Re: [PATCH] i386 No Idle HZ aka dynticks 051221

From: Theodore Ts'o
Date: Sun Dec 25 2005 - 12:16:01 EST

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So I took Linus's advice and am the process of trying out 2.6.15rc7,
and in I needed to rebase the dyntick patch to apply against rc7.
Here's what I came up with....

- Ted

Here is the latest version of the dynticks code incorporating a huge rewrite
correcting all the known problems with the previous code.

Major Changes:

All the tick skipping data is per cpu now, allowing each cpu to skip ticks
according to its own timers. The data for the next scheduled tick is also
available based on this information allowing it to be used when all cpus are
idle (eg to disable the PIT timer).

Management of APIC on SMP and UP now has a boottime check that determines the
best way to reprogram the timer, and selects the most reliable one.
Unfortunately, being i386 this is almost always PIT reprogramming on UP (now
the APIC is disabled when this is used) and APIC reprogramming per CPU but PIT
reprogramming when all cpus are idle.

Bugs fixed:
This corrects the problem of too many interrupts on SMP
SMP reprogramming now is actually timer correct
The cpu accounting is now correct
The stalling on UP machines with local apic requiring keypresses was abolished
The maximum number of APIC ticks to skip is allowed to be as high as possible
instead of some arbitrary maximum
Runtime overhead has been reduced
Tick rates are lower than ever (on a single user console on SMP it idles at
18HZ)

There are now no known bugs. Of course that doesn't mean there won't be...

Please test and comment.

Power savings on laptops vary from .3 to 2W. The higher the cpu frequency,
the more the power savings are (when idle).

