1 perf-diff(1) 1 perf-diff(1)
2 ============ 2 ============
3 3
4 NAME 4 NAME
5 ---- 5 ----
6 perf-diff - Read perf.data files and display t 6 perf-diff - Read perf.data files and display the differential profile
7 7
8 SYNOPSIS 8 SYNOPSIS
9 -------- 9 --------
10 [verse] 10 [verse]
11 'perf diff' [baseline file] [data file1] [[dat 11 'perf diff' [baseline file] [data file1] [[data file2] ... ]
12 12
13 DESCRIPTION 13 DESCRIPTION
14 ----------- 14 -----------
15 This command displays the performance differen 15 This command displays the performance difference amongst two or more perf.data
16 files captured via perf record. 16 files captured via perf record.
17 17
18 If no parameters are passed it will assume per 18 If no parameters are passed it will assume perf.data.old and perf.data.
19 19
20 The differential profile is displayed only for 20 The differential profile is displayed only for events matching both
21 specified perf.data files. 21 specified perf.data files.
22 22
23 If no parameters are passed the samples will b 23 If no parameters are passed the samples will be sorted by dso and symbol.
24 As the perf.data files could come from differe 24 As the perf.data files could come from different binaries, the symbols addresses
25 could vary. So perf diff is based on the compa 25 could vary. So perf diff is based on the comparison of the files and
26 symbols name. 26 symbols name.
27 27
28 OPTIONS 28 OPTIONS
29 ------- 29 -------
30 -D:: 30 -D::
31 --dump-raw-trace:: 31 --dump-raw-trace::
32 Dump raw trace in ASCII. 32 Dump raw trace in ASCII.
33 33
34 --kallsyms=<file>:: 34 --kallsyms=<file>::
35 kallsyms pathname 35 kallsyms pathname
36 36
37 -m:: 37 -m::
38 --modules:: 38 --modules::
39 Load module symbols. WARNING: use only 39 Load module symbols. WARNING: use only with -k and LIVE kernel
40 40
41 -d:: 41 -d::
42 --dsos=:: 42 --dsos=::
43 Only consider symbols in these dsos. C 43 Only consider symbols in these dsos. CSV that understands
44 file://filename entries. This option 44 file://filename entries. This option will affect the percentage
45 of the Baseline/Delta column. See --p 45 of the Baseline/Delta column. See --percentage for more info.
46 46
47 -C:: 47 -C::
48 --comms=:: 48 --comms=::
49 Only consider symbols in these comms. 49 Only consider symbols in these comms. CSV that understands
50 file://filename entries. This option 50 file://filename entries. This option will affect the percentage
51 of the Baseline/Delta column. See --p 51 of the Baseline/Delta column. See --percentage for more info.
52 52
53 -S:: 53 -S::
54 --symbols=:: 54 --symbols=::
55 Only consider these symbols. CSV that 55 Only consider these symbols. CSV that understands
56 file://filename entries. This option 56 file://filename entries. This option will affect the percentage
57 of the Baseline/Delta column. See --p 57 of the Baseline/Delta column. See --percentage for more info.
58 58
59 -s:: 59 -s::
60 --sort=:: 60 --sort=::
61 Sort by key(s): pid, comm, dso, symbol 61 Sort by key(s): pid, comm, dso, symbol, cpu, parent, srcline.
62 Please see description of --sort in th 62 Please see description of --sort in the perf-report man page.
63 63
64 -t:: 64 -t::
65 --field-separator=:: 65 --field-separator=::
66 66
67 Use a special separator character and 67 Use a special separator character and don't pad with spaces, replacing
68 all occurrences of this separator in s 68 all occurrences of this separator in symbol names (and other output)
69 with a '.' character, that thus it's t 69 with a '.' character, that thus it's the only non valid separator.
70 70
71 -v:: 71 -v::
72 --verbose:: 72 --verbose::
73 Be verbose, for instance, show the raw 73 Be verbose, for instance, show the raw counts in addition to the
74 diff. 74 diff.
75 75
76 -q:: <<
77 --quiet:: <<
78 Do not show any warnings or messages. <<
79 <<
80 -f:: 76 -f::
81 --force:: 77 --force::
82 Don't do ownership validation. 78 Don't do ownership validation.
83 79
84 --symfs=<directory>:: 80 --symfs=<directory>::
85 Look for files with symbols relative t 81 Look for files with symbols relative to this directory.
86 82
87 -b:: 83 -b::
88 --baseline-only:: 84 --baseline-only::
89 Show only items with match in baseline 85 Show only items with match in baseline.
90 86
91 -c:: 87 -c::
92 --compute:: 88 --compute::
93 Differential computation selection - d !! 89 Differential computation selection - delta,ratio,wdiff (default is delta).
94 delta-abs (default is delta-abs). Def !! 90 See COMPARISON METHODS section for more info.
