[PATCH] remove i386 dynamic ticks ifdefs

From: Con Kolivas
Date: Thu Jul 28 2005 - 21:09:41 EST

Hi Tony

I assume you're maintaining the dyn tick patches for i386 posted on the muru
website as your email is listed there. I thought you might be interested in
this patch for dyn-ticks which removes most of the #ifdefs out of common code
paths as per linux kernel style and moves more code into dyn-tick.c. Most of
it is straight forward code reorganisation, but to keep do_timer_interrupt
inlined I'd have to move it's code around somewhat. That may be a better
option but I've tried to fiddle with the mainline code as little as possible.

Patch applies to 2.6.12 with patch-dynamic-tick-2.6.12-rc6-050610-1 applied

cc'ed lkml just for public record of the patch.

Cheers,
Con
Move most of the dynamic ticks code that is #ifdef'd out of code paths and
put it into dyn-tick.c

Signed-off-by: Con Kolivas <kernel@xxxxxxxxxxx>

arch/i386/kernel/Makefile | 2
arch/i386/kernel/apic.c | 36 ----------
arch/i386/kernel/dyn-tick.c | 146 ++++++++++++++++++++++++++++++++++++++++++++
arch/i386/kernel/irq.c | 5 -
arch/i386/kernel/time.c | 72 ---------------------
include/asm/dyn-tick.h | 4 -
include/linux/dyn-tick.h | 12 +++
7 files changed, 165 insertions(+), 112 deletions(-)

Index: linux-2.6.12-dt/arch/i386/kernel/apic.c
===================================================================
--- linux-2.6.12-dt.orig/arch/i386/kernel/apic.c 2005-07-29 01:43:15.000000000 +1000
+++ linux-2.6.12-dt/arch/i386/kernel/apic.c 2005-07-29 01:49:05.000000000 +1000
@@ -932,11 +932,8 @@ static void __setup_APIC_LVTT(unsigned i

apic_timer_val = clocks/APIC_DIVISOR;

-#ifdef CONFIG_NO_IDLE_HZ
- /* Local APIC timer is 24-bit */
if (apic_timer_val)
- dyn_tick->max_skip = 0xffffff / apic_timer_val;
-#endif
+ set_dyn_tick_max_skip(apic_timer_val);

apic_write_around(APIC_TMICT, apic_timer_val);
}
@@ -1051,12 +1048,7 @@ void __init setup_boot_APIC_clock(void)
*/
setup_APIC_timer(calibration_result);

-#ifdef CONFIG_NO_IDLE_HZ
- if (calibration_result)
- dyn_tick->state |= DYN_TICK_USE_APIC;
- else
- printk(KERN_INFO "dyn-tick: Cannot use local APIC\n");
-#endif
+ setup_dyn_tick_use_apic(calibration_result);

local_irq_enable();
}
@@ -1086,18 +1078,6 @@ void enable_APIC_timer(void)
}
}

-#if defined(CONFIG_NO_IDLE_HZ)
-void reprogram_apic_timer(unsigned int count)
-{
- unsigned long flags;
-
- count *= apic_timer_val;
- local_irq_save(flags);
- apic_write_around(APIC_TMICT, count);
- local_irq_restore(flags);
-}
-#endif
-
/*
* the frequency of the profiling timer can be changed
* by writing a multiplier value into /proc/profile.
@@ -1210,21 +1190,11 @@ fastcall void smp_apic_timer_interrupt(s
*/
irq_enter();

-#ifdef CONFIG_NO_IDLE_HZ
/*
* Check if we need to wake up PIT interrupt handler.
* Otherwise just wake up local APIC timer.
*/
- do {
- seq = read_seqbegin(&xtime_lock);
- if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING)) {
- if (dyn_tick->skip_cpu == cpu && dyn_tick->skip > DYN_TICK_MIN_SKIP)
- dyn_tick->interrupt(99, NULL, regs);
- else
- reprogram_apic_timer(1);
- }
- } while (read_seqretry(&xtime_lock, seq));
-#endif
+ wakeup_pit_or_apic(seq, cpu, &regs);

smp_local_timer_interrupt(regs);
irq_exit();
Index: linux-2.6.12-dt/arch/i386/kernel/dyn-tick.c
===================================================================
--- linux-2.6.12-dt.orig/arch/i386/kernel/dyn-tick.c 2005-07-29 01:43:15.000000000 +1000
+++ linux-2.6.12-dt/arch/i386/kernel/dyn-tick.c 2005-07-29 11:46:48.000000000 +1000
@@ -17,6 +17,7 @@
#include <linux/module.h>
#include <linux/dyn-tick.h>

