> * Gautham R Shenoy (
ego@in.ibm.com) wrote:
> > On Thu, Jan 03, 2008 at 11:30:55AM -0500, Mathieu Desnoyers wrote:
> > > * K. Prasad (
prasad@linux.vnet.ibm.com) wrote:
> > > > This patch converts the tracing mechanism of Preempt RCU boosting into
> > > > markers. The handler functions for these markers are included inside
> > > > rcupreempt_trace.c and will be included only when PREEMPT_RCU_BOOST is
> > > > chosen.
> > > >
> > > > Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
> > > > ---
> > > > include/linux/rcupreempt_trace.h | 46 ++++++++
> > > > kernel/rcupreempt-boost.c | 211 ++++-----------------------------------
> > > > kernel/rcupreempt_trace.c | 183 +++++++++++++++++++++++++++++++++
> > > > 3 files changed, 251 insertions(+), 189 deletions(-)
> > > >
> > > > Index: linux-2.6.24-rc2-rt1.MARKER_PATCHES_NEW/include/linux/rcupreempt_trace.h
> > > > ===================================================================
> > > > --- linux-2.6.24-rc2-rt1.MARKER_PATCHES_NEW.orig/include/linux/rcupreempt_trace.h
> > > > +++ linux-2.6.24-rc2-rt1.MARKER_PATCHES_NEW/include/linux/rcupreempt_trace.h
> > > > @@ -102,5 +102,51 @@ extern int rcupreempt_flip_flag(int cpu)
> > > > extern int rcupreempt_mb_flag(int cpu);
> > > > extern char *rcupreempt_try_flip_state_name(void);
> > > >
> > > > +#ifdef CONFIG_PREEMPT_RCU_BOOST
> > > > +struct preempt_rcu_boost_trace {
> > > > + unsigned long rbs_stat_task_boost_called;
> > > > + unsigned long rbs_stat_task_boosted;
> > > > + unsigned long rbs_stat_boost_called;
> > > > + unsigned long rbs_stat_try_boost;
> > > > + unsigned long rbs_stat_boosted;
> > > > + unsigned long rbs_stat_unboost_called;
> > > > + unsigned long rbs_stat_unboosted;
> > > > + unsigned long rbs_stat_try_boost_readers;
> > > > + unsigned long rbs_stat_boost_readers;
> > > > + unsigned long rbs_stat_try_unboost_readers;
> > > > + unsigned long rbs_stat_unboost_readers;
> > > > + unsigned long rbs_stat_over_taken;
> > > > +};
> > > > +
> > > > +#define DEFINE_PREEMPT_RCU_BOOST_MARKER_HANDLER(preempt_rcu_boost_var) \
> > > > +void preempt_rcu_boost_var##_callback(const struct marker *mdata, \
> > > > + void *private_data, const char *format, ...) \
> > > > +{ \
> > > > + va_list ap; \
> > > > + int cpu; \
> > > > + struct preempt_rcu_boost_trace *boost_trace; \
> > > > + va_start(ap, format); \
> > > > + cpu = va_arg(ap, typeof(unsigned int)); \
> > >
> > > (sorry for late response, I just came back from vacation)
> > >
> > > Instead of passing the cpu id as a marker parameter, why don't you
> > > simply use smp_processor_id() right here ?
> > >
> >
> > Agreed.
> >
> > Also in patch 1, in cases where we're using markers in place of RCU_TRACE_ME(),
> > we need not pass the parameter and simply use smp_processor_id().
> >
> > It's only the RCU_TRACE_RDP() that requires cpuid to be passed.
> >
>
>
> And it would help if you declare the format string with something like :
>
> "cpuid %u" instead of "%u"
>
> This way, if a generic tracer like LTTng dumps the traces and later a
> plugin in an analysis tool like LTTV have to hook on a specific field of
> your event, it can access it by specifying the marker name and field
> name. And even if fields are added to this event, it won't break
> compatibility as long as this field is there and have the same name.
>
> Mathieu