95 diff.compute config option. See COMPA <<
96 more info. <<
97 <<
98 --cycles-hist:: <<
99 Report a histogram and the standard de <<
100 It can help us to judge if the reporte <<
101 not. This option should be used with ' <<
102 91
103 -p:: 92 -p::
104 --period:: 93 --period::
105 Show period values for both compared h 94 Show period values for both compared hist entries.
106 95
107 -F:: 96 -F::
108 --formula:: 97 --formula::
109 Show formula for given computation. 98 Show formula for given computation.
110 99
111 -o:: 100 -o::
112 --order:: 101 --order::
113 Specify compute sorting column number. !! 102 Specify compute sorting column number.
114 overhead and 1 (default) means sorting <<
115 (data from the first file other base ba <<
116 can be used only if enough data files a <<
117 The default value can be set using the <<
118 103
119 --percentage:: 104 --percentage::
120 Determine how to display the overhead 105 Determine how to display the overhead percentage of filtered entries.
121 Filters can be applied by --comms, --d 106 Filters can be applied by --comms, --dsos and/or --symbols options.
122 107
123 "relative" means it's relative to filt 108 "relative" means it's relative to filtered entries only so that the
124 sum of shown entries will be always 10 109 sum of shown entries will be always 100%. "absolute" means it retains
125 the original value before and after th 110 the original value before and after the filter is applied.
126 111
127 --time:: <<
128 Analyze samples within given time wind <<
129 percent with multiple time ranges. Tim <<
130 or 'a%-b%,c%-%d,...'. <<
131 <<
132 For example: <<
133 <<
134 Select the second 10% time slice to di <<
135 <<
136 perf diff --time 10%/2 <<
137 <<
138 Select from 0% to 10% time slice to di <<
139 <<
140 perf diff --time 0%-10% <<
141 <<
142 Select the first and the second 10% ti <<
143 <<
144 perf diff --time 10%/1,10%/2 <<
145 <<
146 Select from 0% to 10% and 30% to 40% s <<
147 <<
148 perf diff --time 0%-10%,30%-40% <<
149 <<
150 It also supports analyzing samples wit <<
151 <start>,<stop>. Times have the format <<
152 is not given (i.e. time string is ',x. <<
153 the beginning of the file. If stop tim <<
154 string is 'x.y,') then analysis goes t <<
155 Multiple ranges can be separated by sp <<
156 to be quoted e.g. --time "1234.567,123 <<
157 Time string is'a1.b1,c1.d1:a2.b2,c2.d2 <<
158 for different perf.data files. <<
159 <<
160 For example, we get the timestamp info <<
161 <<
162 perf script -i perf.data.old <<
163 mgen 13940 [000] 3946.361400: ... <<
164 <<
165 perf script -i perf.data <<
166 mgen 13940 [000] 3971.150589 ... <<
167 <<
168 perf diff --time 3946.361400,:3971.1 <<
169 <<
170 It analyzes the perf.data.old from the <<
171 the end of perf.data.old and analyzes <<
172 timestamp 3971.150589 to the end of pe <<
173 <<
174 --cpu:: Only diff samples for the list of CPUs <<
175 be provided as a comma-separated list <<
176 CPUs are specified with -: 0-2. Defaul <<
177 CPUs. <<
178 <<
179 --pid=:: <<
180 Only diff samples for given process ID <<
181 <<
182 --tid=:: <<
183 Only diff samples for given thread ID <<
184 <<
185 --stream:: <<
186 Enable hot streams comparison. Stream <<
187 aggregated by the branch records from <<
188 <<
189 COMPARISON 112 COMPARISON
190 ---------- 113 ----------
191 The comparison is governed by the baseline fil 114 The comparison is governed by the baseline file. The baseline perf.data
192 file is iterated for samples. All other perf.d 115 file is iterated for samples. All other perf.data files specified on
193 the command line are searched for the baseline 116 the command line are searched for the baseline sample pair. If the pair
194 is found, specified computation is made and re 117 is found, specified computation is made and result is displayed.
195 118
196 All samples from non-baseline perf.data files, 119 All samples from non-baseline perf.data files, that do not match any
197 baseline entry, are displayed with empty space 120 baseline entry, are displayed with empty space within baseline column
198 and possible computation results (delta) in th 121 and possible computation results (delta) in their related column.
