Re: [PATCH] i386 no idle hz - aka dynticks v051118-1

From: Con Kolivas
Date: Sun Nov 20 2005 - 03:01:58 EST

On Fri, 18 Nov 2005 23:22, Con Kolivas wrote:
> So far this version seems to boot and run fine, but there are at least 2
> places in the kernel that need to be made aware of the fact they're running
> dynticks; the ondemand scaling governor and the bus mastering code (as
> pointed out by Tytso). Both don't realise the few ticks that have passed
> are quite some distance apart and overestimate the load grossly. They are
> not harmful, but lead to increase in power usage instead of a decrease. I
> have yet to investigate that code portion to see what needs to be done

After 2 days of uptime this patch did not show any instability nor time loss.
The only other issue that showed up was that per-process load is also
calculated incorrectly so I need to address that as well.

> The current patch is a series of 3 patches and a rollup and the split-out
> patches are all available here:
> http://ck.kolivas.org/patches/dyn-ticks/

And inlined again here again (unchanged) instead of attached.

Cheers,
Con


---

Index: linux-2.6.15-rc1-dt/arch/i386/Kconfig
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/Kconfig
+++ linux-2.6.15-rc1-dt/arch/i386/Kconfig
@@ -173,6 +173,22 @@ config HPET_EMULATE_RTC
depends on HPET_TIMER && RTC=y
default y

+config NO_IDLE_HZ
+ bool "Dynamic Tick Timer - Skip timer ticks during idle"
+ depends on EXPERIMENTAL
+ select X86_PM_TIMER
+ help
+ This option enables support for skipping timer ticks when the
+ processor is idle. During system load, timer is continuous.
+ This option saves power, as it allows the system to stay in
+ idle mode longer. Currently the only supported timer is ACPI PM
+ timer. TSC and HPET timers are 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-2.6.15-rc1-dt/arch/i386/defconfig
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/defconfig
+++ linux-2.6.15-rc1-dt/arch/i386/defconfig
@@ -91,6 +91,7 @@ CONFIG_X86_INTEL_USERCOPY=y
CONFIG_X86_USE_PPRO_CHECKSUM=y
# CONFIG_HPET_TIMER is not set
# CONFIG_HPET_EMULATE_RTC is not set
+# CONFIG_NO_IDLE_HZ is not set
CONFIG_SMP=y
CONFIG_NR_CPUS=8
CONFIG_SCHED_SMT=y
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/Makefile
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/Makefile
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_MODULES) += module.o
obj-y += sysenter.o vsyscall.o
obj-$(CONFIG_ACPI_SRAT) += srat.o
obj-$(CONFIG_HPET_TIMER) += time_hpet.o
+obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick.o
obj-$(CONFIG_EFI) += efi.o efi_stub.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o

Index: linux-2.6.15-rc1-dt/arch/i386/kernel/apic.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/apic.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/apic.c
@@ -26,6 +26,7 @@
#include <linux/kernel_stat.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
+#include <linux/dyn-tick.h>

#include <asm/atomic.h>
#include <asm/smp.h>
@@ -932,6 +933,9 @@ void (*wait_timer_tick)(void) __devinitd

#define APIC_DIVISOR 16

+static u32 apic_timer_val;
+#define APIC_TIMER_VAL ((apic_timer_val) / (HZ))
+
static void __setup_APIC_LVTT(unsigned int clocks)
{
unsigned int lvtt_value, tmp_value, ver;
@@ -950,7 +954,9 @@ static void __setup_APIC_LVTT(unsigned i
& ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE))
| APIC_TDR_DIV_16);

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

static void __devinit setup_APIC_timer(unsigned int clocks)
@@ -969,6 +975,17 @@ static void __devinit setup_APIC_timer(u
local_irq_restore(flags);
}