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: 2.6.15-rc7/include/linux/dyn-tick.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6.15-rc7/include/linux/dyn-tick.h 2005-12-25 10:59:57.000000000 -0500
@@ -0,0 +1,113 @@
+/*
+ * linux/include/linux/dyn-tick.h
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ * Rewritten by Con Kolivas <kernel@xxxxxxxxxxx>
+ *
+ * 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)
+
+/* Don't skip longer than NMI */
+#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 tick; /* The next earliest tick */
+};
+
+typedef struct {
+ unsigned long next_tick; /* Next tick we're skipping to */
+ unsigned long skip; /* Ticks we're currently skipping */
+ unsigned int nohz_cpu; /* This cpu is idle */
+} ____cacheline_aligned dyn_tick_data;
+
+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(dyn_tick_data, dyn_cpu);
+extern dyn_tick_data dyn_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: 2.6.15-rc7/include/linux/timer.h
===================================================================
--- 2.6.15-rc7.orig/include/linux/timer.h 2005-12-25 00:01:50.000000000 -0500
+++ 2.6.15-rc7/include/linux/timer.h 2005-12-25 10:59:57.000000000 -0500
@@ -97,5 +97,6 @@
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: 2.6.15-rc7/kernel/dyn-tick.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6.15-rc7/kernel/dyn-tick.c 2005-12-25 10:59:57.000000000 -0500
@@ -0,0 +1,313 @@
+/*
+ * linux/kernel/dyn-tick.c
+ *
+ * Generic dynamic tick timer support
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ * Rewritten by Con Kolivas <kernel@xxxxxxxxxxx>
+ *
+ * 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 "051221"
+
+DEFINE_PER_CPU(dyn_tick_data, dyn_cpu);
+
+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.
+ */
+int dyn_tick_skipping(void)
+{
+ int ret = (get_cpu_var(dyn_cpu).next_tick > jiffies);
+
+ put_cpu_var(dyn_cpu);
+ return ret;
+}
+
+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 (get_cpu_var(dyn_cpu).next_tick > jiffies)
+ ret = __get_cpu_var(dyn_cpu).skip;
+ put_cpu_var(dyn_cpu);
+ 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 (get_cpu_var(dyn_cpu).next_tick > jiffies)
+ next = __get_cpu_var(dyn_cpu).next_tick;
+ put_cpu_var(dyn_cpu);
+ 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)
+{
+ unsigned long next = jiffies + delta;
+
+ __get_cpu_var(dyn_cpu).next_tick = next;
+ __get_cpu_var(dyn_cpu).skip = delta;
+ dyn_tick->arch_reprogram(next);
+ /* We have to update the idle_timestamp */
+ __get_cpu_var(irq_stat).idle_timestamp = next;
+ if (dyn_tick->tick <= jiffies || dyn_tick->tick > next)
+ dyn_tick->tick = next;
+}
+
+/*
+ * 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(dyn_cpu).nohz_cpu)
+ return;
+ __get_cpu_var(dyn_cpu).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;
+ if (delta > dyn_tick->max_skip)
+ delta = dyn_tick->max_skip;
+ if (delta > dyn_tick->min_skip) {
+ int idle_time = 0;
+
+ if (__get_cpu_var(dyn_cpu).next_tick == jiffies)
+ idle_time = __get_cpu_var(dyn_cpu).skip;
+ spin_lock(&dyn_tick->lock);
+ 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 >= get_cpu_var(dyn_cpu).next_tick &&
+ __get_cpu_var(dyn_cpu).next_tick > jiffies)
+ goto put_out;
+
+ 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);
+put_out:
+ put_cpu_var(dyn_cpu);
+}
+
+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: 2.6.15-rc7/kernel/Makefile
===================================================================
--- 2.6.15-rc7.orig/kernel/Makefile 2005-12-25 00:01:50.000000000 -0500
+++ 2.6.15-rc7/kernel/Makefile 2005-12-25 10:59:57.000000000 -0500
@@ -32,6 +32,8 @@
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 <alan@xxxxxxxxxxxxxxxx>, the -fno-omit-frame-pointer is
Index: 2.6.15-rc7/kernel/timer.c
===================================================================
--- 2.6.15-rc7.orig/kernel/timer.c 2005-12-25 00:01:50.000000000 -0500
+++ 2.6.15-rc7/kernel/timer.c 2005-12-25 10:59:57.000000000 -0500
@@ -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 @@
expires = nte->expires;
}
}
+ account_timer((unsigned long)nte->function, nte->data);
+
spin_unlock(&base->t_base.lock);
return expires;
}
@@ -869,6 +872,13 @@
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: 2.6.15-rc7/drivers/acpi/Kconfig
===================================================================
--- 2.6.15-rc7.orig/drivers/acpi/Kconfig 2005-12-25 00:01:32.000000000 -0500
+++ 2.6.15-rc7/drivers/acpi/Kconfig 2005-12-25 10:59:57.000000000 -0500
@@ -301,6 +301,8 @@
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: 2.6.15-rc7/arch/i386/defconfig
===================================================================
--- 2.6.15-rc7.orig/arch/i386/defconfig 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/arch/i386/defconfig 2005-12-25 10:59:57.000000000 -0500
@@ -91,6 +91,7 @@
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: 2.6.15-rc7/arch/i386/Kconfig
===================================================================
--- 2.6.15-rc7.orig/arch/i386/Kconfig 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/Kconfig 2005-12-25 10:59:57.000000000 -0500
@@ -173,6 +173,26 @@
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: 2.6.15-rc7/arch/i386/kernel/apic.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/apic.c 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/apic.c 2005-12-25 10:59:57.000000000 -0500
@@ -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 +934,8 @@

#define APIC_DIVISOR 16

+static u32 apic_timer_val __read_mostly;
+
static void __setup_APIC_LVTT(unsigned int clocks)
{
unsigned int lvtt_value, tmp_value, ver;
@@ -950,7 +954,9 @@
& ~(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;
+
+ apic_write_around(APIC_TMICT, apic_timer_val);
}

static void __devinit setup_APIC_timer(unsigned int clocks)
@@ -969,6 +975,17 @@
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;
+ 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 +1081,9 @@
*/
setup_APIC_timer(calibration_result);

+ setup_dyn_tick_use_apic(calibration_result);
+ set_dyn_tick_limits((0xFFFFFFFF / calibration_result) * APIC_DIVISOR, 0);
+
local_irq_restore(flags);
}