199 122
200 Example files samples: 123 Example files samples:
201 - file A with samples f1, f2, f3, f4, f6 124 - file A with samples f1, f2, f3, f4, f6
202 - file B with samples f2, f4, f5 125 - file B with samples f2, f4, f5
203 - file C with samples f1, f2, f5 126 - file C with samples f1, f2, f5
204 127
205 Example output: 128 Example output:
206 x - computation takes place for pair 129 x - computation takes place for pair
207 b - baseline sample percentage 130 b - baseline sample percentage
208 131
209 - perf diff A B C 132 - perf diff A B C
210 133
211 baseline/A compute/B compute/C samples 134 baseline/A compute/B compute/C samples
212 --------------------------------------- 135 ---------------------------------------
213 b x f1 136 b x f1
214 b x x f2 137 b x x f2
215 b f3 138 b f3
216 b x f4 139 b x f4
217 b f6 140 b f6
218 x x f5 141 x x f5
219 142
220 - perf diff B A C 143 - perf diff B A C
221 144
222 baseline/B compute/A compute/C samples 145 baseline/B compute/A compute/C samples
223 --------------------------------------- 146 ---------------------------------------
224 b x x f2 147 b x x f2
225 b x f4 148 b x f4
226 b x f5 149 b x f5
227 x x f1 150 x x f1
228 x f3 151 x f3
229 x f6 152 x f6
230 153
231 - perf diff C B A 154 - perf diff C B A
232 155
233 baseline/C compute/B compute/A samples 156 baseline/C compute/B compute/A samples
234 --------------------------------------- 157 ---------------------------------------
235 b x f1 158 b x f1
236 b x x f2 159 b x x f2
237 b x f5 160 b x f5
238 x f3 161 x f3
239 x x f4 162 x x f4
240 x f6 163 x f6
241 164
242 COMPARISON METHODS 165 COMPARISON METHODS
243 ------------------ 166 ------------------
244 delta 167 delta
245 ~~~~~ 168 ~~~~~
246 If specified the 'Delta' column is displayed w 169 If specified the 'Delta' column is displayed with value 'd' computed as:
247 170
248 d = A->period_percent - B->period_percent 171 d = A->period_percent - B->period_percent
249 172
250 with: 173 with:
251 - A/B being matching hist entry from data/ba 174 - A/B being matching hist entry from data/baseline file specified
252 (or perf.data/perf.data.old) respectively. 175 (or perf.data/perf.data.old) respectively.
253 176
254 - period_percent being the % of the hist ent 177 - period_percent being the % of the hist entry period value within
255 single data file 178 single data file
256 179
257 - with filtering by -C, -d and/or -S, period 180 - with filtering by -C, -d and/or -S, period_percent might be changed
258 relative to how entries are filtered. Use 181 relative to how entries are filtered. Use --percentage=absolute to
259 prevent such fluctuation. 182 prevent such fluctuation.
260 183
261 delta-abs <<
262 ~~~~~~~~~ <<
263 Same as 'delta` method, but sort the result wi <<
264 <<
265 ratio 184 ratio
266 ~~~~~ 185 ~~~~~
267 If specified the 'Ratio' column is displayed w 186 If specified the 'Ratio' column is displayed with value 'r' computed as:
268 187
269 r = A->period / B->period 188 r = A->period / B->period
270 189
271 with: 190 with:
272 - A/B being matching hist entry from data/ba 191 - A/B being matching hist entry from data/baseline file specified
273 (or perf.data/perf.data.old) respectively. 192 (or perf.data/perf.data.old) respectively.
274 193
275 - period being the hist entry period value 194 - period being the hist entry period value
276 195
277 wdiff:WEIGHT-B,WEIGHT-A 196 wdiff:WEIGHT-B,WEIGHT-A
278 ~~~~~~~~~~~~~~~~~~~~~~~ 197 ~~~~~~~~~~~~~~~~~~~~~~~
279 If specified the 'Weighted diff' column is dis 198 If specified the 'Weighted diff' column is displayed with value 'd' computed as:
280 199
281 d = B->period * WEIGHT-A - A->period * WEIG 200 d = B->period * WEIGHT-A - A->period * WEIGHT-B
282 201
283 - A/B being matching hist entry from data/ba 202 - A/B being matching hist entry from data/baseline file specified
284 (or perf.data/perf.data.old) respectively. 203 (or perf.data/perf.data.old) respectively.
285 204
286 - period being the hist entry period value 205 - period being the hist entry period value
287 206
288 - WEIGHT-A/WEIGHT-B being user supplied weig 207 - WEIGHT-A/WEIGHT-B being user supplied weights in the the '-c' option
289 behind ':' separator like '-c wdiff:1,2'. 208 behind ':' separator like '-c wdiff:1,2'.
290 - WEIGHT-A being the weight of the data fi 209 - WEIGHT-A being the weight of the data file
291 - WEIGHT-B being the weight of the baselin 210 - WEIGHT-B being the weight of the baseline data file
292 <<
293 cycles <<
294 ~~~~~~ <<
295 If specified the '[Program Block Range] Cycles <<
296 It displays the cycles difference of same prog <<
297 two perf.data. The program basic block is the <<
298 <<
299 '[Program Block Range]' indicates the range of <<
300 Source line is reported if it can be found oth <<
301 instead. <<
302 211
303 SEE ALSO 212 SEE ALSO
304 -------- 213 --------
305 linkperf:perf-record[1], linkperf:perf-report[ 214 linkperf:perf-record[1], linkperf:perf-report[1]
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