+/* Used by NO_IDLE_HZ to skip ticks on idle CPUs */
+void reprogram_apic_timer(unsigned long count)
+{
+ unsigned long flags;
+
+ count = count * apic_timer_val / HZ;
+ local_irq_save(flags);
+ apic_write_around(APIC_TMICT, count);
+ local_irq_restore(flags);
+}
+
/*
* In this function we calibrate APIC bus clocks to the external
* timer. Unfortunately we cannot use jiffies and the timer irq
@@ -1064,6 +1081,9 @@ 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_restore(flags);
}

@@ -1202,6 +1222,9 @@ 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();
}
@@ -1214,6 +1237,9 @@ 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...
@@ -1238,6 +1264,9 @@ 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-2.6.15-rc1-dt/arch/i386/kernel/dyn-tick.c
===================================================================
--- /dev/null
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/dyn-tick.c
@@ -0,0 +1,154 @@
+/*
+ * linux/arch/i386/kernel/dyn-tick.c
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ *
+ * 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 inline void reprogram_timer(unsigned long skip)
+{
+ if (cpu_has_local_apic())
+ reprogram_apic_timer(skip);
+ else
+ reprogram_pit_timer(skip);
+}
+
+static void arch_reprogram(unsigned long jif_next)
+{
+ unsigned long skip = jif_next - jiffies;
+
+ reprogram_timer(skip);
+ /* Fixme: Disable NMI Watchdog */
+}
+
+static void arch_all_cpus_idle(int how_long)
+{
+ if (cpu_has_local_apic())
+ disable_pit_timer();
+}
+
+static inline int arch_enable(void)
+{
+ return 0;
+}
+
+static inline int arch_disable(void)
+{
+ return 0;
+}
+
+static struct dyn_tick_timer arch_dyn_tick = {
+ .arch_reprogram = &arch_reprogram,
+ .arch_all_cpus_idle = &arch_all_cpus_idle,
+ .arch_enable = &arch_enable,
+ .arch_disable = &arch_disable,
+ .min_skip = DYN_TICK_MIN_SKIP,
+};
+
+struct dyn_tick_timer *dyn_tick = &arch_dyn_tick;
+spinlock_t *dyn_tick_lock = &arch_dyn_tick.lock;
+
+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",
+ arch_dyn_tick.max_skip);
+
+ return 0;
+}
+
+static int __init dyn_tick_init(void)
+{
+ arch_dyn_tick.arch_init = dyn_tick_arch_init;
+ dyn_tick_register(&arch_dyn_tick);
+
+ 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)
+ arch_dyn_tick.state |= DYN_TICK_APICABLE;
+ else {
+ arch_dyn_tick.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 */
+ if (irq) {
+ int lost;
+
+ lost = cur_timer->mark_offset();
+ if (lost)
+ do_timer(regs);
+ }
+ if (cpu_has_local_apic())
+ enable_pit_timer();
+ }
+
+ spin_unlock(dyn_tick_lock);
+
+ reprogram_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) {
+ arch_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())
+ timer_dyn_reprogram();
+ local_irq_enable();
+}
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/io_apic.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/io_apic.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/io_apic.c
@@ -32,6 +32,7 @@
#include <linux/acpi.h>
#include <linux/module.h>
#include <linux/sysdev.h>
+#include <linux/dyn-tick.h>

#include <asm/io.h>
#include <asm/smp.h>
@@ -1190,15 +1191,19 @@ static inline void ioapic_register_intr(
if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
trigger == IOAPIC_LEVEL)
irq_desc[vector].handler = &ioapic_level_type;
- else
+ else if (vector)
irq_desc[vector].handler = &ioapic_edge_type;
+ else
+ irq_desc[vector].handler = IOAPIC_EDGE_TYPE_IRQ0;
set_intr_gate(vector, interrupt[vector]);
} else {
if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
trigger == IOAPIC_LEVEL)
irq_desc[irq].handler = &ioapic_level_type;
- else
+ else if (irq)
irq_desc[irq].handler = &ioapic_edge_type;
+ else
+ irq_desc[irq].handler = IOAPIC_EDGE_TYPE_IRQ0;
set_intr_gate(vector, interrupt[irq]);
}
}
@@ -1311,7 +1316,7 @@ static void __init setup_ExtINT_IRQ0_pin
* The timer IRQ doesn't have to know that behind the
* scene we have a 8259A-master in AEOI mode ...
*/
- irq_desc[0].handler = &ioapic_edge_type;
+ irq_desc[0].handler = IOAPIC_EDGE_TYPE_IRQ0;

