ia64: VIRT_CPU_ACCOUNTING (accurate cpu time accounting)

Next, we need to stop sampling in timer interrupt which used for tick-based cpu time accounting.

Now the stime/utime of threads are updated in a function update_process_times(), that is called from timer_interrupt().

[arch/ia64/kernel/time.c]
46 static irqreturn_t
47 timer_interrupt (int irq, void *dev_id)
48 {
　:
65 while (1) {
66 update_process_times(user_mode(get_irq_regs()));
　:
70 if (smp_processor_id() = time_keeper_id) {
　:
78 do_timer(1);
　:
84 if (time_after(new_itm, ia64_get_itc()))
85 break;
　:
92 }

This update_process_times() is defined in kernel/timer.c. Therefore, I copied this function into ia64 region to ready to modify it as we like.

This patch just do copy. Later change will be done.

Thanks,
H.Seto

---
 arch/ia64/kernel/time.c |   30 +++++++++++++++++++++++++++++-
 1 files changed, 29 insertions(+), 1 deletion(-)

Index: linux-2.6.23/arch/ia64/kernel/time.c =================================--- linux-2.6.23.orig/arch/ia64/kernel/time.c +++ linux-2.6.23/arch/ia64/kernel/time.c
@@ -61,6 +61,9 @@

#ifdef CONFIG_VIRT_CPU_ACCOUNTING

+#include <linux/kernel_stat.h>
+#include <linux/posix-timers.h>
+
/*
* Account time for a transition between system, hard irq
* or soft irq state.
@@ -70,6 +73,31 @@

}

+/*
+ * Called from the timer interrupt handler to charge one tick to the current
+ * process. user_tick is 1 if the tick is user time, 0 for system.
+ */
+static inline void ia64_update_process_times(int user_tick)
+{
+ struct task_struct *p = current;
+ int cpu = smp_processor_id();
+
+ /* Note: this timer irq context must be accounted for as well. */
+ if (user_tick)
+ account_user_time(p, jiffies_to_cputime(1));
+ else
+ account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
+ run_local_timers();
+ if (rcu_pending(cpu))
+ rcu_check_callbacks(cpu, user_tick);
+ scheduler_tick();
+ run_posix_cpu_timers(p);
+}
+
+#else /* CONFIG_VIRT_CPU_ACCOUNTING */
+
+#define ia64_update_process_times(utick) update_process_times(utick) +
#endif /* CONFIG_VIRT_CPU_ACCOUNTING */

static irqreturn_t
@@ -92,7 +120,7 @@
profile_tick(CPU_PROFILING);

while (1) {
- update_process_times(user_mode(get_irq_regs()));
+ ia64_update_process_times(user_mode(get_irq_regs()));

new_itm += local_cpu_data->itm_delta;