Commit-ID: 6795b85c6a4f690e61e7be31aa150d945c723fb5
Gitweb: http://git.kernel.org/tip/6795b85c6a4f690e61e7be31aa150d945c723fb5
Author: Anton Blanchard <anton@xxxxxxxxx>
AuthorDate: Mon, 26 Oct 2009 18:49:14 +0000
Committer: Paul Mackerras <paulus@xxxxxxxxx>
CommitDate: Wed, 28 Oct 2009 16:13:03 +1100
powerpc: tracing: Add powerpc tracepoints for timer entry and exit
We can monitor the effectiveness of our power management of both the
kernel and hypervisor by probing the timer interrupt. For example, on
this box we see 10.37s timer interrupts on an idle core:
<idle>-0 [010] 3900.671297: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
<idle>-0 [010] 3900.671302: timer_interrupt_exit: pt_regs=c0000000ce1e7b10
<idle>-0 [010] 3911.042963: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
<idle>-0 [010] 3911.042968: timer_interrupt_exit: pt_regs=c0000000ce1e7b10
<idle>-0 [010] 3921.414630: timer_interrupt_entry: pt_regs=c0000000ce1e7b10
<idle>-0 [010] 3921.414635: timer_interrupt_exit: pt_regs=c0000000ce1e7b10
Since we have a 207MHz decrementer it will go negative and fire every 10.37s
even if Linux is completely idle.
Signed-off-by: Anton Blanchard <anton@xxxxxxxxx>
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
---
arch/powerpc/include/asm/trace.h | 34 ++++++++++++++++++++++++++++++++++
arch/powerpc/kernel/time.c | 6 ++++++
2 files changed, 40 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h
index 187696d..b558c31 100644
--- a/arch/powerpc/include/asm/trace.h
+++ b/arch/powerpc/include/asm/trace.h
@@ -42,6 +42,40 @@ TRACE_EVENT(irq_exit,
TP_printk("pt_regs=%p", __entry->regs)
);
+TRACE_EVENT(timer_interrupt_entry,
+
+ TP_PROTO(struct pt_regs *regs),
+
+ TP_ARGS(regs),
+
+ TP_STRUCT__entry(
+ __field(struct pt_regs *, regs)
+ ),
+
+ TP_fast_assign(
+ __entry->regs = regs;
+ ),
+
+ TP_printk("pt_regs=%p", __entry->regs)
+);
+
+TRACE_EVENT(timer_interrupt_exit,
+
+ TP_PROTO(struct pt_regs *regs),
+
+ TP_ARGS(regs),
+
+ TP_STRUCT__entry(
+ __field(struct pt_regs *, regs)
+ ),
+
+ TP_fast_assign(
+ __entry->regs = regs;
+ ),
+
+ TP_printk("pt_regs=%p", __entry->regs)
+);
+
#endif /* _TRACE_POWERPC_H */
#undef TRACE_INCLUDE_PATH
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 92dc844..d6e88df 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -54,6 +54,7 @@
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/perf_event.h>
+#include <asm/trace.h>
#include <asm/io.h>
#include <asm/processor.h>
@@ -571,6 +572,8 @@ void timer_interrupt(struct pt_regs * regs)
struct clock_event_device *evt = &decrementer->event;
u64 now;
+ trace_timer_interrupt_entry(regs);
+
/* Ensure a positive value is written to the decrementer, or else
* some CPUs will continuue to take decrementer exceptions */
set_dec(DECREMENTER_MAX);
@@ -590,6 +593,7 @@ void timer_interrupt(struct pt_regs * regs)
now = decrementer->next_tb - now;
if (now <= DECREMENTER_MAX)
set_dec((int)now);
+ trace_timer_interrupt_exit(regs);
return;
}
old_regs = set_irq_regs(regs);
@@ -620,6 +624,8 @@ void timer_interrupt(struct pt_regs * regs)
irq_exit();
set_irq_regs(old_regs);
+
+ trace_timer_interrupt_exit(regs);
}
void wakeup_decrementer(void)
--
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