tools/power turbostat: add --out option for saving output in a file
By default...
Turbostat --debug gconfiguration info goes to stderr.
In FORK mode, turbostat statistics go to stderr.
In PERIODIC mode, turbostat statistics go to stdout.
These defaults do not change, but an option "--out file"
will send all output above only to the specified file.
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/tools/power/x86/turbostat/turbostat.8 b/tools/power/x86/turbostat/turbostat.8
index 7771eea..89a55d5 100644
--- a/tools/power/x86/turbostat/turbostat.8
+++ b/tools/power/x86/turbostat/turbostat.8
@@ -36,6 +36,9 @@
.PP
\fB--interval seconds\fP overrides the default 5.0 second measurement interval.
.PP
+\fB--out output_file\fP turbostat output is written to the specified output_file.
+The file is truncated if it already exists, and it is created if it does not exist.
+.PP
\fB--help\fP displays usage for the most common parameters.
.PP
\fB--Joules\fP displays energy in Joules, rather than dividing Joules by time to print power in Watts.
@@ -83,10 +86,11 @@
\fBRAM_%\fP percent of the interval that RAPL throttling was active on DRAM.
.fi
.PP
-.SH EXAMPLE
+.SH PERIODIC EXAMPLE
Without any parameters, turbostat displays statistics ever 5 seconds.
-(override interval with "-i sec" option, or specify a command
-for turbostat to fork).
+Periodic output goes to stdout, by default, unless --out is used to specify an output file.
+The 5-second interval can be changed with th "-i sec" option.
+Or a command may be specified as in "FORK EXAMPLE" below.
.nf
[root@hsw]# ./turbostat
CPU Avg_MHz Busy% Bzy_MHz TSC_MHz
@@ -171,7 +175,9 @@
See the field definitions above.
.SH FORK EXAMPLE
If turbostat is invoked with a command, it will fork that command
-and output the statistics gathered when the command exits.
+and output the statistics gathered after the command exits.
+In this case, turbostat output goes to stderr, by default.
+Output can instead be saved to a file using the --out option.
eg. Here a cycle soaker is run on 1 CPU (see %c0) for a few seconds
until ^C while the other CPUs are mostly idle: