Re: [PATCH -v2] tracing: lockdep tracepoints

[Peter Zijlstra <peterz@infradead.org>]

On Wed, 2009-03-04 at 12:43 +0100, Ingo Molnar wrote:
> 
> > +TRACE_FORMAT(lock_contended,
> > +     TPPROTO(struct lockdep_map *lock, unsigned long ip),
> > +     TPARGS(lock, ip),
> > +     TPFMT("%s", lock->name)
> > +     );
> 
> Would it be possible to use the C syntax tracepoints perhaps? 
> They are bigger:
> 
>      TRACE_EVENT_FORMAT(sched_switch,
>         TPPROTO(struct rq *rq, struct task_struct *prev,
>                 struct task_struct *next),
>         TPARGS(rq, prev, next),
>         TPFMT("task %s:%d ==> %s:%d",
>               prev->comm, prev->pid, next->comm, next->pid),
>         TRACE_STRUCT(
>                 TRACE_FIELD(pid_t, prev_pid, prev->pid)
>                 TRACE_FIELD(int, prev_prio, prev->prio)
>                 TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
>                                     next_comm,
>                                     TPCMD(memcpy(TRACE_ENTRY->next_comm,
>                                                  next->comm,
>                                                  TASK_COMM_LEN)))
>                 TRACE_FIELD(pid_t, next_pid, next->pid)
>                 TRACE_FIELD(int, next_prio, next->prio)
>         ),
>         TPRAWFMT("prev %d:%d ==> next %s:%d:%d")
>         );

I'm not quite sure how to do strings with those. The IRQ tracepoints
cheat and omit the string, and the sched tracepoints cheat and use this
static sized comm array.