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, 7 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3abd645e8af2..4c453778a6ab 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -28,6 +28,7 @@ enum trace_type {
         TRACE_FN_RET,
         TRACE_USER_STACK,
         TRACE_BTS,
+        TRACE_POWER,
 
         __TRACE_LAST_TYPE
 };
@@ -160,6 +161,11 @@ struct bts_entry {
         unsigned long           to;
 };
 
+struct trace_power {
+        struct trace_entry      ent;
+        struct power_trace      state_data;
+};
+
 /*
  * trace_flag_type is an enumeration that holds different
  * states when a trace occurs. These are:
@@ -266,6 +272,7 @@ extern void __ftrace_bad_type(void);
                 IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
                 IF_ASSIGN(var, ent, struct ftrace_ret_entry, TRACE_FN_RET);\
                 IF_ASSIGN(var, ent, struct bts_entry, TRACE_BTS);\
+                IF_ASSIGN(var, ent, struct trace_power, TRACE_POWER); \
                 __ftrace_bad_type();                                    \
         } while (0)