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PERF_3.16-DIFF(1) | perf Manual | PERF_3.16-DIFF(1) |
NAME¶
perf-diff - Read perf.data files and display the differential profileSYNOPSIS¶
perf diff [baseline file] [data file1] [[data file2] ... ]
DESCRIPTION¶
This command displays the performance difference amongst two or more perf.data files captured via perf record.OPTIONS¶
-D, --dump-raw-traceDump raw trace in ASCII.
-m, --modules
Load module symbols. WARNING: use only with -k
and LIVE kernel
-d, --dsos=
Only consider symbols in these dsos. CSV that
understands file://filename entries. This option will affect the
percentage of the Baseline/Delta column. See --percentage for more info.
-C, --comms=
Only consider symbols in these comms. CSV that
understands file://filename entries. This option will affect the
percentage of the Baseline/Delta column. See --percentage for more info.
-S, --symbols=
Only consider these symbols. CSV that
understands file://filename entries. This option will affect the
percentage of the Baseline/Delta column. See --percentage for more info.
-s, --sort=
Sort by key(s): pid, comm, dso, symbol, cpu,
parent, srcline. Please see description of --sort in the perf-report man
page.
-t, --field-separator=
Use a special separator character and
don’t pad with spaces, replacing all occurrences of this separator in
symbol names (and other output) with a . character, that thus
it’s the only non valid separator.
-v, --verbose
Be verbose, for instance, show the raw counts
in addition to the diff.
-f, --force
Don’t complain, do it.
--symfs=<directory>
Look for files with symbols relative to this
directory.
-b, --baseline-only
Show only items with match in baseline.
-c, --compute
Differential computation selection -
delta,ratio,wdiff (default is delta). See COMPARISON METHODS section for more
info.
-p, --period
Show period values for both compared hist
entries.
-F, --formula
Show formula for given computation.
-o, --order
Specify compute sorting column number.
--percentage
Determine how to display the overhead
percentage of filtered entries. Filters can be applied by --comms, --dsos
and/or --symbols options.
"relative" means it's relative to filtered entries only so that the sum of shown entries will be always 100%. "absolute" means it retains the original value before and after the filter is applied.
COMPARISON¶
The comparison is governed by the baseline file. The baseline perf.data file is iterated for samples. All other perf.data files specified on the command line are searched for the baseline sample pair. If the pair is found, specified computation is made and result is displayed.•perf diff A B C
baseline/A compute/B compute/C samples --------------------------------------- b x f1 b x x f2 b f3 b x f4 b f6 x x f5
•perf diff B A C
baseline/B compute/A compute/C samples --------------------------------------- b x x f2 b x f4 b x f5 x x f1 x f3 x f6
•perf diff C B A
baseline/C compute/B compute/A samples --------------------------------------- b x f1 b x x f2 b x f5 x f3 x x f4 x f6
COMPARISON METHODS¶
delta¶
If specified the Delta column is displayed with value d computed as:d = A->period_percent - B->period_percent
•period_percent being the % of the hist
entry period value within single data file
•with filtering by -C, -d and/or -S,
period_percent might be changed relative to how entries are filtered. Use
--percentage=absolute to prevent such fluctuation.
ratio¶
If specified the Ratio column is displayed with value r computed as:r = A->period / B->period
•period being the hist entry period
value
wdiff:WEIGHT-B,WEIGHT-A¶
If specified the Weighted diff column is displayed with value d computed as:d = B->period * WEIGHT-A - A->period * WEIGHT-B
•A/B being matching hist entry from
data/baseline file specified (or perf.data/perf.data.old) respectively.
•period being the hist entry period
value
•WEIGHT-A/WEIGHT-B being user suplied
weights in the the -c option behind : separator like -c
wdiff:1,2.
•WIEGHT-A being the weight of the data
file
•WIEGHT-B being the weight of the
baseline data file
SEE ALSO¶
perf_3.16-record(1), perf_3.16-report(1)02/24/2016 | perf |