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 -f, --force
65 Don’t complain, do it.
66 --symfs=<directory>
68 Look for files with symbols relative to this directory.
69 -b, --baseline-only
71 Show only items with match in baseline.
72 -c, --compute
74 Differential computation selection - delta,ratio,wdiff (default is
75 delta). See COMPARISON METHODS section for more info.
76 -p, --period
78 Show period values for both compared hist entries.
79 -F, --formula
81 Show formula for given computation.
82 -o, --order
84 Specify compute sorting column number.
85 --percentage
87 Determine how to display the overhead percentage of filtered
88 entries. Filters can be applied by --comms, --dsos and/or --symbols
89 options.
90 "relative" means it´s relative to filtered entries only so that the
92 sum of shown entries will be always 100%. "absolute" means it retains
93 the original value before and after the filter is applied.
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96 The comparison is governed by the baseline file. The baseline perf.data
97 file is iterated for samples. All other perf.data files specified on
98 the command line are searched for the baseline sample pair. If the pair
99 is found, specified computation is made and result is displayed.
100 All samples from non-baseline perf.data files, that do not match any
102 baseline entry, are displayed with empty space within baseline column
103 and possible computation results (delta) in their related column.
104 Example files samples: - file A with samples f1, f2, f3, f4, f6 - file
106 B with samples f2, f4, f5 - file C with samples f1, f2, f5
107 Example output: x - computation takes place for pair b - baseline
109 sample percentage
110 · perf diff A B C
112 baseline/A compute/B compute/C samples
114 ---------------------------------------
115 b x f1
116 b x x f2
117 b f3
118 b x f4
119 b f6
120 x x f5
121 · perf diff B A C
123 baseline/B compute/A compute/C samples
125 ---------------------------------------
126 b x x f2
127 b x f4
128 b x f5
129 x x f1
130 x f3
131 x f6
132 · perf diff C B A
134 baseline/C compute/B compute/A samples
136 ---------------------------------------
137 b x f1
138 b x x f2
139 b x f5
140 x f3
141 x x f4
142 x f6
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145 delta
146 If specified the Delta column is displayed with value d computed as:
147 d = A->period_percent - B->period_percent
149 with: - A/B being matching hist entry from data/baseline file specified
151 (or perf.data/perf.data.old) respectively.
152 · period_percent being the % of the hist entry period value within
154 single data file
155 · with filtering by -C, -d and/or -S, period_percent might be changed
157 relative to how entries are filtered. Use --percentage=absolute to
158 prevent such fluctuation.
159 ratio
161 If specified the Ratio column is displayed with value r computed as:
162 r = A->period / B->period
164 with: - A/B being matching hist entry from data/baseline file specified
166 (or perf.data/perf.data.old) respectively.
167 · period being the hist entry period value
169 wdiff:WEIGHT-B,WEIGHT-A
171 If specified the Weighted diff column is displayed with value d
172 computed as:
173 d = B->period * WEIGHT-A - A->period * WEIGHT-B
175 · A/B being matching hist entry from data/baseline file specified (or
177 perf.data/perf.data.old) respectively.
178 · period being the hist entry period value
180 · WEIGHT-A/WEIGHT-B being user supplied weights in the the -c option
182 behind : separator like -c wdiff:1,2.
183 · WEIGHT-A being the weight of the data file
185 · WEIGHT-B being the weight of the baseline data file
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189 perf-record(1), perf-report(1)
190perf 06/18/2019 PERF-DIFF(1)