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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | COMPARISON | COMPARISON METHODS | SEE ALSO | COLOPHON |
PERF-DIFF(1) perf Manual PERF-DIFF(1)
perf-diff - Read perf.data files and display the differential profile
perf diff [baseline file] [data file1] [[data file2] ... ]
This command displays the performance difference amongst two or more
perf.data files captured via perf record.
If no parameters are passed it will assume perf.data.old and
perf.data.
The differential profile is displayed only for events matching both
specified perf.data files.
If no parameters are passed the samples will be sorted by dso and
symbol. As the perf.data files could come from different binaries,
the symbols addresses could vary. So perf diff is based on the
comparison of the files and symbols name.
-D, --dump-raw-trace
Dump raw trace in ASCII.
--kallsyms=<file>
kallsyms pathname
-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.
-q, --quiet
Do not show any message. (Suppress -v)
-f, --force
Don’t do ownership validation.
--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,
delta-abs (default is delta-abs). Default can be changed using
diff.compute config option. 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. 0 means sorting by
baseline overhead and 1 (default) means sorting by computed value
of column 1 (data from the first file other base baseline).
Values more than 1 can be used only if enough data files are
provided. The default value can be set using the diff.order
config option.
--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.
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.
All samples from non-baseline perf.data files, that do not match any
baseline entry, are displayed with empty space within baseline column
and possible computation results (delta) in their related column.
Example files samples: - file A with samples f1, f2, f3, f4, f6 -
file B with samples f2, f4, f5 - file C with samples f1, f2, f5
Example output: x - computation takes place for pair b - baseline
sample percentage
· 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
delta
If specified the Delta column is displayed with value d computed as:
d = A->period_percent - B->period_percent
with: - A/B being matching hist entry from data/baseline file
specified (or perf.data/perf.data.old) respectively.
· 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.
delta-abs
Same as 'delta` method, but sort the result with the absolute values.
ratio
If specified the Ratio column is displayed with value r computed as:
r = A->period / B->period
with: - 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
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 supplied weights in the the -c
option behind : separator like -c wdiff:1,2.
· WEIGHT-A being the weight of the data file
· WEIGHT-B being the weight of the baseline data file
perf-record(1), perf-report(1)
This page is part of the perf (Performance analysis tools for Linux
(in Linux source tree)) project. Information about the project can
be found at ⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩. If
you have a bug report for this manual page, send it to
linux-kernel@vger.kernel.org. This page was obtained from the
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⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩ on
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ual page), send a mail to man-pages@man7.org
perf 03/12/2017 PERF-DIFF(1)
Pages that refer to this page: perf-kvm(1)