Messages in this thread | | | Date | Thu, 5 Nov 2009 09:43:49 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH] softirq,tracing: enable to trace softirq raise latency |
| |
* Lai Jiangshan (laijs@cn.fujitsu.com) wrote: > > Add a tracepoint for tracing when softirq action is raised. > > It and the existed tracepoints complete softirq's tracepoints: > softirq_raise, softirq_entry and softirq_exit. > > And when this tracepoint is used in combination with > the softirq_entry tracepoint we can determine > the softirq raise latency. >
Hi Lai,
It generally looks good, we have a similar instrumentation point in the LTTng tree, and it's really useful. It's a good idea to instrument __raise_softirq_irqoff rather than just raise_softirq_irqoff: it includes the HI/TASKLET and HRTIMER softirqs.
There is just a small comment which should probably also be changed, please see below, besides that, you have my
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > index 75f3f00..b368d5d 100644 > --- a/include/linux/interrupt.h > +++ b/include/linux/interrupt.h > @@ -18,6 +18,7 @@ > #include <asm/atomic.h> > #include <asm/ptrace.h> > #include <asm/system.h> > +#include <trace/events/irq.h> > > /* > * These correspond to the IORESOURCE_IRQ_* defines in > @@ -372,7 +373,13 @@ 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); > -#define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0) > + > +static inline void __raise_softirq_irqoff(unsigned int nr) > +{ > + trace_softirq_raise(nr); > + or_softirq_pending(1UL << nr); > +} > + > 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 dcfcd44..799af09 100644 > --- a/include/trace/events/irq.h > +++ b/include/trace/events/irq.h > @@ -5,7 +5,9 @@ > #define _TRACE_IRQ_H > > #include <linux/tracepoint.h> > -#include <linux/interrupt.h> > + > +struct irqaction; > +struct softirq_action; > > #define softirq_name(sirq) { sirq##_SOFTIRQ, #sirq } > #define show_softirq_name(val) \ > @@ -83,6 +85,32 @@ TRACE_EVENT(irq_handler_exit, > ); > > /** > + * softirq_raise - called immediately when a softirq is raised > + * @nr: softirq vector number > + * > + * Tracepoint for tracing when softirq action is raised. > + * Also, when used in combination with the softirq_entry tracepoint > + * we can determine the softirq raise latency. > + */ > +TRACE_EVENT(softirq_raise, > + > + TP_PROTO(unsigned int nr), > + > + TP_ARGS(nr), > + > + TP_STRUCT__entry( > + __field( unsigned int, vec ) > + ), > + > + TP_fast_assign( > + __entry->vec = nr; > + ), > + > + TP_printk("vec=%d [action=%s]", __entry->vec, > + show_softirq_name(__entry->vec)) > +); > + > +/** > * softirq_entry - called immediately before the softirq handler > * @h: pointer to struct softirq_action > * @vec: pointer to first struct softirq_action in softirq_vec array
Please change this comment to "@vec: softirq vector number" while you are at it. The same probably needs to be done for softirq_exit. @vec are not pointers: these are offsets.
Thanks,
Mathieu
> @@ -100,11 +128,11 @@ TRACE_EVENT(softirq_entry, > TP_ARGS(h, vec), > > TP_STRUCT__entry( > - __field( int, vec ) > + __field( unsigned int, vec ) > ), > > TP_fast_assign( > - __entry->vec = (int)(h - vec); > + __entry->vec = (unsigned int)(h - vec); > ), > > TP_printk("vec=%d [action=%s]", __entry->vec, > @@ -129,11 +157,11 @@ TRACE_EVENT(softirq_exit, > TP_ARGS(h, vec), > > TP_STRUCT__entry( > - __field( int, vec ) > + __field( unsigned int, vec ) > ), > > TP_fast_assign( > - __entry->vec = (int)(h - vec); > + __entry->vec = (unsigned int)(h - vec); > ), > > TP_printk("vec=%d [action=%s]", __entry->vec, >
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
| |