tracing: add "power-tracer": C/P state tracer to help power optimization

Impact: new "power-tracer" ftrace plugin

This patch adds a C/P-state ftrace plugin that will generate
detailed statistics about the C/P-states that are being used,
so that we can look at detailed decisions that the C/P-state
code is making, rather than the too high level "average"
that we have today.

An example way of using this is:

 mount -t debugfs none /sys/kernel/debug
 echo cstate > /sys/kernel/debug/tracing/current_tracer
 echo 1 > /sys/kernel/debug/tracing/tracing_enabled
 sleep 1
 echo 0 > /sys/kernel/debug/tracing/tracing_enabled
 cat /sys/kernel/debug/tracing/trace | perl scripts/trace/cstate.pl > out.svg

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 0 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 620feadff67a..d151aab48ed6 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -217,6 +217,17 @@ config BRANCH_TRACER
 
           Say N if unsure.
 
+config POWER_TRACER
+        bool "Trace power consumption behavior"
+        depends on DEBUG_KERNEL
+        depends on X86
+        select TRACING
+        help
+          This tracer helps developers to analyze and optimize the kernels
+          power management decisions, specifically the C-state and P-state
+          behavior.
+
+
 config STACK_TRACER
         bool "Trace max stack"
         depends on HAVE_FUNCTION_TRACER