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Subject[PATCH 1/3] dynticks - implement no idle hz for x86
Date
Ok I've resynced all the patches with 2.6.13-mm1, made some cleanups and minor 
modifications. As pm timer is the only supported timer for dynticks I've also
made it depend on it.

A rollup patch against 2.6.13-mm1 is here:

http://ck.kolivas.org/patches/dyn-ticks/2.6.13-mm1-dtck1.patch

also available in the dyn-ticks directory are the older patches and these
split out patches posted here.

Cheers,
Con
---

This patch implements the no idle hz feature aka dynamic ticks for
i386 architecture. Work originally by Tony Lindgren <tony@atomide.com>
and Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.

Modified for better smp scalability and accurate time by Srivatsa Vaddagiri
<vatsa@in.ibm.com>, with minor cleanups and modifications by Con Kolivas.

Signed-off-By: Con Kolivas <kernel@kolivas.org>

Index: linux-2.6.13-mm1/arch/i386/defconfig
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/defconfig 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/defconfig 2005-09-02 23:57:33.000000000 +1000
@@ -91,6 +91,7 @@ CONFIG_X86_INTEL_USERCOPY=y
CONFIG_X86_USE_PPRO_CHECKSUM=y
# CONFIG_HPET_TIMER is not set
# CONFIG_HPET_EMULATE_RTC is not set
+# CONFIG_NO_IDLE_HZ is not set
CONFIG_SMP=y
CONFIG_NR_CPUS=8
CONFIG_SCHED_SMT=y
Index: linux-2.6.13-mm1/arch/i386/Kconfig
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/Kconfig 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/Kconfig 2005-09-02 23:57:33.000000000 +1000
@@ -462,6 +462,21 @@ config HPET_EMULATE_RTC
depends on HPET_TIMER && RTC=y
default y

+config NO_IDLE_HZ
+ bool "Dynamic Tick Timer - Skip timer ticks during idle"
+ depends on EXPERIMENTAL && 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 supported timer is ACPI PM
+ timer. TSC and HPET timers are 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 SMP
bool "Symmetric multi-processing support"
---help---
Index: linux-2.6.13-mm1/arch/i386/kernel/apic.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/apic.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/apic.c 2005-09-02 23:57:33.000000000 +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>
@@ -927,6 +928,8 @@ void (*wait_timer_tick)(void) __devinitd

#define APIC_DIVISOR 16

+static u32 apic_timer_val;
+
static void __setup_APIC_LVTT(unsigned int clocks)
{
unsigned int lvtt_value, tmp_value, ver;
@@ -945,7 +948,9 @@ static void __setup_APIC_LVTT(unsigned i
& ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE))
| APIC_TDR_DIV_16);

- apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
+ apic_timer_val = clocks / APIC_DIVISOR;
+
+ apic_write_around(APIC_TMICT, apic_timer_val);
}

static void __devinit setup_APIC_timer(unsigned int clocks)
@@ -964,6 +969,21 @@ static void __devinit setup_APIC_timer(u
local_irq_restore(flags);
}

+/* Used by NO_IDLE_HZ to skip ticks on idle CPUs */
+void reprogram_apic_timer(unsigned int count)
+{
+ unsigned long flags;
+
+ /*
+ * FIXME: Make count more accurate. Otherwise can lead
+ * to latencies of upto 1 jiffy in servicing timers.
+ */
+ 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
@@ -1058,6 +1078,10 @@ void __init setup_boot_APIC_clock(void)
*/
setup_APIC_timer(calibration_result);

+ setup_dyn_tick_use_apic(calibration_result);
+ set_dyn_tick_max_skip((0xFFFFFFFF / calibration_result) *
+ APIC_DIVISOR);
+
local_irq_enable();
}

@@ -1196,6 +1220,9 @@ fastcall void smp_apic_timer_interrupt(s
* interrupt lock, which is the WrongThing (tm) to do.
*/
irq_enter();
+
+ dyn_tick_interrupt(LOCAL_TIMER_VECTOR, regs);
+
smp_local_timer_interrupt(regs);
irq_exit();
}
@@ -1208,6 +1235,9 @@ fastcall void smp_spurious_interrupt(str
unsigned long v;

irq_enter();
+
+ dyn_tick_interrupt(SPURIOUS_APIC_VECTOR, regs);
+
/*
* Check if this really is a spurious interrupt and ACK it
* if it is a vectored one. Just in case...
@@ -1232,6 +1262,9 @@ fastcall void smp_error_interrupt(struct
unsigned long v, v1;

