Re: [PATCH 2/4] locking: Apply contention tracepoints in the slow path

Namhyung Kim
2022-03-01T18:14:40Z

Hi Steve,

On Tue, Mar 1, 2022 at 6:45 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Tue, 1 Mar 2022 10:03:54 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> > index 8555c4efe97c..18b9f4bf6f34 100644
> > --- a/kernel/locking/rtmutex.c
> > +++ b/kernel/locking/rtmutex.c
> > @@ -1579,6 +1579,8 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
> >
> > set_current_state(state);
> >
> > + trace_contention_begin(lock, _RET_IP_, LCB_F_RT);
>
> I guess one issue with this is that _RET_IP_ will return the rt_mutex
> address if this is not inlined, making the _RET_IP_ rather useless.
>
> Now, if we can pass the _RET_IP_ into __rt_mutex_slowlock() then we could
> reference that.

Right, that's what I did in patch 03 and 04 for mutex and rwsem.
But I forgot to update rt_mutex, will fix.

Thanks,
Namhyung