/*
* Add it to the IO-APIC irq-routing table:
@@ -2088,6 +2093,20 @@ 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-2.6.15-rc1-dt/arch/i386/kernel/irq.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/irq.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/irq.c
@@ -18,6 +18,7 @@
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/delay.h>
+#include <linux/dyn-tick.h>

DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_maxaligned_in_smp;
EXPORT_PER_CPU_SYMBOL(irq_stat);
@@ -76,6 +77,8 @@ fastcall unsigned int do_IRQ(struct pt_r
}
#endif

+ dyn_tick_interrupt(irq, regs);
+
#ifdef CONFIG_4KSTACKS

curctx = (union irq_ctx *) current_thread_info();
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/process.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/process.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/process.c
@@ -39,6 +39,7 @@
#include <linux/ptrace.h>
#include <linux/random.h>
#include <linux/kprobes.h>
+#include <linux/dyn-tick.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -193,6 +194,8 @@ 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-2.6.15-rc1-dt/arch/i386/kernel/smp.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/smp.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/smp.c
@@ -20,6 +20,7 @@
#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>
@@ -313,6 +314,8 @@ 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))
@@ -600,6 +603,8 @@ 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)
@@ -609,6 +614,9 @@ 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-2.6.15-rc1-dt/arch/i386/kernel/time.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/time.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/time.c
@@ -46,6 +46,7 @@
#include <linux/bcd.h>
#include <linux/efi.h>
#include <linux/mca.h>
+#include <linux/dyn-tick.h>

#include <asm/io.h>
#include <asm/smp.h>
@@ -245,7 +246,7 @@ EXPORT_SYMBOL(profile_pc);
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
*/
-static inline void do_timer_interrupt(int irq, struct pt_regs *regs)
+static inline void do_timer_interrupt(int irq, struct pt_regs *regs, int lost)
{
#ifdef CONFIG_X86_IO_APIC
if (timer_ack) {
@@ -263,7 +264,8 @@ static inline void do_timer_interrupt(in
}
#endif

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


if (MCA_bus) {
@@ -288,6 +290,8 @@ static inline void do_timer_interrupt(in
*/
irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
+ int lost;
+
/*
* Here we are in the timer irq handler. We just have irqs locally
* disabled but we don't know if the timer_bh is running on the other
@@ -297,9 +301,9 @@ irqreturn_t timer_interrupt(int irq, voi
*/
write_seqlock(&xtime_lock);

- cur_timer->mark_offset();
-
- do_timer_interrupt(irq, regs);
+ lost = cur_timer->mark_offset();
+
+ do_timer_interrupt(irq, regs, lost);

write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
@@ -425,7 +429,7 @@ static struct sysdev_class timer_sysclas


/* XXX this driverfs stuff should probably go elsewhere later -john */
-static struct sys_device device_timer = {
+struct sys_device device_timer = {
.id = 0,
.cls = &timer_sysclass,
};
@@ -481,5 +485,7 @@ void __init time_init(void)
cur_timer = select_timer();
printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);

+ dyn_tick_time_init(cur_timer);
+
time_init_hook();
}
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_pit.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/timers/timer_pit.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_pit.c
@@ -31,9 +31,10 @@ static int __init init_pit(char* overrid
return 0;
}

-static void mark_offset_pit(void)
+static int mark_offset_pit(void)
{
/* nothing needed */
+ return 1;
}

static unsigned long long monotonic_clock_pit(void)
@@ -147,6 +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(unsigned long jiffies_to_skip)
+{
+ int skip;
+ extern spinlock_t i8253_lock;
+ unsigned long flags;
+
+ skip = jiffies_to_skip * LATCH;
+ if (skip > 0xffff)
+ skip = 0xffff;
+
+ spin_lock_irqsave(&i8253_lock, flags);
+ outb_p(0x34, PIT_MODE); /* binary, mode 2, LSB/MSB, ch 0 */
+ outb_p(skip & 0xff, PIT_CH0); /* LSB */
+ outb(skip >> 8, PIT_CH0); /* MSB */
+ spin_unlock_irqrestore(&i8253_lock, flags);
+}

