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SubjectRe: [PATCH][RFC] ftrace: function oprofiler

On Sat, 25 Oct 2008, Fr?d?ric Weisbecker wrote:

> Hi Steven,
>
> 2008/10/25 Steven Rostedt <rostedt@goodmis.org>:
> > # cat /debug/tracing/ftrace_profile | sort -brn | head -20
> > 280075 : __rcu_read_unlock+0xb/0xa2
> > 280065 : __rcu_read_lock+0x11/0xb3
>
> The rcu function are on top of this profile. May be it's because you use
> rcu when you touch your hash table.
> Wouldn't be interesting to disable the counter adding for these
> functions when they
> are used at this time?

It is disabled at that time. Look at the trace_active variable. If it
is already set for that CPU, the counter is disabled.

But! That said. I need to make the count an atomic inc. There's nothing
protecting it from SMP.

>
> > +config FUNCTION_PROFILER
> > + bool "Trace max stack"
>
> Copy-paste error? :-)

Hehe, yeah. This and the above bug are both the cause of writing this
after midnight. That is exactly why I said this is not ready for inclusion
;-)

-- Steve



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