irq_enter();
+
+ dyn_tick_interrupt(ERROR_APIC_VECTOR, regs);
+
/* First tickle the hardware, only then report what went on. -- REW */
v = apic_read(APIC_ESR);
apic_write(APIC_ESR, 0);
Index: linux-2.6.13-mm1/arch/i386/kernel/dyn-tick.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/dyn-tick.c 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-mm1/arch/i386/kernel/dyn-tick.c 2005-09-03 01:11:54.000000000 +1000
@@ -0,0 +1,132 @@
+/*
+ * 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 <linux/timer.h>
+#include <linux/irq.h>
+#include <asm/apic.h>
+
+static void arch_reprogram_timer(unsigned long jif_next)
+{
+ unsigned int skip = jif_next - jiffies;
+
+ if (cpu_has_local_apic())
+ reprogram_apic_timer(skip);
+ else
+ reprogram_pit_timer(skip);
+
+ /* Fixme: Disable NMI Watchdog */
+}
+
+static void arch_all_cpus_idle(int how_long)
+{
+ if (cpu_has_local_apic())
+ disable_pit_timer();
+}
+
+static struct dyn_tick_timer arch_dyn_tick_timer = {
+ .arch_reprogram_timer = &arch_reprogram_timer,
+ .arch_all_cpus_idle = &arch_all_cpus_idle,
+};
+
+int __init dyn_tick_arch_init(void)
+{
+ if (!cpu_has_local_apic())
+ set_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);
+
+ return 0;
+}
+
+static 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);
+
+/* Functions that need blank prototypes for !CONFIG_NO_IDLE_HZ below here */
+void setup_dyn_tick_use_apic(unsigned int calibration_result)
+{
+ if (calibration_result)
+ dyn_tick->arch_state |= DYN_TICK_APICABLE;
+ else {
+ dyn_tick->arch_state &= ~DYN_TICK_APICABLE;
+ printk(KERN_INFO "dyn-tick: Cannot use local APIC\n");
+ }
+}
+
+void dyn_tick_interrupt(int irq, struct pt_regs *regs)
+{
+ int all_were_sleeping = 0;
+ int cpu = smp_processor_id();
+
+ if (!cpu_isset(cpu, nohz_cpu_mask))
+ return;
+
+ spin_lock(&dyn_tick_lock);
+
+ if (cpus_equal(nohz_cpu_mask, cpu_online_map))
+ all_were_sleeping = 1;
+ cpu_clear(cpu, nohz_cpu_mask);
+
+ if (all_were_sleeping) {
+ /* Recover jiffies */
+ cur_timer->mark_offset();
+ if (cpu_has_local_apic())
+ enable_pit_timer();
+ }
+
+ spin_unlock(&dyn_tick_lock);
+
+ if (cpu_has_local_apic())
+ /* Fixme: Needs to be more accurate */
+ reprogram_apic_timer(1);
+ else
+ reprogram_pit_timer(1);
+
+ conditional_run_local_timers();
+
+ /* Fixme: Enable NMI watchdog */
+}
+
+
+void dyn_tick_time_init(struct timer_opts *cur_timer)
+{
+ spin_lock_init(&dyn_tick_lock);
+
+ if (strncmp(cur_timer->name, "pmtmr", 3) == 0) {
+ dyn_tick->state |= DYN_TICK_SUITABLE;
+ printk(KERN_INFO "dyn-tick: Found suitable timer: %s\n",
+ cur_timer->name);
+ } else
+ printk(KERN_ERR "dyn-tick: Cannot use timer %s\n",
+ cur_timer->name);
+}
+
+void idle_reprogram_timer(void)
+{
+ local_irq_disable();
+ if (!need_resched())
+ dyn_tick_reprogram_timer();
+ local_irq_enable();
+}
Index: linux-2.6.13-mm1/arch/i386/kernel/io_apic.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/io_apic.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/io_apic.c 2005-09-03 00:54:58.000000000 +1000
@@ -33,6 +33,7 @@
#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>
@@ -1159,15 +1160,19 @@ static inline void ioapic_register_intr(
if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
trigger == IOAPIC_LEVEL)
irq_desc[vector].handler = &ioapic_level_type;
- else
+ else if (vector)
irq_desc[vector].handler = &ioapic_edge_type;
+ else
+ irq_desc[vector].handler = IOAPIC_EDGE_TYPE_IRQ0;
set_intr_gate(vector, interrupt[vector]);
} else {
if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
trigger == IOAPIC_LEVEL)
irq_desc[irq].handler = &ioapic_level_type;
- else
+ else if (irq)
irq_desc[irq].handler = &ioapic_edge_type;
+ else
+ irq_desc[irq].handler = IOAPIC_EDGE_TYPE_IRQ0;
set_intr_gate(vector, interrupt[irq]);
}
}
@@ -1280,7 +1285,7 @@ static void __init setup_ExtINT_IRQ0_pin
* The timer IRQ doesn't have to know that behind the
* scene we have a 8259A-master in AEOI mode ...
*/
- irq_desc[0].handler = &ioapic_edge_type;
+ irq_desc[0].handler = IOAPIC_EDGE_TYPE_IRQ0;