/* tsc timer_opts struct */
struct timer_opts timer_pit = {
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_pm.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/timers/timer_pm.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_pm.c
@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/device.h>
#include <linux/init.h>
+#include <linux/dyn-tick.h>
#include <asm/types.h>
#include <asm/timer.h>
#include <asm/smp.h>
@@ -28,7 +29,7 @@
#define PMTMR_TICKS_PER_SEC 3579545
#define PMTMR_EXPECTED_RATE \
((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10))
-
+#define PMTMR_TICKS_PER_JIFFY (PMTMR_EXPECTED_RATE / (CALIBRATE_LATCH/LATCH))

/* The I/O port the PMTMR resides at.
* The location is detected during setup_arch(),
@@ -127,7 +128,13 @@ pm_good:
if (verify_pmtmr_rate() != 0)
return -ENODEV;

+ printk("Using %u PM timer ticks per jiffy \n", PMTMR_TICKS_PER_JIFFY);
+
+ offset_tick = read_pmtmr();
+ setup_pit_timer();
+
init_cpu_khz();
+ set_dyn_tick_max_skip(((0xFFFFFF / 1000000) * 286 * HZ) >> 10);
return 0;
}

@@ -148,10 +155,9 @@ static inline u32 cyc2us(u32 cycles)
* this gets called during each timer interrupt
* - Called while holding the writer xtime_lock
*/
-static void mark_offset_pmtmr(void)
+static int mark_offset_pmtmr(void)
{
u32 lost, delta, last_offset;
- static int first_run = 1;
last_offset = offset_tick;

write_seqlock(&monotonic_lock);
@@ -161,29 +167,20 @@ static void mark_offset_pmtmr(void)
/* calculate tick interval */
delta = (offset_tick - last_offset) & ACPI_PM_MASK;

- /* convert to usecs */
- delta = cyc2us(delta);
-
/* update the monotonic base value */
- monotonic_base += delta * NSEC_PER_USEC;
+ monotonic_base += cyc2us(delta) * NSEC_PER_USEC;
write_sequnlock(&monotonic_lock);

/* convert to ticks */
delta += offset_delay;
- lost = delta / (USEC_PER_SEC / HZ);
- offset_delay = delta % (USEC_PER_SEC / HZ);
-
+ lost = delta / PMTMR_TICKS_PER_JIFFY;
+ offset_delay = delta % PMTMR_TICKS_PER_JIFFY;

/* compensate for lost ticks */
if (lost >= 2)
jiffies_64 += lost - 1;

- /* don't calculate delay for first run,
- or if we've got less then a tick */
- if (first_run || (lost < 1)) {
- first_run = 0;
- offset_delay = 0;
- }
+ return lost;
}

static int pmtmr_resume(void)
@@ -192,6 +189,7 @@ static int pmtmr_resume(void)
/* Assume this is the last mark offset time */
offset_tick = read_pmtmr();
write_sequnlock(&monotonic_lock);
+ offset_delay = 0;
return 0;
}

@@ -243,7 +241,7 @@ static unsigned long get_offset_pmtmr(vo
now = read_pmtmr();
delta = (now - offset)&ACPI_PM_MASK;

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


Index: linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_tsc.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/timers/timer_tsc.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_tsc.c
@@ -14,6 +14,7 @@
#include <linux/cpufreq.h>
#include <linux/string.h>
#include <linux/jiffies.h>
+#include <linux/dyn-tick.h>

#include <asm/timer.h>
#include <asm/io.h>
@@ -32,8 +33,6 @@ static unsigned long hpet_last;
static struct timer_opts timer_tsc;
#endif

