Messages in this thread | | | Date | Wed, 03 Apr 2013 11:38:24 -0700 | From | Josh Stone <> | Subject | Re: systemtap broken by removal of register_timer_hook |
| |
On 04/03/2013 07:44 AM, Frank Ch. Eigler wrote: > Hi - > > On Wed, Apr 03, 2013 at 02:49:53PM +0200, Frederic Weisbecker wrote: > >> Sounds good, would you like to propose a version? We are also >> interested in a timer tick event tracepoint for dynticks debugging. > > How about this? > > Author: Frank Ch. Eigler <fche@redhat.com> > Date: Wed Apr 3 10:35:21 2013 -0400 > > profiling: add profile_tick tracepoint > > Commit ba6fdda4 removed the timer_hook mechanism for modules to listen > to profiling timer ticks (without having to set up more complicated > perf mechanisms). To reduce the impact on out-of-tree users, a > TRACE_EVENT-flavoured tracepoint is added in its place. Tested with > perf and systemtap.
One nice benefit over register_timer_hook() is that a tracepoint allows multiple consumers, like the old register_profile_notifier() did.
> > Cc: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Mel Gorman <mgorman@suse.de> > Signed-off-by: Frank Ch. Eigler <fche@redhat.com> > > diff --git a/include/trace/events/profile.h b/include/trace/events/profile.h > new file mode 100644 > index 0000000..b48b6fe > --- /dev/null > +++ b/include/trace/events/profile.h > @@ -0,0 +1,35 @@ > +#undef TRACE_SYSTEM > +#define TRACE_SYSTEM profile > + > +#if !defined(_TRACE_PROFILE_H) || defined(TRACE_HEADER_MULTI_READ) > +#define _TRACE_PROFILE_H > + > +#include <linux/tracepoint.h> > + > + > +struct pt_regs; > + > +/** > + * profile_tick - called when the profiling timer ticks > + * @regs: pointer to struct pt_regs* > + */ > + > +TRACE_EVENT(profile_tick, > + TP_PROTO(int type, struct pt_regs *regs), > + TP_ARGS(type, regs), > + TP_STRUCT__entry( > + __field( int, type ) > + __field( struct pt_regs*, regs ) > + ), > + TP_fast_assign( > + __entry->type = type; > + __entry->regs = regs; > + ), > + TP_printk("type=%d regs=%p", __entry->type, __entry->regs) > +);
I agree that full regs are good for the tracepoint in general, but I doubt that this pointer is useful for the printk. Maybe instead print instruction_pointer(__entry->regs)?
> + > + > +#endif /* _TRACE_PROFILE_H */ > + > +/* This part must be outside protection */ > +#include <trace/define_trace.h> > diff --git a/kernel/profile.c b/kernel/profile.c > index dc3384e..d61f921 100644 > --- a/kernel/profile.c > +++ b/kernel/profile.c > @@ -29,6 +29,9 @@ > #include <asm/irq_regs.h> > #include <asm/ptrace.h> > > +#define CREATE_TRACE_POINTS > +#include <trace/events/profile.h> > + > struct profile_hit { > u32 pc, hits; > }; > @@ -414,6 +417,8 @@ void profile_tick(int type) > { > struct pt_regs *regs = get_irq_regs(); > > + trace_profile_tick(type, regs); > + > if (!user_mode(regs) && prof_cpu_mask != NULL && > cpumask_test_cpu(smp_processor_id(), prof_cpu_mask)) > profile_hit(type, (void *)profile_pc(regs)); >
| |