/*
* Add it to the IO-APIC irq-routing table:
@@ -2015,6 +2020,20 @@ static struct hw_interrupt_type ioapic_l
#endif
};

+/* Needed to disable PIT interrupts when all CPUs sleep */
+struct hw_interrupt_type ioapic_edge_type_irq0 = {
+ .typename = "IO-APIC-edge-irq0",
+ .startup = startup_edge_ioapic,
+ .shutdown = shutdown_edge_ioapic,
+ .enable = unmask_IO_APIC_irq,
+ .disable = mask_IO_APIC_irq,
+ .ack = ack_edge_ioapic,
+ .end = end_edge_ioapic,
+#ifdef CONFIG_SMP
+ .set_affinity = set_ioapic_affinity,
+#endif
+};
+
static inline void init_IO_APIC_traps(void)
{
int irq;
Index: linux-2.6.13-mm1/arch/i386/kernel/irq.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/irq.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/irq.c 2005-09-02 23:57:33.000000000 +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);
@@ -79,6 +80,8 @@ 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-mm1/arch/i386/kernel/Makefile
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/Makefile 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/Makefile 2005-09-02 23:57:33.000000000 +1000
@@ -33,6 +33,7 @@ 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-mm1/arch/i386/kernel/process.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/process.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/process.c 2005-09-02 23:57:33.000000000 +1000
@@ -40,6 +40,7 @@
#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>
@@ -201,6 +202,8 @@ void cpu_idle(void)
if (cpu_is_offline(cpu))
play_dead();

+ idle_reprogram_timer();
+
__get_cpu_var(irq_stat).idle_timestamp = jiffies;
idle();
}
Index: linux-2.6.13-mm1/arch/i386/kernel/smp.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/smp.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/smp.c 2005-09-02 23:57:33.000000000 +1000
@@ -21,6 +21,7 @@
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <linux/module.h>
+#include <linux/dyn-tick.h>

#include <asm/nmi.h>
#include <asm/mtrr.h>
@@ -315,6 +316,8 @@ fastcall void smp_invalidate_interrupt(s
{
unsigned long cpu;

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

if (!cpu_isset(cpu, flush_cpumask))
@@ -695,6 +698,8 @@ void smp_send_stop(void)
fastcall void smp_reschedule_interrupt(struct pt_regs *regs)
{
ack_APIC_irq();
+
+ dyn_tick_interrupt(RESCHEDULE_VECTOR, regs);
}

fastcall void smp_call_function_interrupt(struct pt_regs *regs)
@@ -704,6 +709,9 @@ fastcall void smp_call_function_interrup
int wait = call_data->wait;

ack_APIC_irq();
+
+ dyn_tick_interrupt(CALL_FUNCTION_VECTOR, regs);
+
/*
* Notify initiating CPU that I've grabbed the data and am
* about to execute the function
Index: linux-2.6.13-mm1/arch/i386/kernel/time.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/time.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/time.c 2005-09-03 01:11:54.000000000 +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>
@@ -429,7 +430,7 @@ static struct sysdev_class timer_sysclas


/* XXX this driverfs stuff should probably go elsewhere later -john */
-static struct sys_device device_timer = {
+struct sys_device device_timer = {
.id = 0,
.cls = &timer_sysclass,
};
@@ -485,5 +486,7 @@ void __init time_init(void)
cur_timer = select_timer();
printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);

+ dyn_tick_time_init(cur_timer);
+
time_init_hook();
}
Index: linux-2.6.13-mm1/arch/i386/kernel/timers/timer_pit.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/timers/timer_pit.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/timers/timer_pit.c 2005-09-03 01:11:54.000000000 +1000
@@ -148,6 +148,38 @@ static unsigned long get_offset_pit(void
return count;
}