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

static int use_tsc;
@@ -171,10 +170,19 @@ 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)
+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;

write_seqlock(&monotonic_lock);
@@ -202,9 +210,7 @@ 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 */
@@ -218,6 +224,8 @@ static void mark_offset_tsc_hpet(void)
delay_at_last_interrupt = hpet_current - offset;
ASM_MUL64_REG(temp, delay_at_last_interrupt,
hpet_usec_quotient, delay_at_last_interrupt);
+
+ return 1;
}
#endif

@@ -242,7 +250,7 @@ static void handle_cpufreq_delayed_get(v
* to verify the CPU frequency the timing core thinks the CPU is running
* at is still correct.
*/
-static inline void cpufreq_delayed_get(void)
+void cpufreq_delayed_get(void)
{
if (cpufreq_init && !cpufreq_delayed_issched) {
cpufreq_delayed_issched = 1;
@@ -321,7 +329,7 @@ static int __init cpufreq_tsc(void)
core_initcall(cpufreq_tsc);

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

int recalibrate_cpu_khz(void)
@@ -344,15 +352,15 @@ int recalibrate_cpu_khz(void)
}
EXPORT_SYMBOL(recalibrate_cpu_khz);

-static void mark_offset_tsc(void)
+static int mark_offset_tsc(void)
{
unsigned long lost,delay;
unsigned long delta = last_tsc_low;
int count;
int countmp;
static int count1 = 0;
- unsigned long long this_offset, last_offset;
- static int lost_count = 0;
+ unsigned long long last_offset;
+ int lost_count = 0;

write_seqlock(&monotonic_lock);
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
@@ -422,26 +430,11 @@ 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 */
@@ -452,8 +445,12 @@ static void mark_offset_tsc(void)
* between tsc and pit reads (as noted when
* usec delta is > 90% # of usecs/tick)
*/
- if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ))
+ if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ)) {
jiffies_64++;
+ lost++;
+ }
+
+ return 1;
}

static int __init init_tsc(char* override)
@@ -542,6 +539,8 @@ static int __init init_tsc(char* overrid
cpu_khz / 1000, cpu_khz % 1000);
}
set_cyc2ns_scale(cpu_khz);
+ set_dyn_tick_max_skip((0xFFFFFFFF /
+ (cpu_khz * 1000)) * HZ);
return 0;
}
}
Index: linux-2.6.15-rc1-dt/drivers/acpi/Kconfig
===================================================================
--- linux-2.6.15-rc1-dt.orig/drivers/acpi/Kconfig
+++ linux-2.6.15-rc1-dt/drivers/acpi/Kconfig
@@ -302,6 +302,8 @@ config X86_PM_TIMER
voltage scaling, unlike the commonly used Time Stamp Counter
(TSC) timing source.

+ This timer is selected by dyntick (NO_IDLE_HZ).
+
So, if you see messages like 'Losing too many ticks!' in the
kernel logs, and/or you are using this on a notebook which
does not yet have an HPET, you should say "Y" here.
Index: linux-2.6.15-rc1-dt/include/asm-i386/apic.h
===================================================================
--- linux-2.6.15-rc1-dt.orig/include/asm-i386/apic.h
+++ linux-2.6.15-rc1-dt/include/asm-i386/apic.h
@@ -121,6 +121,7 @@ extern void nmi_watchdog_tick (struct pt
extern int APIC_init_uniprocessor (void);
extern void disable_APIC_timer(void);
extern void enable_APIC_timer(void);
+extern void reprogram_apic_timer(unsigned long count);

extern void enable_NMI_through_LVT0 (void * dummy);

@@ -134,6 +135,7 @@ extern int disable_timer_pin_1;

