table of contents
PERF-DIFF(1) | perf Manual | PERF-DIFF(1) |
NAME¶
perf-diff - Read perf.data files and display the differential profile
SYNOPSIS¶
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.
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.
OPTIONS¶
-D, --dump-raw-trace
--kallsyms=<file>
-m, --modules
-d, --dsos=
-C, --comms=
-S, --symbols=
-s, --sort=
-t, --field-separator=
-v, --verbose
-q, --quiet
-f, --force
--symfs=<directory>
-b, --baseline-only
-c, --compute
-p, --period
-F, --formula
-o, --order
--percentage
"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.
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
baseline/A compute/B compute/C samples --------------------------------------- b x f1 b x x f2 b f3 b x f4 b f6
x x f5
baseline/B compute/A compute/C samples --------------------------------------- b x x f2 b x f4 b x f5
x x f1
x f3
x f6
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
with: - A/B being matching hist entry from data/baseline file specified (or perf.data/perf.data.old) respectively.
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.
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
SEE ALSO¶
06/04/2024 | perf |