Re: perf_counter: hook up the tracepoint events

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Tue, 2009-07-28 at 21:01 -0400, Jeff Garzik wrote:
> Peter Zijlstra wrote:
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 8a38443..761129a 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -945,6 +945,11 @@ config PERF_COUNTERS
> >  
> >  	  Say Y if unsure.
> >  
> > +config EVENT_PROFILE
> > +	bool "Tracepoint profile sources"
> > +	depends on PERF_COUNTERS && EVENT_TRACER
> > +	default y
> > +
> >  endmenu
> 
> Adding help text would be... helpful.   :)
> 
> The net result in this case was the addition of a completely-unexplained 
> Kconfig option late in 2.6.31-rc.
> 
> Maybe the x86 maintainers could help see that they don't push 
> unexplained Kconfig options upstream -- particularly ones we are asked 
> to enable by default?

You're right. Johannes Berg made the same complaint yesterday.

Is the below any good?

---
Subject: perf_counter: Add help text to CONFIG_EVENT_PROFILE

Explain what tracepoint profile sources is about.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 init/Kconfig |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 13473ac..ffae67c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -957,6 +957,12 @@ config EVENT_PROFILE
 	bool "Tracepoint profile sources"
 	depends on PERF_COUNTERS && EVENT_TRACING
 	default y
+	help
+	 Allow the use of tracepoints as software performance counters.
+
+	 When this is enabled, you can create perf counters based on
+	 tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
+	 found in debugfs://tracing/events/*/*/id.
 
 endmenu