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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>
This commit is contained in:
Theodore Ts'o 2009-04-11 15:51:19 -04:00 committed by Ingo Molnar
parent 5cb3d1d9d3
commit 56c4995174
1 changed files with 17 additions and 0 deletions
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17
Documentation/trace/power.txt Normal file
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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