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

#endif /* !CONFIG_X86_LOCAL_APIC */

Index: linux-2.6.15-rc1-dt/include/asm-i386/dyn-tick.h
===================================================================
--- /dev/null
+++ linux-2.6.15-rc1-dt/include/asm-i386/dyn-tick.h
@@ -0,0 +1,96 @@
+/*
+ * linux/include/asm-i386/dyn-tick.h
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ *
+ * 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);
+
+/*
+ * Needs to be different to the arch independant values specified in
+ * include/linux/dyn-tick.h to share the dyn_tick_timer.state struct
+ * member.
+ */
+#define DYN_TICK_APICABLE (1 << 3)
+
+#if (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC))
+static inline int cpu_has_local_apic(void)
+{
+ return (dyn_tick->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-2.6.15-rc1-dt/include/asm-i386/timer.h
===================================================================
--- linux-2.6.15-rc1-dt.orig/include/asm-i386/timer.h
+++ linux-2.6.15-rc1-dt/include/asm-i386/timer.h
@@ -19,7 +19,7 @@
*/
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 +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(unsigned long jiffies_to_skip);

/* Modifiers for buggy PIT handling */

Index: linux-2.6.15-rc1-dt/include/linux/dyn-tick.h
===================================================================
--- /dev/null
+++ linux-2.6.15-rc1-dt/include/linux/dyn-tick.h
@@ -0,0 +1,64 @@
+/*
+ * linux/include/linux/dyn-tick.h
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ *
+ * 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_SKIPPING (1 << 2)
+#define DYN_TICK_ENABLED (1 << 1)
+#define DYN_TICK_SUITABLE (1 << 0)
+
+#define DYN_TICK_MIN_SKIP 2
+
+struct dyn_tick_timer {
+ spinlock_t lock;
+
+ int (*arch_init) (void); /* dyn_tick init */
+ int (*arch_enable)(void); /* Enables dynamic tick */
+ int (*arch_disable)(void); /* Disables dynamic tick */
+ void (*arch_reprogram)(unsigned long); /* Reprograms the timer */
+ int (*arch_handler)(int, void *, struct pt_regs *);
+ void (*arch_all_cpus_idle) (int);
+
+ unsigned short state; /* Current state */
+ unsigned int min_skip; /* Max number of ticks to skip */
+ unsigned int max_skip; /* Max number of ticks to skip */
+};
+
+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
+extern int dyn_tick_enabled(void);
+extern void timer_dyn_reprogram(void);
+extern void set_dyn_tick_max_skip(unsigned int max_skip);
+
+#else /* CONFIG_NO_IDLE_HZ */
+static inline int dyn_tick_enabled(void)
+{
+ return 0;
+}
+
+static inline void set_dyn_tick_max_skip(unsigned int max_skip)
+{
+}
+#endif /* CONFIG_NO_IDLE_HZ */
+
+/* Pick up arch specific header */
+#include <asm/dyn-tick.h>
+
+#endif /* _DYN_TICK_TIMER_H */
Index: linux-2.6.15-rc1-dt/include/linux/timer.h
===================================================================
--- linux-2.6.15-rc1-dt.orig/include/linux/timer.h
+++ linux-2.6.15-rc1-dt/include/linux/timer.h
@@ -97,5 +97,6 @@ static inline void add_timer(struct time
extern void init_timers(void);
extern void run_local_timers(void);
extern void it_real_fn(unsigned long);
+extern void conditional_run_local_timers(void);

