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