+void disable_pit_timer(void)
+{
+ irq_desc[0].handler->disable(0);
+}
+
+void enable_pit_timer(void)
+{
+ irq_desc[0].handler->enable(0);
+}
+
+/*
+ * Reprograms the next timer interrupt
+ * PIT timer reprogramming code taken from APM code.
+ * Note that PIT timer is a 16-bit timer, which allows max
+ * skip of only few seconds.
+ */
+void reprogram_pit_timer(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-mm1/arch/i386/kernel/timers/timer_pm.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/timers/timer_pm.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/timers/timer_pm.c 2005-09-03 01:11:55.000000000 +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>
@@ -128,6 +129,7 @@ pm_good:
return -ENODEV;

init_cpu_khz();
+ set_dyn_tick_max_skip((0xFFFFFF / (286 * 1000000)) * 1024 * HZ);
return 0;
}

Index: linux-2.6.13-mm1/arch/i386/kernel/timers/timer_tsc.c
===================================================================
--- linux-2.6.13-mm1.orig/arch/i386/kernel/timers/timer_tsc.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/arch/i386/kernel/timers/timer_tsc.c 2005-09-03 01:11:54.000000000 +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>
@@ -32,8 +33,6 @@ static unsigned long hpet_last;
static struct timer_opts timer_tsc;
#endif

-static inline void cpufreq_delayed_get(void);
-
int tsc_disable __devinitdata = 0;

static int use_tsc;
@@ -166,10 +165,19 @@ 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 +205,7 @@ 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 */
@@ -237,7 +243,7 @@ static void handle_cpufreq_delayed_get(v
* to verify the CPU frequency the timing core thinks the CPU is running
* at is still correct.
*/
-static inline void cpufreq_delayed_get(void)
+void cpufreq_delayed_get(void)
{
if (cpufreq_init && !cpufreq_delayed_issched) {
cpufreq_delayed_issched = 1;
@@ -316,7 +322,7 @@ static int __init cpufreq_tsc(void)
core_initcall(cpufreq_tsc);

#else /* CONFIG_CPU_FREQ */
-static inline void cpufreq_delayed_get(void) { return; }
+void cpufreq_delayed_get(void) { return; }
#endif

int recalibrate_cpu_khz(void)
@@ -346,8 +352,8 @@ static void mark_offset_tsc(void)
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;
+ int lost_count = 0;

write_seqlock(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
@@ -417,26 +423,11 @@ static void mark_offset_tsc(void)
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();
+ tsc_sanity_check(&lost_count);
} 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 */
@@ -537,6 +528,9 @@ static int __init init_tsc(char* overrid
cpu_khz / 1000, cpu_khz % 1000);
}
set_cyc2ns_scale(cpu_khz/1000);
+ /* FIXME: Make use of 64-bit TSC to recover jiffies */
+ set_dyn_tick_max_skip((0xFFFFFFFF /
+ (cpu_khz * 1000)) * HZ);
return 0;
}
}
Index: linux-2.6.13-mm1/drivers/acpi/Kconfig
===================================================================
--- linux-2.6.13-mm1.orig/drivers/acpi/Kconfig 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/drivers/acpi/Kconfig 2005-09-02 23:57:33.000000000 +1000
@@ -302,6 +302,8 @@ config X86_PM_TIMER
like aggressive processor idling, throttling, frequency and/or
voltage scaling, unlike the commonly used Time Stamp Counter
(TSC) timing source.
+
+ This timer is required 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
Index: linux-2.6.13-mm1/include/asm-i386/apic.h
===================================================================
--- linux-2.6.13-mm1.orig/include/asm-i386/apic.h 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/include/asm-i386/apic.h 2005-09-02 23:57:33.000000000 +1000
@@ -121,6 +121,7 @@ extern void nmi_watchdog_tick (struct pt
extern int APIC_init_uniprocessor (void);
extern void disable_APIC_timer(void);
extern void enable_APIC_timer(void);
+extern void reprogram_apic_timer(unsigned int count);

extern void enable_NMI_through_LVT0 (void * dummy);

@@ -132,6 +133,7 @@ extern unsigned int nmi_watchdog;

#else /* !CONFIG_X86_LOCAL_APIC */
static inline void lapic_shutdown(void) { }
+static inline void reprogram_apic_timer(unsigned int count) { }

