On Wed, 8 Jul 2015 14:31:48 +0200
Peter Zijlstra <[email protected]> wrote:
> On Tue, Jul 07, 2015 at 06:10:43PM +0800, Chunyan Zhang wrote:
> > Add the function 'trace_event_stm_output_##call' for printing events
> > trace log into STM blocks.
> >
> > This patch also adds a function call at where the events have been
> > committed to ring buffer to export the trace event information to
> > STM blocks.
>
> So then you have two copies of the data, why that? Would a scheme were
> data either goes to the STM or the regular buffer not make much more
> sense?
>
> > +++ b/include/trace/perf.h
> > @@ -175,6 +175,7 @@ trace_event_raw_event_##call(void *__data, proto)
> > \
> > { assign; } \
> > \
> > trace_event_buffer_commit(&fbuffer); \
> > + trace_event_stm_log(&fbuffer); \
>
> This makes every trace event slower.
Of course this could use a jump label.
But I agree, I think a switch to which buffer it should be sent to is
better. I could come up with a way to make the buffer more generic, and
have it switch between where the event is recorded.
-- Steve
>
> > }
> > /*
> > * The ftrace_test_probe is compiled out, it is only here as a build time
> > check
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