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:: 76 -q::
77 --quiet:: 77 --quiet::
78 Do not show any warnings or messages. !! 78 Do not show any message. (Suppress -v)
79 79
80 -f:: 80 -f::
81 --force:: 81 --force::
82 Don't do ownership validation. 82 Don't do ownership validation.
83 83
84 --symfs=<directory>:: 84 --symfs=<directory>::
85 Look for files with symbols relative t 85 Look for files with symbols relative to this directory.
86 86
87 -b:: 87 -b::
88 --baseline-only:: 88 --baseline-only::
89 Show only items with match in baseline 89 Show only items with match in baseline.
90 90
91 -c:: 91 -c::
92 --compute:: 92 --compute::
93 Differential computation selection - d 93 Differential computation selection - delta, ratio, wdiff, cycles,
94 delta-abs (default is delta-abs). Def 94 delta-abs (default is delta-abs). Default can be changed using
95 diff.compute config option. See COMPA 95 diff.compute config option. See COMPARISON METHODS section for
96 more info. 96 more info.
97 97
98 --cycles-hist:: 98 --cycles-hist::
99 Report a histogram and the standard de 99 Report a histogram and the standard deviation for cycles data.
100 It can help us to judge if the reporte 100 It can help us to judge if the reported cycles data is noisy or
101 not. This option should be used with ' 101 not. This option should be used with '-c cycles'.
102 102
103 -p:: 103 -p::
104 --period:: 104 --period::
105 Show period values for both compared h 105 Show period values for both compared hist entries.
106 106
107 -F:: 107 -F::
108 --formula:: 108 --formula::
109 Show formula for given computation. 109 Show formula for given computation.
110 110
111 -o:: 111 -o::
112 --order:: 112 --order::
113 Specify compute sorting column number. 113 Specify compute sorting column number. 0 means sorting by baseline
114 overhead and 1 (default) means sorting 114 overhead and 1 (default) means sorting by computed value of column 1
115 (data from the first file other base ba 115 (data from the first file other base baseline). Values more than 1
116 can be used only if enough data files a 116 can be used only if enough data files are provided.
117 The default value can be set using the 117 The default value can be set using the diff.order config option.
118 118
119 --percentage:: 119 --percentage::
120 Determine how to display the overhead 120 Determine how to display the overhead percentage of filtered entries.
121 Filters can be applied by --comms, --d 121 Filters can be applied by --comms, --dsos and/or --symbols options.
122 122
123 "relative" means it's relative to filt 123 "relative" means it's relative to filtered entries only so that the
124 sum of shown entries will be always 10 124 sum of shown entries will be always 100%. "absolute" means it retains
125 the original value before and after th 125 the original value before and after the filter is applied.
126 126
127 --time:: 127 --time::
128 Analyze samples within given time wind 128 Analyze samples within given time window. It supports time
129 percent with multiple time ranges. Tim 129 percent with multiple time ranges. Time string is 'a%/n,b%/m,...'
130 or 'a%-b%,c%-%d,...'. 130 or 'a%-b%,c%-%d,...'.
131 131
132 For example: 132 For example:
133 133
134 Select the second 10% time slice to di 134 Select the second 10% time slice to diff:
135 135
136 perf diff --time 10%/2 136 perf diff --time 10%/2
137 137
138 Select from 0% to 10% time slice to di 138 Select from 0% to 10% time slice to diff:
139 139
140 perf diff --time 0%-10% 140 perf diff --time 0%-10%
141 141
142 Select the first and the second 10% ti 142 Select the first and the second 10% time slices to diff:
143 143
144 perf diff --time 10%/1,10%/2 144 perf diff --time 10%/1,10%/2
145 145
146 Select from 0% to 10% and 30% to 40% s 146 Select from 0% to 10% and 30% to 40% slices to diff:
147 147
148 perf diff --time 0%-10%,30%-40% 148 perf diff --time 0%-10%,30%-40%
149 149
150 It also supports analyzing samples wit 150 It also supports analyzing samples within a given time window
151 <start>,<stop>. Times have the format 151 <start>,<stop>. Times have the format seconds.nanoseconds. If 'start'
152 is not given (i.e. time string is ',x. 152 is not given (i.e. time string is ',x.y') then analysis starts at
153 the beginning of the file. If stop tim 153 the beginning of the file. If stop time is not given (i.e. time
154 string is 'x.y,') then analysis goes t 154 string is 'x.y,') then analysis goes to the end of the file.