#endif
Index: linux-2.6.15-rc1-dt/kernel/dyn-tick.c
===================================================================
--- /dev/null
+++ linux-2.6.15-rc1-dt/kernel/dyn-tick.c
@@ -0,0 +1,190 @@
+/*
+ * linux/kernel/dyn-tick.c
+ *
+ * Beginnings of generic dynamic tick timer support
+ *
+ * Copyright (C) 2004 Nokia Corporation
+ * Written by Tony Lindgen <tony@xxxxxxxxxxx> and
+ * Tuukka Tikkanen <tuukka.tikkanen@xxxxxxxxxxxxxx>
+ *
+ * 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 "051118-1"
+
+int dyn_tick_enabled(void)
+{
+ return (dyn_tick->state & DYN_TICK_ENABLED);
+}
+
+static inline int dyn_tick_suitable(void)
+{
+ return (dyn_tick->state & DYN_TICK_SUITABLE);
+}
+
+/*
+ * Arch independent code needed to reprogram next timer interrupt.
+ * Gets called, with IRQs disabled, from cpu_idle() before entering idle loop.
+ */
+void timer_dyn_reprogram(void)
+{
+ int cpu = smp_processor_id();
+ unsigned int delta;
+
+ if (!dyn_tick_enabled())
+ return;
+
+ if (rcu_pending(cpu) || local_softirq_pending())
+ return;
+
+ /* 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->arch_reprogram(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->arch_all_cpus_idle(idle_time);
+
+ spin_unlock(dyn_tick_lock);
+ }
+
+ write_sequnlock(&xtime_lock);
+}
+
+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 = arch_timer;
+ printk(KERN_INFO "dyn-tick: Registering dynamic tick timer v%s\n",
+ DYN_TICK_VERSION);
+}
+
+/* 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)
+ dyn_tick->state |= DYN_TICK_ENABLED;
+ } else {
+ ret = dyn_tick->arch_disable();
+ if (ret == 0)
+ dyn_tick->state &= ~DYN_TICK_ENABLED;
+ }
+ 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 initialize dynamic tick after calibrate delay
+ */
+static int __init dyn_tick_late_init(void)
+{
+ int ret = 0;
+
+ 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: 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-2.6.15-rc1-dt/kernel/timer.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/kernel/timer.c
+++ linux-2.6.15-rc1-dt/kernel/timer.c
@@ -869,6 +869,13 @@ void run_local_timers(void)
raise_softirq(TIMER_SOFTIRQ);
}

+void conditional_run_local_timers(void)
+{
+ tvec_base_t *base = &__get_cpu_var(tvec_bases);
+
+ if (base->timer_jiffies != jiffies)
+ run_local_timers();
+}
/*
* Called by the timer interrupt. xtime_lock must already be taken
* by the timer IRQ!
Index: linux-2.6.15-rc1-dt/kernel/Makefile
===================================================================
--- linux-2.6.15-rc1-dt.orig/kernel/Makefile
+++ linux-2.6.15-rc1-dt/kernel/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_SECCOMP) += seccomp.o
obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
+obj-$(CONFIG_NO_IDLE_HZ) += dyn-tick.o

ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@xxxxxxxxxxxxxxxx>, the -fno-omit-frame-pointer is
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_cyclone.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/timers/timer_cyclone.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_cyclone.c
@@ -45,7 +45,7 @@ static seqlock_t monotonic_lock = SEQLOC
} while (high != cyclone_timer[1]);


-static void mark_offset_cyclone(void)
+static int mark_offset_cyclone(void)
{
unsigned long lost, delay;
unsigned long delta = last_cyclone_low;
@@ -101,6 +101,8 @@ static void mark_offset_cyclone(void)
*/
if (lost && abs(delay - delay_at_last_interrupt) > (900000/HZ))
jiffies_64++;
+
+ return 1;
}

static unsigned long get_offset_cyclone(void)
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_hpet.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/timers/timer_hpet.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_hpet.c
@@ -101,7 +101,7 @@ static unsigned long get_offset_hpet(voi
return edx;
}

-static void mark_offset_hpet(void)
+static int mark_offset_hpet(void)
{
unsigned long long this_offset, last_offset;
unsigned long offset;
@@ -124,6 +124,8 @@ static void mark_offset_hpet(void)
this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
monotonic_base += cycles_2_ns(this_offset - last_offset);
write_sequnlock(&monotonic_lock);
+
+ return 1;
}

static void delay_hpet(unsigned long loops)
Index: linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_none.c
===================================================================
--- linux-2.6.15-rc1-dt.orig/arch/i386/kernel/timers/timer_none.c
+++ linux-2.6.15-rc1-dt/arch/i386/kernel/timers/timer_none.c
@@ -1,9 +1,10 @@
#include <linux/init.h>
#include <asm/timer.h>

-static void mark_offset_none(void)
+static int mark_offset_none(void)
{
/* nothing needed */
+ return 1;
}

static unsigned long get_offset_none(void)

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