+#ifdef CONFIG_NO_IDLE_HZ
void arch_reprogram_timer(void)
{
if (cpu_has_local_apic()) {
@@ -43,3 +44,148 @@ int __init dyn_tick_init(void)
return 0;
}
arch_initcall(dyn_tick_init);
+
+static unsigned long long last_tick;
+
+/*
+ * This interrupt handler updates the time based on number of jiffies skipped
+ * It would be somewhat more optimized to have a customa handler in each timer
+ * using hardware ticks instead of nanoseconds. Note that CONFIG_NO_IDLE_HZ
+ * currently disables timer fallback on skipped jiffies.
+ */
+irqreturn_t dyn_tick_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ unsigned long flags;
+ volatile unsigned long long now;
+ unsigned int skipped = 0;
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+ now = cur_timer->monotonic_clock();
+ while (now - last_tick >= NS_TICK_LEN) {
+ last_tick += NS_TICK_LEN;
+ cur_timer->mark_offset();
+ do_timer_interrupt(irq, NULL, regs);
+ skipped++;
+ }
+ if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING)) {
+ dyn_tick->skip = 1;
+ if (cpu_has_local_apic())
+ reprogram_apic_timer(dyn_tick->skip);
+ reprogram_pit_timer(dyn_tick->skip);
+ dyn_tick->state |= DYN_TICK_ENABLED;
+ dyn_tick->state &= ~DYN_TICK_SKIPPING;
+ }
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ return IRQ_HANDLED;
+}
+
+int __init dyn_tick_arch_init(void)
+{
+ unsigned long flags;
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+ last_tick = cur_timer->monotonic_clock();
+ dyn_tick->skip = 1;
+ if (!(dyn_tick->state & DYN_TICK_USE_APIC) || !cpu_has_local_apic())
+ dyn_tick->max_skip = 0xffff/LATCH; /* PIT timer length */
+ printk(KERN_INFO "dyn-tick: Maximum ticks to skip limited to %i\n",
+ dyn_tick->max_skip);
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ dyn_tick->interrupt = dyn_tick_timer_interrupt;
+ replace_timer_interrupt(dyn_tick->interrupt);
+
+ return 0;
+}
+
+/* Reproduced functions below here */
+inline void set_dyn_tick_max_skip(u32 apic_timer_val)
+{
+ dyn_tick->max_skip = 0xffffff / apic_timer_val;
+}
+
+inline void setup_dyn_tick_use_apic(unsigned int calibration_result)
+{
+ if (calibration_result)
+ dyn_tick->state |= DYN_TICK_USE_APIC;
+ else
+ printk(KERN_INFO "dyn-tick: Cannot use local APIC\n");
+}
+
+void wakeup_pit_or_apic(unsigned long seq, int cpu, struct pt_regs *regs)
+{
+ do {
+ seq = read_seqbegin(&xtime_lock);
+ if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING)) {
+ if (dyn_tick->skip_cpu == cpu && dyn_tick->skip > DYN_TICK_MIN_SKIP)
+ dyn_tick->interrupt(99, NULL, regs);
+ else
+ reprogram_apic_timer(1);
+ }
+ } while (read_seqretry(&xtime_lock, seq));
+}
+
+void dyn_tick_interrupt(int irq, struct pt_regs *regs)
+{
+ if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING) && irq != 0)
+ dyn_tick->interrupt(irq, NULL, regs);
+}
+
+void dyn_tick_time_init(struct timer_opts *cur_timer)
+{
+ if (strncmp(cur_timer->name, "tsc", 3) == 0 ||
+ strncmp(cur_timer->name, "pmtmr", 3) == 0) {
+ dyn_tick->state |= DYN_TICK_SUITABLE;
+ printk(KERN_INFO "dyn-tick: Found suitable timer: %s\n",
+ cur_timer->name);
+ } else
+ printk(KERN_ERR "dyn-tick: Cannot use timer %s\n",
+ cur_timer->name);
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+void reprogram_apic_timer(unsigned int count)
+{
+ unsigned long flags;
+
+ count *= apic_timer_val;
+ local_irq_save(flags);
+ apic_write_around(APIC_TMICT, count);
+ local_irq_restore(flags);
+}
+#else
+void reprogram_apic_timer(unsigned int count)
+{
+}
+
+#endif
+
+#else
+inline void set_dyn_tick_max_skip(u32 apic_timer_val)
+{
+}
+
+void reprogram_apic_timer(unsigned int count)
+{
+}
+
+inline void setup_dyn_tick_use_apic(unsigned int calibration_result)
+{
+}
+
+void wakeup_pit_or_apic(unsigned long seq, int cpu, struct pt_regs *regs)
+{
+}
+
+void dyn_tick_interrupt(int irq, struct pt_regs *regs)
+{
+}
+
+void dyn_tick_time_init(struct timer_opts *cur_timer)
+{
+}
+
+#endif
+
+
Index: linux-2.6.12-dt/arch/i386/kernel/irq.c
===================================================================
--- linux-2.6.12-dt.orig/arch/i386/kernel/irq.c 2005-07-29 01:43:15.000000000 +1000
+++ linux-2.6.12-dt/arch/i386/kernel/irq.c 2005-07-29 02:03:33.000000000 +1000
@@ -74,10 +74,7 @@ fastcall unsigned int do_IRQ(struct pt_r
}
#endif

