Messages in this thread | | | Date | Mon, 27 Oct 2008 16:13:21 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: PATCH] ftrace: Add a C/P state tracer to help power optimization |
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On Mon, 27 Oct 2008, Frank Ch. Eigler wrote:
> > Arjan van de Ven <arjan@infradead.org> writes: > > > [...] > > --- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c > > +++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c > > [...] > > @@ -427,6 +429,8 @@ static int acpi_cpufreq_target(struct cpufreq_policy *policy, > > } > > } > > > > + trace_power_mark(&it, POWER_PSTATE, next_perf_state); > > + > > switch (data->cpu_feature) { > > case SYSTEM_INTEL_MSR_CAPABLE: > > cmd.type = SYSTEM_INTEL_MSR_CAPABLE; > > [...] > > Is there some reason that this doesn't use tracepoints instead > of such a single-backend hook?
Yeah, this should be converted to a trace_point. See include/trace/sched.h for examples.
The users are in kernel/sched.c. Just add "trace_" in front of the names to find the users. Then you can look at kernel/trace/trace_sched_switch.c to see an example on how to hook into it.
-- Steve
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