155 Multiple ranges can be separated by sp 155 Multiple ranges can be separated by spaces, which requires the argument
156 to be quoted e.g. --time "1234.567,123 156 to be quoted e.g. --time "1234.567,1234.789 1235,"
157 Time string is'a1.b1,c1.d1:a2.b2,c2.d2 157 Time string is'a1.b1,c1.d1:a2.b2,c2.d2'. Use ':' to separate timestamps
158 for different perf.data files. 158 for different perf.data files.
159 159
160 For example, we get the timestamp info 160 For example, we get the timestamp information from 'perf script'.
161 161
162 perf script -i perf.data.old 162 perf script -i perf.data.old
163 mgen 13940 [000] 3946.361400: ... 163 mgen 13940 [000] 3946.361400: ...
164 164
165 perf script -i perf.data 165 perf script -i perf.data
166 mgen 13940 [000] 3971.150589 ... 166 mgen 13940 [000] 3971.150589 ...
167 167
168 perf diff --time 3946.361400,:3971.1 168 perf diff --time 3946.361400,:3971.150589,
169 169
170 It analyzes the perf.data.old from the 170 It analyzes the perf.data.old from the timestamp 3946.361400 to
171 the end of perf.data.old and analyzes 171 the end of perf.data.old and analyzes the perf.data from the
172 timestamp 3971.150589 to the end of pe 172 timestamp 3971.150589 to the end of perf.data.
173 173
174 --cpu:: Only diff samples for the list of CPUs 174 --cpu:: Only diff samples for the list of CPUs provided. Multiple CPUs can
175 be provided as a comma-separated list 175 be provided as a comma-separated list with no space: 0,1. Ranges of
176 CPUs are specified with -: 0-2. Defaul 176 CPUs are specified with -: 0-2. Default is to report samples on all
177 CPUs. 177 CPUs.
178 178
179 --pid=:: 179 --pid=::
180 Only diff samples for given process ID 180 Only diff samples for given process ID (comma separated list).
181 181
182 --tid=:: 182 --tid=::
183 Only diff samples for given thread ID 183 Only diff samples for given thread ID (comma separated list).
184 <<
185 --stream:: <<
186 Enable hot streams comparison. Stream <<
187 aggregated by the branch records from <<
188 184
189 COMPARISON 185 COMPARISON
190 ---------- 186 ----------
191 The comparison is governed by the baseline fil 187 The comparison is governed by the baseline file. The baseline perf.data
192 file is iterated for samples. All other perf.d 188 file is iterated for samples. All other perf.data files specified on
193 the command line are searched for the baseline 189 the command line are searched for the baseline sample pair. If the pair
194 is found, specified computation is made and re 190 is found, specified computation is made and result is displayed.
195 191
196 All samples from non-baseline perf.data files, 192 All samples from non-baseline perf.data files, that do not match any
197 baseline entry, are displayed with empty space 193 baseline entry, are displayed with empty space within baseline column
198 and possible computation results (delta) in th 194 and possible computation results (delta) in their related column.
199 195
200 Example files samples: 196 Example files samples:
201 - file A with samples f1, f2, f3, f4, f6 197 - file A with samples f1, f2, f3, f4, f6
202 - file B with samples f2, f4, f5 198 - file B with samples f2, f4, f5
203 - file C with samples f1, f2, f5 199 - file C with samples f1, f2, f5
204 200
205 Example output: 201 Example output:
206 x - computation takes place for pair 202 x - computation takes place for pair
207 b - baseline sample percentage 203 b - baseline sample percentage
208 204
209 - perf diff A B C 205 - perf diff A B C
210 206
211 baseline/A compute/B compute/C samples 207 baseline/A compute/B compute/C samples
212 --------------------------------------- 208 ---------------------------------------
213 b x f1 209 b x f1
214 b x x f2 210 b x x f2
215 b f3 211 b f3
216 b x f4 212 b x f4
217 b f6 213 b f6
218 x x f5 214 x x f5
219 215
220 - perf diff B A C 216 - perf diff B A C
221 217
222 baseline/B compute/A compute/C samples 218 baseline/B compute/A compute/C samples
223 --------------------------------------- 219 ---------------------------------------
224 b x x f2 220 b x x f2
225 b x f4 221 b x f4
226 b x f5 222 b x f5
227 x x f1 223 x x f1
228 x f3 224 x f3
229 x f6 225 x f6
230 226
231 - perf diff C B A 227 - perf diff C B A
232 228
233 baseline/C compute/B compute/A samples 229 baseline/C compute/B compute/A samples
234 --------------------------------------- 230 ---------------------------------------
235 b x f1 231 b x f1
236 b x x f2 232 b x x f2
237 b x f5 233 b x f5
238 x f3 234 x f3
239 x x f4 235 x x f4
240 x f6 236 x f6
241 237
242 COMPARISON METHODS 238 COMPARISON METHODS
243 ------------------ 239 ------------------
244 delta 240 delta
245 ~~~~~ 241 ~~~~~
246 If specified the 'Delta' column is displayed w 242 If specified the 'Delta' column is displayed with value 'd' computed as:
247 243
248 d = A->period_percent - B->period_percent 244 d = A->period_percent - B->period_percent
249 245
250 with: 246 with:
251 - A/B being matching hist entry from data/ba 247 - A/B being matching hist entry from data/baseline file specified
252 (or perf.data/perf.data.old) respectively. 248 (or perf.data/perf.data.old) respectively.
