Messages in this thread Patch in this message | | | Date | Tue, 5 May 2009 12:16:05 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH v3] ftrace: add a tracepoint for __raise_softirq_irqoff() |
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* Xiao Guangrong (xiaoguangrong@cn.fujitsu.com) wrote: > From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> > > This patch is modified from Mathieu Desnoyers' patch. The original patch > can be found here: > http://marc.info/?l=linux-kernel&m=123791201816245&w=2 > This tracepoint can trace the time stamp when softirq action is raised. > > Changelog for v1 -> v2: > 1: Use TRACE_EVENT instead of DEFINE_TRACE > 2: Move the tracepoint from raise_softirq_irqoff() to > __raise_softirq_irqoff() > > Changelog for v2 -> v3: > Move the definition of __raise_softifq_irqoff() to .c file when > CONFIG_TRACEPOINTS is enabled, to avoid recursive includes > > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> > Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> > > --- > include/linux/interrupt.h | 6 ++++++ > include/trace/events/irq.h | 18 ++++++++++++++++++ > kernel/softirq.c | 8 ++++++++ > 3 files changed, 32 insertions(+), 0 deletions(-) > > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > index dd574d5..3143341 100644 > --- a/include/linux/interrupt.h > +++ b/include/linux/interrupt.h > @@ -361,7 +361,13 @@ asmlinkage void do_softirq(void); > asmlinkage void __do_softirq(void); > extern void open_softirq(int nr, void (*action)(struct softirq_action *)); > extern void softirq_init(void); > + > +#ifdef CONFIG_TRACEPOINTS > +extern void __raise_softirq_irqoff(unsigned int nr); > +#else > #define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
Can you put the trace_irq_softirq_raise(nr);
directly in the define rather than adding this weird CONFIG_TRACEPOINTS? (and change the define for a static inline), something like :
static inline void __raise_softirq_irqoff(unsigned int nr) { trace_irq_softirq_raise(nr); or_softirq_pending(1UL << (nr); }
This would ensure we don't add a function call on the __raise_softirq_irqoff() fast-path.
Beware of circular include dependencies though. The tracepoints are meant not to have this kind of problems (I try to keep the dependencies very minimalistic), but I wonder if Steven's TRACE_EVENT is now ok on this aspect.
If TRACE_EVENT happens to pose problems with circular header dependencies, then try moving to the DECLARE_TRACE/DEFINE_TRACE scheme which has been more thoroughly tested as a first step.
Mathieu
> +#endif > + > extern void raise_softirq_irqoff(unsigned int nr); > extern void raise_softirq(unsigned int nr); > extern void wakeup_softirqd(void); > diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h > index 32a9f7e..3c895bb 100644 > --- a/include/trace/events/irq.h > +++ b/include/trace/events/irq.h > @@ -128,6 +128,24 @@ TRACE_EVENT(softirq_exit, > TP_printk("softirq=%d action=%s", __entry->vec, __get_str(name)) > ); > > +TRACE_EVENT(irq_softirq_raise, > + > + TP_PROTO(unsigned int nr), > + > + TP_ARGS(nr), > + > + TP_STRUCT__entry( > + __field( unsigned int, nr ) > + ), > + > + TP_fast_assign( > + __entry->nr = nr; > + ), > + > + TP_printk("softirq=%d action=%s is raised", > + __entry->nr, softirq_to_name[__entry->nr]) > +); > + > #endif /* _TRACE_IRQ_H */ > > /* This part must be outside protection */ > diff --git a/kernel/softirq.c b/kernel/softirq.c > index b41fb71..bd0546b 100644 > --- a/kernel/softirq.c > +++ b/kernel/softirq.c > @@ -310,6 +310,14 @@ void irq_exit(void) > preempt_enable_no_resched(); > } > > +#ifdef CONFIG_TRACEPOINTS > +inline void __raise_softirq_irqoff(unsigned int nr) > +{ > + trace_irq_softirq_raise(nr); > + or_softirq_pending(1UL << (nr)); > +} > +#endif > + > /* > * This function must run with irqs disabled! > */ > -- > 1.6.1.2 >
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