atomide.com> and
+ * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ *
+ * 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>
+
+#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
+
+#if defined(CONFIG_DYN_TICK_USE_APIC)
+#define dyntick_apicable() 1
+#else
+#define dyntick_apicable() 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-ck2/include/linux/dyn-tick.h
===================================================================
--- linux-2.6.13-rc5-ck2.orig/include/linux/dyn-tick.h 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-rc5-ck2/include/linux/dyn-tick.h 2005-08-05 20:56:42.000000000 +1000
@@ -0,0 +1,61 @@
+/*
+ * linux/include/linux/dyn-tick.h
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@atomide.com> and
+ * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ *
+ * 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_APICABLE (1 << 5)
+#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)
+
+#define NS_TICK_LEN ((1 * 1000000000) / HZ)
+#define DYN_TICK_MIN_SKIP 2
+
+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);
+
+#ifdef CONFIG_NO_IDLE_HZ
+extern unsigned long dyn_tick_reprogram_timer(void);
+
+#define dyn_tick_enabled() (dyn_tick->state & DYN_TICK_ENABLED)
+#else /* CONFIG_NO_IDLE_HZ */
+#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-ck2/kernel/dyn-tick.c
===================================================================
--- linux-2.6.13-rc5-ck2.orig/kernel/dyn-tick.c 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-rc5-ck2/kernel/dyn-tick.c 2005-08-05 21:02:44.000000000 +1000
@@ -0,0 +1,273 @@
+/*
+ * linux/kernel/dyn-tick.c
+ *
+ * Beginnings of generic dynamic tick timer support
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@atomide.com> and
+ * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ *
+ * 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"
+#define DYN_TICK_IS_SET(x) ((dyn_tick->state & (x)) == (x))
+
+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_IS_SET(DYN_TICK_ENABLED))
+ return 0;
+
+ /* Check if we are already skipping ticks and can idle other cpus */
+ if (DYN_TICK_IS_SET(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 = 1;
+static int __initdata dyntick_useapic = 1;
+
+/*
+ * dyntick=[disable],[noapic]
+ */
+static int __init dyntick_setup(char *options)
+{
+ if (!options)
+ return 0;
+
+ if (!strncmp(options, "disable", 6))
+ dyntick_autoenable = 0;
+
+ if (strstr(options, "noapic"))
+ dyntick_useapic = 0;
+
+ return 0;
+}
+
+__setup("dyntick=", dyntick_setup);
+
+/*
+ * ---------------------------------------------------------------------------
+ * Sysfs interface
+ * ---------------------------------------------------------------------------
+ */
+
+extern struct sys_device device_timer;
+
+static ssize_t show_dyn_tick_state(struct sys_device *dev, char *buf)
+{
+ return sprintf(buf,
+ "suitable:\t%i\n"
+ "enabled:\t%i\n"
+ "apic suitable:\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_APICABLE),
+ DYN_TICK_IS_SET(DYN_TICK_USE_APIC));
+}
+
+static ssize_t show_dyn_tick_enable(struct sys_device *dev, char *buf)
+{
+ return sprintf(buf, "enabled:\t%i\n",
+ DYN_TICK_IS_SET(DYN_TICK_ENABLED));
+}
+
+static ssize_t set_dyn_tick_enable(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 ssize_t show_dyn_tick_useapic(struct sys_device *dev, char *buf)
+{
+ return sprintf(buf, "using APIC:\t%i\n",
+ DYN_TICK_IS_SET(DYN_TICK_USE_APIC));
+}
+
+static ssize_t set_dyn_tick_useapic(struct sys_device *dev, const char *buf,
+ size_t count)
+{
+ unsigned long flags;
+ unsigned int enable = simple_strtoul(buf, NULL, 2);
+
+ if (!DYN_TICK_IS_SET(DYN_TICK_APICABLE))
+ goto out;
+ write_seqlock_irqsave(&xtime_lock, flags);
+ if (enable)
+ dyn_tick->state |= DYN_TICK_USE_APIC;
+ else
+ dyn_tick->state &= ~DYN_TICK_USE_APIC;
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+out:
+ return count;
+}
+
+static SYSDEV_ATTR(state, 0444, show_dyn_tick_state, NULL);
+static SYSDEV_ATTR(enable, 0644, show_dyn_tick_enable,
+ set_dyn_tick_enable);
+static SYSDEV_ATTR(useapic, 0644, show_dyn_tick_useapic,
+ set_dyn_tick_useapic);
+
+static struct sysdev_class dyn_tick_sysclass = {
+ set_kset_name("dyn_tick"),
+};
+
+static struct sys_device device_dyn_tick = {
+ .id = 0,
+ .cls = &dyn_tick_sysclass,
+};
+
+static int init_dyn_tick_sysfs(void)
+{
+ int error = 0;
+ if ((error = sysdev_class_register(&dyn_tick_sysclass)))
+ goto out;
+ if ((error = sysdev_register(&device_dyn_tick)))
+ goto out;
+ if ((error = sysdev_create_file(&device_dyn_tick, &attr_state)))
+ goto out;
+ if ((error = sysdev_create_file(&device_dyn_tick, &attr_enable)))
+ goto out;
+ error = sysdev_create_file(&device_dyn_tick, &attr_useapic);
+
+out:
+ return error;
+}
+
+device_initcall(init_dyn_tick_sysfs);
+
+/*
+ * ---------------------------------------------------------------------------
+ * 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_IS_SET(DYN_TICK_SUITABLE)) {
+ printk(KERN_ERR "dyn-tick: No suitable timer found\n");
+ return -ENODEV;
+ }
+
+ if (dyntick_apicable())
+ dyn_tick->state |= DYN_TICK_APICABLE;
+ if (!dyntick_useapic || !DYN_TICK_IS_SET(DYN_TICK_APICABLE))
+ dyn_tick->state &= ~DYN_TICK_USE_APIC;
+
+ if ((ret = dyn_tick_cfg->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: 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-ck2/kernel/Makefile
===================================================================
--- linux-2.6.13-rc5-ck2.orig/kernel/Makefile 2005-08-05 20:41:44.000000000 +1000
+++ linux-2.6.13-rc5-ck2/kernel/Makefile 2005-08-05 20:42:18.000000000 +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 <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
\
 
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