-#ifdef CONFIG_NO_IDLE_HZ
- if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING) && irq != 0)
- dyn_tick->interrupt(irq, NULL, regs);
-#endif
+ dyn_tick_interrupt(irq, regs);

#ifdef CONFIG_4KSTACKS

Index: linux-2.6.12-dt/arch/i386/kernel/Makefile
===================================================================
--- linux-2.6.12-dt.orig/arch/i386/kernel/Makefile 2005-07-29 00:06:26.000000000 +1000
+++ linux-2.6.12-dt/arch/i386/kernel/Makefile 2005-07-29 02:05:54.000000000 +1000
@@ -31,7 +31,7 @@ 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-y += dyn-tick.o
obj-$(CONFIG_EFI) += efi.o efi_stub.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o

Index: linux-2.6.12-dt/arch/i386/kernel/time.c
===================================================================
--- linux-2.6.12-dt.orig/arch/i386/kernel/time.c 2005-07-29 01:43:15.000000000 +1000
+++ linux-2.6.12-dt/arch/i386/kernel/time.c 2005-07-29 11:53:52.000000000 +1000
@@ -248,7 +248,7 @@ EXPORT_SYMBOL(profile_pc);
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
*/
-static inline void do_timer_interrupt(int irq, void *dev_id,
+void do_timer_interrupt(int irq, void *dev_id,
struct pt_regs *regs)
{
#ifdef CONFIG_X86_IO_APIC
@@ -309,43 +309,6 @@ irqreturn_t timer_interrupt(int irq, voi
return IRQ_HANDLED;
}

-#ifdef CONFIG_NO_IDLE_HZ
-static unsigned long long last_tick;
-
-/*
- * This interrupt handler updates the time based on number of jiffies skipped
- * It would be somewhat more optimized to have a customa handler in each timer
- * using hardware ticks instead of nanoseconds. Note that CONFIG_NO_IDLE_HZ
- * currently disables timer fallback on skipped jiffies.
- */
-irqreturn_t dyn_tick_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
-{
- unsigned long flags;
- volatile unsigned long long now;
- unsigned int skipped = 0;
-
- write_seqlock_irqsave(&xtime_lock, flags);
- now = cur_timer->monotonic_clock();
- while (now - last_tick >= NS_TICK_LEN) {
- last_tick += NS_TICK_LEN;
- cur_timer->mark_offset();
- do_timer_interrupt(irq, NULL, regs);
- skipped++;
- }
- if (dyn_tick->state & (DYN_TICK_ENABLED | DYN_TICK_SKIPPING)) {
- dyn_tick->skip = 1;
- if (cpu_has_local_apic())
- reprogram_apic_timer(dyn_tick->skip);
- reprogram_pit_timer(dyn_tick->skip);
- dyn_tick->state |= DYN_TICK_ENABLED;
- dyn_tick->state &= ~DYN_TICK_SKIPPING;
- }
- write_sequnlock_irqrestore(&xtime_lock, flags);
-
- return IRQ_HANDLED;
-}
-#endif /* CONFIG_NO_IDLE_HZ */
-
/* not static: needed by APM */
unsigned long get_cmos_time(void)
{
@@ -490,28 +453,6 @@ static void __init hpet_time_init(void)
}
#endif