253 249
254 - period_percent being the % of the hist ent 250 - period_percent being the % of the hist entry period value within
255 single data file 251 single data file
256 252
257 - with filtering by -C, -d and/or -S, period 253 - with filtering by -C, -d and/or -S, period_percent might be changed
258 relative to how entries are filtered. Use 254 relative to how entries are filtered. Use --percentage=absolute to
259 prevent such fluctuation. 255 prevent such fluctuation.
260 256
261 delta-abs 257 delta-abs
262 ~~~~~~~~~ 258 ~~~~~~~~~
263 Same as 'delta` method, but sort the result wi 259 Same as 'delta` method, but sort the result with the absolute values.
264 260
265 ratio 261 ratio
266 ~~~~~ 262 ~~~~~
267 If specified the 'Ratio' column is displayed w 263 If specified the 'Ratio' column is displayed with value 'r' computed as:
268 264
269 r = A->period / B->period 265 r = A->period / B->period
270 266
271 with: 267 with:
272 - A/B being matching hist entry from data/ba 268 - A/B being matching hist entry from data/baseline file specified
273 (or perf.data/perf.data.old) respectively. 269 (or perf.data/perf.data.old) respectively.
274 270
275 - period being the hist entry period value 271 - period being the hist entry period value
276 272
277 wdiff:WEIGHT-B,WEIGHT-A 273 wdiff:WEIGHT-B,WEIGHT-A
278 ~~~~~~~~~~~~~~~~~~~~~~~ 274 ~~~~~~~~~~~~~~~~~~~~~~~
279 If specified the 'Weighted diff' column is dis 275 If specified the 'Weighted diff' column is displayed with value 'd' computed as:
280 276
281 d = B->period * WEIGHT-A - A->period * WEIG 277 d = B->period * WEIGHT-A - A->period * WEIGHT-B
282 278
283 - A/B being matching hist entry from data/ba 279 - A/B being matching hist entry from data/baseline file specified
284 (or perf.data/perf.data.old) respectively. 280 (or perf.data/perf.data.old) respectively.
285 281
286 - period being the hist entry period value 282 - period being the hist entry period value
287 283
288 - WEIGHT-A/WEIGHT-B being user supplied weig 284 - WEIGHT-A/WEIGHT-B being user supplied weights in the the '-c' option
289 behind ':' separator like '-c wdiff:1,2'. 285 behind ':' separator like '-c wdiff:1,2'.
290 - WEIGHT-A being the weight of the data fi 286 - WEIGHT-A being the weight of the data file
291 - WEIGHT-B being the weight of the baselin 287 - WEIGHT-B being the weight of the baseline data file
292 288
293 cycles 289 cycles
294 ~~~~~~ 290 ~~~~~~
295 If specified the '[Program Block Range] Cycles 291 If specified the '[Program Block Range] Cycles Diff' column is displayed.
296 It displays the cycles difference of same prog 292 It displays the cycles difference of same program basic block amongst
297 two perf.data. The program basic block is the 293 two perf.data. The program basic block is the code between two branches.
298 294
299 '[Program Block Range]' indicates the range of 295 '[Program Block Range]' indicates the range of a program basic block.
300 Source line is reported if it can be found oth 296 Source line is reported if it can be found otherwise uses symbol+offset
301 instead. 297 instead.
302 298
303 SEE ALSO 299 SEE ALSO
304 -------- 300 --------
305 linkperf:perf-record[1], linkperf:perf-report[ 301 linkperf:perf-record[1], linkperf:perf-report[1]
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