@@ -1202,6 +1222,9 @@
* interrupt lock, which is the WrongThing (tm) to do.
*/
irq_enter();
+
+ dyn_tick_interrupt(regs);
+
smp_local_timer_interrupt(regs);
irq_exit();
}
@@ -1214,6 +1237,9 @@
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 +1264,9 @@
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: 2.6.15-rc7/arch/i386/kernel/dyn-tick.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6.15-rc7/arch/i386/kernel/dyn-tick.c 2005-12-25 10:59:58.000000000 -0500
@@ -0,0 +1,340 @@
+/*
+ * linux/arch/i386/kernel/dyn-tick.c
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ * Rewritten by Con Kolivas <kernel@xxxxxxxxxxx>
+ *
+ * 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>
+
+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);
+}
+
+/*
+ * This is a special case that does pit reprogramming only when all cpus are
+ * idle on an APIC SMP system that does not have reliable APIC reprogramming
+ * with the PIT disabled.
+ */
+static void reprogram_pit_handler(void)
+{
+ unsigned long skip = dyn_tick->tick - jiffies;
+
+ if (skip > PIT_MAX_SKIP)
+ skip = PIT_MAX_SKIP;
+ reprogram_pit_timer(skip);
+}
+
+/*
+ * This reprograms the pit to maximum skips when calibrating APIC reprogramming
+ * As it will often delay the pit longer than APIC is skipping it is a good way
+ * to see if APIC timers work on their own.
+ */
+static void reprogram_max_pit(void)
+{
+ reprogram_pit_timer(PIT_MAX_SKIP);
+}
+
+static inline int null_enable(void)
+{
+ return 0;
+}
+
+static inline void null_pit_handler(void)
+{
+}
+
+static void do_dyn_tick_interrupt(struct pt_regs *regs);
+
+struct arch_dyn_handler arch_handler = {
+ .idle_pit_handler = &null_pit_handler,
+ .busy_pit_handler = &null_pit_handler,
+ .do_dyn_interrupt = &do_dyn_tick_interrupt,
+ .pit_handler = PIT_UP_SKIP,
+};
+
+static void arch_all_cpus_idle(int __unused)
+{
+ arch_handler.idle_pit_handler();
+}
+
+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 = &null_enable,
+ .arch_disable = &null_enable,
+};
+
+struct dyn_tick_timer *dyn_tick = &arch_dyn_tick;
+
+static inline void show_limits(void)
+{
+ printk(KERN_INFO "dyn-tick: Maximum ticks to skip limited to %i\n",
+ dyn_tick->max_skip);
+}
+
+static inline void set_pit_limits(void)
+{
+ set_dyn_tick_limits(PIT_MAX_SKIP, 0);
+}
+
+int __init dyn_tick_arch_init(void)
+{
+ if (arch_handler.pit_handler == PIT_UP_SKIP) {
+ set_pit_limits();
+ printk(KERN_INFO "dyn-tick: Using PIT reprogramming\n");
+ show_limits();
+ }
+
+ 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);
+
+/*
+ * 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.
+ */
+static inline int test_nohz_cpu(void)
+{
+ return __get_cpu_var(dyn_cpu).nohz_cpu;
+}
+
+static inline void clear_nohz_cpu(int cpu)
+{
+ __get_cpu_var(dyn_cpu).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);
+ arch_handler.busy_pit_handler();
+ 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();
+}
+
+static void select_apic_handler(void)
+{
+ switch (arch_handler.pit_handler) {
+ case PIT_SKIP:
+ printk(KERN_INFO
+ "dyn-tick: Using APIC reprogramming, skipping PIT when all cpus idle\n");
+ break;
+ case PIT_UP_SKIP:
+ printk(KERN_INFO
+ "dyn-tick: local APIC unreliable, using PIT reprogramming\n");
+ /*
+ * Reprogram the APIC timer to run quietly at the slowest rate
+ * possible to not upset the NMI watchdog.
+ */
+ apic_reprogram(dyn_tick->max_skip);
+ set_pit_limits();
+ break;
+ case PIT_DISABLE:
+ printk(KERN_INFO
+ "dyn-tick: Using APIC reprogramming, disabling PIT when all cpus idle\n");
+ break;
+ case PIT_OFF:
+ case PIT_UP_APIC:
+ printk(KERN_INFO
+ "dyn-tick: Using APIC reprogramming, turning PIT off entirely\n");
+ disable_pit_timer();
+ break;
+ }
+ arch_handler.do_dyn_interrupt = &do_dyn_tick_interrupt;
