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authorTheodore Ts'o <tytso@mit.edu>2009-04-11 15:51:19 -0400
committerIngo Molnar <mingo@elte.hu>2009-04-12 14:51:42 +0200
commit56c49951747f250d8398582509e02ae5ce1d36d1 (patch)
tree24ce4afcf9bb96593f6fe8afb488f0e38b04bfe8 /Documentation/trace
parent5cb3d1d9d34ac04bcaa2034139345b2a5fea54c1 (diff)
tracing: Add documentation for the power tracer
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <srostedt@redhat.com> LKML-Reference: <1239479479-2603-4-git-send-email-tytso@mit.edu> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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-rw-r--r--Documentation/trace/power.txt17
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diff --git a/Documentation/trace/power.txt b/Documentation/trace/power.txt
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+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