#endif /* !CONFIG_X86_LOCAL_APIC */

Index: linux-2.6.13-mm1/include/asm-i386/dyn-tick.h
===================================================================
--- linux-2.6.13-mm1.orig/include/asm-i386/dyn-tick.h 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-mm1/include/asm-i386/dyn-tick.h 2005-09-03 01:12:03.000000000 +1000
@@ -0,0 +1,91 @@
+/*
+ * 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>
+#include <asm/timer.h>
+
+extern void cpufreq_delayed_get(void);
+
+#ifdef CONFIG_NO_IDLE_HZ
+extern void setup_dyn_tick_use_apic(unsigned int calibration_result);
+extern void dyn_tick_interrupt(int irq, struct pt_regs *regs);
+extern void dyn_tick_time_init(struct timer_opts *cur_timer);
+
+#define DYN_TICK_APICABLE (1 << 0)
+
+#if (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC))
+static inline int cpu_has_local_apic(void)
+{
+ return (dyn_tick->arch_state & DYN_TICK_APICABLE);
+}
+
+#else /* (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC)) */
+static inline int cpu_has_local_apic(void)
+{
+ return 0;
+}
+#endif /* (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC)) */
+
+#define IOAPIC_EDGE_TYPE_IRQ0 (&(ioapic_edge_type_irq0))
+
+extern struct hw_interrupt_type ioapic_edge_type_irq0;
+
+extern void idle_reprogram_timer(void);
+
+static inline void tsc_sanity_check(int *lost_count)
+{
+}
+
+#else /* CONFIG_NO_IDLE_HZ */
+
+#define IOAPIC_EDGE_TYPE_IRQ0 (&(ioapic_edge_type))
+
+static inline void setup_dyn_tick_use_apic(unsigned int calibration_result)
+{
+}
+
+static inline void dyn_tick_interrupt(int irq, struct pt_regs *regs)
+{
+}
+
+static inline void dyn_tick_time_init(struct timer_opts *cur_timer)
+{
+}
+
+static inline void idle_reprogram_timer(void)
+{
+}
+
+static inline void tsc_sanity_check(int *lost_count)
+{
+ /* 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();
+}
+#endif /* CONFIG_NO_IDLE_HZ */
+
+#endif /* _ASM_I386_DYN_TICK_H_ */
Index: linux-2.6.13-mm1/include/asm-i386/timer.h
===================================================================
--- linux-2.6.13-mm1.orig/include/asm-i386/timer.h 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/include/asm-i386/timer.h 2005-09-03 01:11:54.000000000 +1000
@@ -38,6 +38,9 @@ struct init_timer_opts {
extern struct timer_opts* __init select_timer(void);
extern void clock_fallback(void);
void setup_pit_timer(void);
+extern void disable_pit_timer(void);
+extern void enable_pit_timer(void);
+extern void reprogram_pit_timer(int jiffies_to_skip);

/* Modifiers for buggy PIT handling */

Index: linux-2.6.13-mm1/include/linux/dyn-tick.h
===================================================================
--- linux-2.6.13-mm1.orig/include/linux/dyn-tick.h 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-mm1/include/linux/dyn-tick.h 2005-09-03 01:00:51.000000000 +1000
@@ -0,0 +1,70 @@
+/*
+ * 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_ENABLED (1 << 1)
+#define DYN_TICK_SUITABLE (1 << 0)
+
+#define DYN_TICK_MIN_SKIP 2
+
+struct dyn_tick_state {
+ unsigned short state; /* Current state */
+ unsigned short arch_state; /* Arch-specific state */
+ unsigned int max_skip; /* Max number of ticks to skip */
+};
+
+struct dyn_tick_timer {
+ int (*arch_init) (void);
+ void (*arch_enable) (void);
+ void (*arch_disable) (void);
+ void (*arch_reprogram_timer) (unsigned long);
+ void (*arch_all_cpus_idle) (int);
+};
+
+extern struct dyn_tick_state *dyn_tick;
+extern spinlock_t dyn_tick_lock;
+extern void dyn_tick_register(struct dyn_tick_timer *new_timer);
+
+#ifdef CONFIG_NO_IDLE_HZ
+extern unsigned int dyn_tick_reprogram_timer(void);
+extern void set_dyn_tick_max_skip(unsigned int max_skip);
+
+static inline int dyn_tick_enabled(void)
+{
+ return (dyn_tick->state & DYN_TICK_ENABLED);
+}
+
+#else /* CONFIG_NO_IDLE_HZ */
+static inline unsigned int dyn_tick_reprogram_timer(void)
+{
+ return 0;
+}
+
+static inline void set_dyn_tick_max_skip(unsigned int max_skip)
+{
+}
+
+static inline int dyn_tick_enabled(void)
+{
+ return 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-mm1/include/linux/timer.h
===================================================================
--- linux-2.6.13-mm1.orig/include/linux/timer.h 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/include/linux/timer.h 2005-09-03 00:22:21.000000000 +1000
@@ -91,6 +91,7 @@ static inline void add_timer(struct time

extern void init_timers(void);
extern void run_local_timers(void);
+extern void conditional_run_local_timers(void);
extern void it_real_fn(unsigned long);

