1PERF-DIFF(1) perf Manual PERF-DIFF(1)
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6 perf-diff - Read perf.data files and display the differential profile
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9 perf diff [baseline file] [data file1] [[data file2] ... ]
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12 This command displays the performance difference amongst two or more
13 perf.data files captured via perf record.
14 If no parameters are passed it will assume perf.data.old and perf.data.
16 The differential profile is displayed only for events matching both
18 specified perf.data files.
19 If no parameters are passed the samples will be sorted by dso and
21 symbol. As the perf.data files could come from different binaries, the
22 symbols addresses could vary. So perf diff is based on the comparison
23 of the files and symbols name.
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26 -D, --dump-raw-trace
27 Dump raw trace in ASCII.
28 --kallsyms=<file>
30 kallsyms pathname
31 -m, --modules
33 Load module symbols. WARNING: use only with -k and LIVE kernel
34 -d, --dsos=
36 Only consider symbols in these dsos. CSV that understands
37 file://filename entries. This option will affect the percentage of
38 the Baseline/Delta column. See --percentage for more info.
39 -C, --comms=
41 Only consider symbols in these comms. CSV that understands
42 file://filename entries. This option will affect the percentage of
43 the Baseline/Delta column. See --percentage for more info.
44 -S, --symbols=
46 Only consider these symbols. CSV that understands file://filename
47 entries. This option will affect the percentage of the
48 Baseline/Delta column. See --percentage for more info.
49 -s, --sort=
51 Sort by key(s): pid, comm, dso, symbol, cpu, parent, srcline.
52 Please see description of --sort in the perf-report man page.
53 -t, --field-separator=
55 Use a special separator character and don’t pad with spaces,
56 replacing all occurrences of this separator in symbol names (and
57 other output) with a . character, that thus it’s the only non
58 valid separator.
59 -v, --verbose
61 Be verbose, for instance, show the raw counts in addition to the
62 diff.
63 -q, --quiet
65 Do not show any message. (Suppress -v)
66 -f, --force
68 Don’t do ownership validation.
69 --symfs=<directory>
71 Look for files with symbols relative to this directory.
72 -b, --baseline-only
74 Show only items with match in baseline.
75 -c, --compute
77 Differential computation selection - delta, ratio, wdiff, delta-abs
78 (default is delta-abs). Default can be changed using diff.compute
79 config option. See COMPARISON METHODS section for more info.
80 -p, --period
82 Show period values for both compared hist entries.
83 -F, --formula
85 Show formula for given computation.
86 -o, --order
88 Specify compute sorting column number. 0 means sorting by baseline
89 overhead and 1 (default) means sorting by computed value of column
90 1 (data from the first file other base baseline). Values more than
91 1 can be used only if enough data files are provided. The default
92 value can be set using the diff.order config option.
93 --percentage
95 Determine how to display the overhead percentage of filtered
96 entries. Filters can be applied by --comms, --dsos and/or --symbols
97 options.
98 "relative" means it's relative to filtered entries only so that the
100 sum of shown entries will be always 100%. "absolute" means it retains
101 the original value before and after the filter is applied.
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104 The comparison is governed by the baseline file. The baseline perf.data
105 file is iterated for samples. All other perf.data files specified on
106 the command line are searched for the baseline sample pair. If the pair
107 is found, specified computation is made and result is displayed.
108 All samples from non-baseline perf.data files, that do not match any
110 baseline entry, are displayed with empty space within baseline column
111 and possible computation results (delta) in their related column.
112 Example files samples: - file A with samples f1, f2, f3, f4, f6 - file
114 B with samples f2, f4, f5 - file C with samples f1, f2, f5
115 Example output: x - computation takes place for pair b - baseline
117 sample percentage
118 · perf diff A B C
120 baseline/A compute/B compute/C samples
122 ---------------------------------------
123 b x f1
124 b x x f2
125 b f3
126 b x f4
127 b f6
128 x x f5
129 · perf diff B A C
131 baseline/B compute/A compute/C samples
133 ---------------------------------------
134 b x x f2
135 b x f4
136 b x f5
137 x x f1
138 x f3
139 x f6
140 · perf diff C B A
142 baseline/C compute/B compute/A samples
144 ---------------------------------------
145 b x f1
146 b x x f2
147 b x f5
148 x f3
149 x x f4
150 x f6
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153 delta
154 If specified the Delta column is displayed with value d computed as:
155 d = A->period_percent - B->period_percent
157 with: - A/B being matching hist entry from data/baseline file specified
159 (or perf.data/perf.data.old) respectively.
160 · period_percent being the % of the hist entry period value within
162 single data file
163 · with filtering by -C, -d and/or -S, period_percent might be changed
165 relative to how entries are filtered. Use --percentage=absolute to
166 prevent such fluctuation.
167 delta-abs
169 Same as 'delta` method, but sort the result with the absolute values.
170 ratio
172 If specified the Ratio column is displayed with value r computed as:
173 r = A->period / B->period
175 with: - A/B being matching hist entry from data/baseline file specified
177 (or perf.data/perf.data.old) respectively.
178 · period being the hist entry period value
180 wdiff:WEIGHT-B,WEIGHT-A
182 If specified the Weighted diff column is displayed with value d
183 computed as:
184 d = B->period * WEIGHT-A - A->period * WEIGHT-B
186 · A/B being matching hist entry from data/baseline file specified (or
188 perf.data/perf.data.old) respectively.
189 · period being the hist entry period value
191 · WEIGHT-A/WEIGHT-B being user supplied weights in the the -c option
193 behind : separator like -c wdiff:1,2.
194 · WEIGHT-A being the weight of the data file
196 · WEIGHT-B being the weight of the baseline data file
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200 perf-record(1), perf-report(1)
201perf 06/18/2019 PERF-DIFF(1)