-#ifdef CONFIG_NO_IDLE_HZ
-
-int __init dyn_tick_arch_init(void)
-{
- unsigned long flags;
-
- write_seqlock_irqsave(&xtime_lock, flags);
- last_tick = cur_timer->monotonic_clock();
- dyn_tick->skip = 1;
- if (!(dyn_tick->state & DYN_TICK_USE_APIC) || !cpu_has_local_apic())
- dyn_tick->max_skip = 0xffff/LATCH; /* PIT timer length */
- printk(KERN_INFO "dyn-tick: Maximum ticks to skip limited to %i\n",
- dyn_tick->max_skip);
- write_sequnlock_irqrestore(&xtime_lock, flags);
-
- dyn_tick->interrupt = dyn_tick_timer_interrupt;
- replace_timer_interrupt(dyn_tick->interrupt);
-
- return 0;
-}
-#endif /* CONFIG_NO_IDLE_HZ */
-
void __init time_init(void)
{
#ifdef CONFIG_HPET_TIMER
@@ -532,16 +473,7 @@ void __init time_init(void)
cur_timer = select_timer();
printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);

-#ifdef CONFIG_NO_IDLE_HZ
- if (strncmp(cur_timer->name, "tsc", 3) == 0 ||
- strncmp(cur_timer->name, "pmtmr", 3) == 0) {
- dyn_tick->state |= DYN_TICK_SUITABLE;
- printk(KERN_INFO "dyn-tick: Found suitable timer: %s\n",
- cur_timer->name);
- } else
- printk(KERN_ERR "dyn-tick: Cannot use timer %s\n",
- cur_timer->name);
-#endif
+ dyn_tick_time_init(cur_timer);

time_init_hook();
}
Index: linux-2.6.12-dt/include/asm/dyn-tick.h
===================================================================
--- linux-2.6.12-dt.orig/include/asm/dyn-tick.h 2005-07-29 01:43:15.000000000 +1000
+++ linux-2.6.12-dt/include/asm/dyn-tick.h 2005-07-29 01:58:54.000000000 +1000
@@ -19,11 +19,7 @@ extern void reprogram_pit_timer(int jiff
extern void reprogram_apic_timer(unsigned int count);
extern void replace_timer_interrupt(void * new_handler);

-#if defined(CONFIG_NO_IDLE_HZ) && defined(CONFIG_X86_LOCAL_APIC)
extern void reprogram_apic_timer(unsigned int count);
-#else
-#define reprogram_apic_timer(x) do {} while (0)
-#endif

#if defined(CONFIG_DYN_TICK_USE_APIC) && (defined(CONFIG_SMP) || defined(CONFIG_X86_UP_APIC))
#define cpu_has_local_apic() (dyn_tick->state & DYN_TICK_USE_APIC)
Index: linux-2.6.12-dt/include/linux/dyn-tick.h
===================================================================
--- linux-2.6.12-dt.orig/include/linux/dyn-tick.h 2005-07-29 01:43:15.000000000 +1000
+++ linux-2.6.12-dt/include/linux/dyn-tick.h 2005-07-29 11:41:48.000000000 +1000
@@ -14,6 +14,7 @@
#define _DYN_TICK_TIMER_H

#include <linux/interrupt.h>
+#include <asm/timer.h>

#define DYN_TICK_TIMER_INT (1 << 4)
#define DYN_TICK_USE_APIC (1 << 3)
@@ -39,6 +40,14 @@ struct dyn_tick_timer {

extern struct dyn_tick_state * dyn_tick;
extern void dyn_tick_register(struct dyn_tick_timer * new_timer);
+extern inline void set_dyn_tick_max_skip(u32 apic_timer_val);
+extern void reprogram_apic_timer(unsigned int count);
+extern inline void setup_dyn_tick_use_apic(unsigned int calibration_result);
+extern void wakeup_pit_or_apic(unsigned long seq, int cpu, struct pt_regs *regs);
+extern void dyn_tick_interrupt(int irq, struct pt_regs *regs);
+extern void dyn_tick_time_init(struct timer_opts *cur_timer);
+extern void do_timer_interrupt(int irq, void *dev_id,
+ struct pt_regs *regs);

#define NS_TICK_LEN ((1 * 1000000000)/HZ)
#define DYN_TICK_MIN_SKIP 2
@@ -47,6 +56,9 @@ extern void dyn_tick_register(struct dyn
#ifdef CONFIG_NO_IDLE_HZ

extern unsigned long dyn_tick_reprogram_timer(void);
+extern irqreturn_t dyn_tick_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
+extern int __init dyn_tick_arch_init(void);
+
#define dyn_tick_enabled() (dyn_tick->state & DYN_TICK_ENABLED)

#else

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