+ show_limits();
+}
+
+/*
+ * On SMP if there is a delay with PIT off for extended periods we can drop
+ * to disabling the pit timer only when all cpus are idle. If that fails we
+ * must move to pit reprogramming when all cpus are idle.
+ *
+ * On UP we either have PIT off with APIC reprogramming or use PIT
+ * reprogramming. Most only do the latter reliably.
+ */
+static void select_handler(void)
+{
+ switch (arch_handler.pit_handler) {
+ case PIT_SKIP:
+ dyn_tick->arch_reprogram = &apic_reprogram;
+ arch_handler.idle_pit_handler = &reprogram_pit_handler;
+ arch_handler.busy_pit_handler = &null_pit_handler;
+ break;
+ case PIT_UP_SKIP:
+ dyn_tick->arch_reprogram = &pit_reprogram;
+ arch_handler.idle_pit_handler = &null_pit_handler;
+ arch_handler.busy_pit_handler = &null_pit_handler;
+ select_apic_handler();
+ break;
+ case PIT_DISABLE:
+ dyn_tick->arch_reprogram = &apic_reprogram;
+ arch_handler.idle_pit_handler = &disable_pit_timer;
+ arch_handler.busy_pit_handler = &enable_pit_timer;
+ break;
+ case PIT_OFF:
+ case PIT_UP_APIC:
+ dyn_tick->arch_reprogram = &apic_reprogram;
+ arch_handler.idle_pit_handler = &null_pit_handler;
+ arch_handler.busy_pit_handler = &null_pit_handler;
+ break;
+ }
+}
+
+/*
+ * Select the next most suitable handler based on the previous handler.
+ */
+static void failed_pit_handler(void)
+{
+ switch (arch_handler.pit_handler) {
+ case PIT_SKIP:
+ case PIT_UP_SKIP:
+ return;
+ case PIT_DISABLE:
+ arch_handler.pit_handler = PIT_SKIP;
+ break;
+ case PIT_OFF:
+ arch_handler.pit_handler = PIT_DISABLE;
+ break;
+ case PIT_UP_APIC:
+ arch_handler.pit_handler = PIT_UP_SKIP;
+ break;
+ }
+ select_handler();
+}
+
+/*
+ * This function is used instead of do_dyn_tick_interrupt to determine what
+ * we need to do with the pit timer. We may be able to disable it completely,
+ * disable it only when all cpus are idle or have to drop APIC reprogramming
+ * entirely.
+ */
+static void apic_calibrate_interrupt(struct pt_regs *regs)
+{
+ static int count = 0;
+ int cpu = smp_processor_id();
+
+ write_seqlock(&xtime_lock);
+ spin_lock(&dyn_tick->lock);
+ count++;
+
+ 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);
+ arch_handler.busy_pit_handler();
+ /*
+ * Here we test to see that we skipped only as much as APIC
+ * reprogramming specified and if we skipped more it displays
+ * failure without PIT - very common.
+ */
+ if (lost > __get_cpu_var(dyn_cpu).skip + 2)
+ failed_pit_handler();
+ kstat_cpu(cpu).cpustat.idle += (lost - 1);
+ }
+ clear_nohz_cpu(cpu);
+
+ /*
+ * We let this run till 1000 hardware interrupts are generated while
+ * the cpu is idle to get a reasonable picture of APIC performance
+ */
+ if (count > 1000)
+ select_apic_handler();
+ 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();
+}
+
+void __init setup_dyn_tick_use_apic(unsigned int calibration_result)
+{
+ if (calibration_result) {
+ arch_handler.pit_handler = select_pit_handler();
+ select_handler();
+ arch_handler.idle_pit_handler = &reprogram_max_pit;
+ arch_handler.do_dyn_interrupt = &apic_calibrate_interrupt;
+ return;
+ }
+}
+
+inline void dyn_tick_interrupt(struct pt_regs *regs)
+{
+ if (!test_nohz_cpu())
+ return;
+ arch_handler.do_dyn_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 - pmtmr failed: ACPI disabled?\n",
+ cur_timer->name);
+}
+
+inline void idle_reprogram_timer(void)
+{
+ local_irq_disable();
+ if (!need_resched())
+ timer_dyn_reprogram();
+ local_irq_enable();
+}
Index: 2.6.15-rc7/arch/i386/kernel/io_apic.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/io_apic.c 2005-12-25 00:02:36.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/io_apic.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@

