From 6795b85c6a4f690e61e7be31aa150d945c723fb5 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Mon, 26 Oct 2009 18:49:14 +0000 Subject: [PATCH] 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: -0 [010] 3900.671297: timer_interrupt_entry: pt_regs=c0000000ce1e7b10 -0 [010] 3900.671302: timer_interrupt_exit: pt_regs=c0000000ce1e7b10 -0 [010] 3911.042963: timer_interrupt_entry: pt_regs=c0000000ce1e7b10 -0 [010] 3911.042968: timer_interrupt_exit: pt_regs=c0000000ce1e7b10 -0 [010] 3921.414630: timer_interrupt_entry: pt_regs=c0000000ce1e7b10 -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 Signed-off-by: Paul Mackerras --- arch/powerpc/include/asm/trace.h | 34 ++++++++++++++++++++++++++++++++ arch/powerpc/kernel/time.c | 6 ++++++ 2 files changed, 40 insertions(+) diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h index 187696da5ae7..b558c31d409e 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 92dc844299b6..d6e88df4630c 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -54,6 +54,7 @@ #include #include #include +#include #include #include @@ -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) -- GitLab