From: Anton Blanchard <anton@samba.org>
To: Steven Rostedt <rostedt@goodmis.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
benh@kernel.crashing.org
Cc: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 2/6] powerpc: tracing: Add powerpc tracepoints for timer entry and exit
Date: Tue, 27 Oct 2009 15:49:14 +1100 [thread overview]
Message-ID: <20091027044914.GC3085@kryten> (raw)
In-Reply-To: <20091027044742.GB3085@kryten>
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@samba.org>
---
Index: linux.trees.git/arch/powerpc/kernel/time.c
===================================================================
--- linux.trees.git.orig/arch/powerpc/kernel/time.c 2009-10-07 17:21:21.000000000 +1100
+++ linux.trees.git/arch/powerpc/kernel/time.c 2009-10-07 17:21:52.000000000 +1100
@@ -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 * re
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 * re
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 * re
irq_exit();
set_irq_regs(old_regs);
+
+ trace_timer_interrupt_exit(regs);
}
void wakeup_decrementer(void)
Index: linux.trees.git/arch/powerpc/include/asm/trace.h
===================================================================
--- linux.trees.git.orig/arch/powerpc/include/asm/trace.h 2009-10-07 17:22:25.000000000 +1100
+++ linux.trees.git/arch/powerpc/include/asm/trace.h 2009-10-07 17:23:20.000000000 +1100
@@ -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
next prev parent reply other threads:[~2009-10-27 4:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-27 4:47 [PATCH 1/6] powerpc: tracing: Add powerpc tracepoints for interrupt entry and exit Anton Blanchard
2009-10-27 4:49 ` Anton Blanchard [this message]
2009-10-27 4:50 ` [PATCH 3/6] powerpc: tracing: Add hypervisor call tracepoints Anton Blanchard
2009-10-27 4:51 ` [PATCH 4/6] powerpc: tracing: Give hypervisor call tracepoints access to arguments Anton Blanchard
2009-10-27 4:51 ` [PATCH 5/6] powerpc: Disable HCALL_STATS by default Anton Blanchard
2009-10-27 4:52 ` [PATCH 6/6] powerpc: Export powerpc_debugfs_root Anton Blanchard
2009-10-27 5:02 ` hypervisor call trace module Anton Blanchard
2009-10-27 22:00 ` [PATCH 1/6] powerpc: tracing: Add powerpc tracepoints for interrupt entry and exit Steven Rostedt
2009-10-27 23:41 ` Benjamin Herrenschmidt
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