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 @@
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 @@
* 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 @@
#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: 2.6.15-rc7/arch/i386/kernel/irq.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/irq.c 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/irq.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@
}
#endif

+ dyn_tick_interrupt(regs);
+
#ifdef CONFIG_4KSTACKS

curctx = (union irq_ctx *) current_thread_info();
Index: 2.6.15-rc7/arch/i386/kernel/Makefile
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/Makefile 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/arch/i386/kernel/Makefile 2005-12-25 10:59:58.000000000 -0500
@@ -32,6 +32,7 @@
obj-y += sysenter.o vsyscall.o
obj-$(CONFIG_ACPI_SRAT) += srat.o
obj-$(CONFIG_HPET_TIMER) += time_hpet.o
+obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick.o
obj-$(CONFIG_EFI) += efi.o efi_stub.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o

Index: 2.6.15-rc7/arch/i386/kernel/process.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/process.c 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/process.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@
play_dead();

__get_cpu_var(irq_stat).idle_timestamp = jiffies;
+ idle_reprogram_timer();
+
idle();
}
preempt_enable_no_resched();
Index: 2.6.15-rc7/arch/i386/kernel/smp.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/smp.c 2005-12-25 00:02:36.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/smp.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@
{
unsigned long cpu;

+ dyn_tick_interrupt(regs);
+
cpu = get_cpu();

if (!cpu_isset(cpu, flush_cpumask))
@@ -600,6 +604,8 @@
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 @@
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: 2.6.15-rc7/arch/i386/kernel/time.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/time.c 2005-12-25 00:02:36.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/time.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@
* 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 @@
}
#endif

- do_timer_interrupt_hook(regs);
+ if (!dyn_tick_enabled() || lost)
+ do_timer_interrupt_hook(regs);

if (MCA_bus) {
@@ -288,6 +291,8 @@
*/
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 @@
*/
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;
@@ -430,7 +435,7 @@

/* XXX this driverfs stuff should probably go elsewhere later -john */
-static struct sys_device device_timer = {
+struct sys_device device_timer = {
.id = 0,
.cls = &timer_sysclass,
};
@@ -486,5 +491,7 @@
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: 2.6.15-rc7/arch/i386/kernel/timers/timer_pit.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/timers/timer_pit.c 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/timers/timer_pit.c 2005-12-25 10:59:58.000000000 -0500
@@ -32,9 +32,10 @@
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 @@
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: 2.6.15-rc7/arch/i386/kernel/timers/timer_pm.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/timers/timer_pm.c 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/arch/i386/kernel/timers/timer_pm.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@
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 @@
* 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 @@
/* 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 @@
/* 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 @@
now = read_pmtmr();
delta = (now - offset)&ACPI_PM_MASK;

- return (unsigned long) offset_delay + cyc2us(delta);
+ return (unsigned long) cyc2us(delta + offset_delay);
}

Index: 2.6.15-rc7/arch/i386/kernel/timers/timer_tsc.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/timers/timer_tsc.c 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/timers/timer_tsc.c 2005-12-25 10:59:58.000000000 -0500
@@ -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 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 @@
} 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 @@
/* 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 @@
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 @@
* 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 @@
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 @@
}
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 @@
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 @@
*/
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 @@
cpu_khz / 1000, cpu_khz % 1000);
}
set_cyc2ns_scale(cpu_khz);
+ set_dyn_tick_limits((0xFFFFFFFF / (cpu_khz * 1000)) *
+ HZ, 0);
return 0;
}
}
Index: 2.6.15-rc7/include/asm-i386/apic.h
===================================================================
--- 2.6.15-rc7.orig/include/asm-i386/apic.h 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/include/asm-i386/apic.h 2005-12-25 10:59:58.000000000 -0500
@@ -121,6 +121,7 @@
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 @@

#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: 2.6.15-rc7/include/asm-i386/dyn-tick.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6.15-rc7/include/asm-i386/dyn-tick.h 2005-12-25 10:59:58.000000000 -0500
@@ -0,0 +1,76 @@
+/*
+ * linux/include/asm-i386/dyn-tick.h
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ * Rewritten by Con Kolivas <kernel@xxxxxxxxxxx>
+ *
+ * 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 void __init setup_dyn_tick_use_apic(unsigned int calibration_result);
+extern void __init dyn_tick_time_init(struct timer_opts *cur_timer);
+
+#define PIT_MAX_SKIP (0xffff / (LATCH))
+
+enum pit_handler {
+ PIT_SKIP,
+ PIT_UP_SKIP,
+ PIT_DISABLE,
+ PIT_OFF,
+ PIT_UP_APIC,
+};
+
+struct arch_dyn_handler {
+ void (*idle_pit_handler)(void);
+ void (*busy_pit_handler)(void);
+ void (*do_dyn_interrupt)(struct pt_regs *regs);
+ enum pit_handler pit_handler;
+};
+
+extern struct arch_dyn_handler arch_handler;
+
+#ifdef CONFIG_SMP
+static inline enum pit_handler select_pit_handler(void)
+{
+ return PIT_OFF;
+}
+#else /* CONFIG_SMP */
+static inline enum pit_handler select_pit_handler(void)
+{
+ return PIT_UP_APIC;
+}
+#endif
+
+#else /* CONFIG_NO_IDLE_HZ */
+static inline void idle_reprogram_timer(void)
+{
+}
+
+static inline void dyn_tick_interrupt(struct pt_regs *regs)
+{
+}
+
+static inline void 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: 2.6.15-rc7/include/asm-i386/timer.h
===================================================================
--- 2.6.15-rc7.orig/include/asm-i386/timer.h 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/include/asm-i386/timer.h 2005-12-25 10:59:58.000000000 -0500
@@ -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 @@
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 @@
#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: 2.6.15-rc7/arch/i386/kernel/timers/timer_cyclone.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/timers/timer_cyclone.c 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/arch/i386/kernel/timers/timer_cyclone.c 2005-12-25 10:59:58.000000000 -0500
@@ -45,7 +45,7 @@
} 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 @@
*/
if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ))
jiffies_64++;
+
+ return lost;
}