#endif
Index: linux-2.6.13-mm1/kernel/dyn-tick.c
===================================================================
--- linux-2.6.13-mm1.orig/kernel/dyn-tick.c 2005-01-12 16:19:45.000000000 +1100
+++ linux-2.6.13-mm1/kernel/dyn-tick.c 2005-09-03 00:22:44.000000000 +1000
@@ -0,0 +1,222 @@
+/*
+ * 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 <linux/rcupdate.h>
+
+#define DYN_TICK_VERSION "050610-1"
+#define DYN_TICK_IS_SET(x) ((dyn_tick->state & (x)) == (x))
+
+static struct dyn_tick_state dyn_tick_state;
+struct dyn_tick_state *dyn_tick = &dyn_tick_state;
+static struct dyn_tick_timer *dyn_tick_cfg;
+spinlock_t dyn_tick_lock;
+
+/*
+ * Arch independent code needed to reprogram next timer interrupt.
+ * Gets called, with IRQs disabled, from cpu_idle() before entering idle loop.
+ */
+unsigned int dyn_tick_reprogram_timer(void)
+{
+ int cpu = smp_processor_id();
+ unsigned int delta;
+
+ if (!DYN_TICK_IS_SET(DYN_TICK_ENABLED))
+ return 0;
+
+ if (rcu_pending(cpu) || local_softirq_pending())
+ return 0;
+
+ /* Check if we can start skipping ticks */
+ 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;
+
+ spin_lock(&dyn_tick_lock);
+
+ dyn_tick_cfg->arch_reprogram_timer(jiffies + delta);
+
+ cpu_set(cpu, nohz_cpu_mask);
+ if (cpus_equal(nohz_cpu_mask, cpu_online_map))
+ /* Fixme: idle_time needs to be computed */
+ dyn_tick_cfg->arch_all_cpus_idle(idle_time);
+
+ spin_unlock(&dyn_tick_lock);
+
+ } else
+ delta = 0;
+
+ write_sequnlock(&xtime_lock);
+
+ return delta;
+}
+
+void set_dyn_tick_max_skip(unsigned int max_skip)
+{
+ if (!dyn_tick->max_skip || max_skip < dyn_tick->max_skip)
+ dyn_tick->max_skip = max_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;
+
+/*
+ * dyntick=[disable]
+ */
+static int __init dyntick_setup(char *options)
+{
+ if (!options)
+ return 0;
+
+ if (!strncmp(options, "disable", 6))
+ dyntick_autoenable = 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",
+ DYN_TICK_IS_SET(DYN_TICK_SUITABLE),
+ DYN_TICK_IS_SET(DYN_TICK_ENABLED));
+}
+
+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 SYSDEV_ATTR(state, 0444, show_dyn_tick_state, NULL);
+static SYSDEV_ATTR(enable, 0644, show_dyn_tick_enable,
+ set_dyn_tick_enable);
+
+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;
+ error = sysdev_create_file(&device_dyn_tick, &attr_enable);
+
+out:
+ return error;
+}
+
+device_initcall(init_dyn_tick_sysfs);
+
+/*
+ * ---------------------------------------------------------------------------
+ * Init functions
+ * ---------------------------------------------------------------------------
+ */
+
+/*
+ * 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 ((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-mm1/kernel/Makefile
===================================================================
--- linux-2.6.13-mm1.orig/kernel/Makefile 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/kernel/Makefile 2005-09-02 23:57:33.000000000 +1000
@@ -32,6 +32,7 @@ obj-$(CONFIG_DETECT_SOFTLOCKUP) += softl
obj-$(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
Index: linux-2.6.13-mm1/kernel/timer.c
===================================================================
--- linux-2.6.13-mm1.orig/kernel/timer.c 2005-09-02 23:57:29.000000000 +1000
+++ linux-2.6.13-mm1/kernel/timer.c 2005-09-03 00:32:19.000000000 +1000
@@ -939,6 +939,13 @@ void run_local_timers(void)
}
}

+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!
\
 
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