From: Theodore Ts'o Date: Sat, 11 Apr 2009 19:51:19 +0000 (-0400) Subject: tracing: Add documentation for the power tracer X-Git-Tag: firefly_0821_release~13991^2~181 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=56c49951747f250d8398582509e02ae5ce1d36d1;p=firefly-linux-kernel-4.4.55.git tracing: Add documentation for the power tracer Signed-off-by: "Theodore Ts'o" Acked-by: Arjan van de Ven Cc: Frederic Weisbecker Cc: Steven Rostedt LKML-Reference: <1239479479-2603-4-git-send-email-tytso@mit.edu> Signed-off-by: Ingo Molnar --- diff --git a/Documentation/trace/power.txt b/Documentation/trace/power.txt new file mode 100644 index 000000000000..cd805e16dc27 --- /dev/null +++ b/Documentation/trace/power.txt @@ -0,0 +1,17 @@ +The power tracer collects detailed information about C-state and P-state +transitions, instead of just looking at the high-level "average" +information. + +There is a helper script found in scrips/tracing/power.pl in the kernel +sources which can be used to parse this information and create a +Scalable Vector Graphics (SVG) picture from the trace data. + +To use this tracer: + + echo 0 > /sys/kernel/debug/tracing/tracing_enabled + echo power > /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/tracing/power.pl > out.sv