static unsigned long get_offset_cyclone(void)
Index: 2.6.15-rc7/arch/i386/kernel/timers/timer_hpet.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/timers/timer_hpet.c 2005-12-25 00:01:21.000000000 -0500
+++ 2.6.15-rc7/arch/i386/kernel/timers/timer_hpet.c 2005-12-25 10:59:58.000000000 -0500
@@ -101,7 +101,7 @@
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 @@
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: 2.6.15-rc7/arch/i386/kernel/timers/timer_none.c
===================================================================
--- 2.6.15-rc7.orig/arch/i386/kernel/timers/timer_none.c 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/arch/i386/kernel/timers/timer_none.c 2005-12-25 10:59:59.000000000 -0500
@@ -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: 2.6.15-rc7/kernel/timer_top.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ 2.6.15-rc7/kernel/timer_top.c 2005-12-25 10:59:59.000000000 -0500
@@ -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 <d.pensator@xxxxxxxxx>
+ *
+ * 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: 2.6.15-rc7/lib/Kconfig.debug
===================================================================
--- 2.6.15-rc7.orig/lib/Kconfig.debug 2005-12-25 00:01:50.000000000 -0500
+++ 2.6.15-rc7/lib/Kconfig.debug 2005-12-25 10:59:59.000000000 -0500
@@ -77,6 +77,19 @@
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: 2.6.15-rc7/drivers/acpi/processor_idle.c
===================================================================
--- 2.6.15-rc7.orig/drivers/acpi/processor_idle.c 2005-12-25 00:01:32.000000000 -0500
+++ 2.6.15-rc7/drivers/acpi/processor_idle.c 2005-12-25 11:03:54.000000000 -0500
@@ -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 @@
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 @@
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
@@ -267,13 +270,61 @@
* 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;
}
}

+ /*
+ * 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
/*
* Check for P_LVL2_UP flag before entering C2 and above on
@@ -285,8 +336,6 @@
cx = &pr->power.states[ACPI_STATE_C1];
#endif

- cx->usage++;
-
/*
* Sleep:
* ------
@@ -384,9 +433,22 @@
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--;
+
#ifdef CONFIG_HOTPLUG_CPU
/* Don't do promotion/demotion */
if ((cx->type == ACPI_STATE_C1) && (num_online_cpus() > 1) &&
@@ -998,9 +1060,10 @@
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: 2.6.15-rc7/include/acpi/processor.h
===================================================================
--- 2.6.15-rc7.orig/include/acpi/processor.h 2005-10-27 20:02:08.000000000 -0400
+++ 2.6.15-rc7/include/acpi/processor.h 2005-12-25 10:59:59.000000000 -0500
@@ -51,6 +51,7 @@
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 @@
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];

Index: 2.6.15-rc7/drivers/input/serio/i8042.h
===================================================================
--- 2.6.15-rc7.orig/drivers/input/serio/i8042.h 2005-12-25 00:01:35.000000000 -0500
+++ 2.6.15-rc7/drivers/input/serio/i8042.h 2005-12-25 10:59:59.000000000 -0500
@@ -44,7 +44,7 @@
* polling.
*/

-#define I8042_POLL_PERIOD HZ/20
+#define I8042_POLL_PERIOD HZ/5

/*
* Status register bits.

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