1 perf-diff(1) 2 ============ 3 4 NAME 5 ---- 6 perf-diff - Read perf.data files and display the differential profile 7 8 SYNOPSIS 9 -------- 10 [verse] 11 'perf diff' [baseline file] [data file1] [[data file2] ... ] 12 13 DESCRIPTION 14 ----------- 15 This command displays the performance difference amongst two or more perf.data 16 files captured via perf record. 17 18 If no parameters are passed it will assume perf.data.old and perf.data. 19 20 The differential profile is displayed only for events matching both 21 specified perf.data files. 22 23 OPTIONS 24 ------- 25 -D:: 26 --dump-raw-trace:: 27 Dump raw trace in ASCII. 28 29 -m:: 30 --modules:: 31 Load module symbols. WARNING: use only with -k and LIVE kernel 32 33 -d:: 34 --dsos=:: 35 Only consider symbols in these dsos. CSV that understands 36 file://filename entries. 37 38 -C:: 39 --comms=:: 40 Only consider symbols in these comms. CSV that understands 41 file://filename entries. 42 43 -S:: 44 --symbols=:: 45 Only consider these symbols. CSV that understands 46 file://filename entries. 47 48 -s:: 49 --sort=:: 50 Sort by key(s): pid, comm, dso, symbol. 51 52 -t:: 53 --field-separator=:: 54 55 Use a special separator character and don't pad with spaces, replacing 56 all occurrences of this separator in symbol names (and other output) 57 with a '.' character, that thus it's the only non valid separator. 58 59 -v:: 60 --verbose:: 61 Be verbose, for instance, show the raw counts in addition to the 62 diff. 63 64 -f:: 65 --force:: 66 Don't complain, do it. 67 68 --symfs=<directory>:: 69 Look for files with symbols relative to this directory. 70 71 -b:: 72 --baseline-only:: 73 Show only items with match in baseline. 74 75 -c:: 76 --compute:: 77 Differential computation selection - delta,ratio,wdiff (default is delta). 78 See COMPARISON METHODS section for more info. 79 80 -p:: 81 --period:: 82 Show period values for both compared hist entries. 83 84 -F:: 85 --formula:: 86 Show formula for given computation. 87 88 -o:: 89 --order:: 90 Specify compute sorting column number. 91 92 COMPARISON 93 ---------- 94 The comparison is governed by the baseline file. The baseline perf.data 95 file is iterated for samples. All other perf.data files specified on 96 the command line are searched for the baseline sample pair. If the pair 97 is found, specified computation is made and result is displayed. 98 99 All samples from non-baseline perf.data files, that do not match any 100 baseline entry, are displayed with empty space within baseline column 101 and possible computation results (delta) in their related column. 102 103 Example files samples: 104 - file A with samples f1, f2, f3, f4, f6 105 - file B with samples f2, f4, f5 106 - file C with samples f1, f2, f5 107 108 Example output: 109 x - computation takes place for pair 110 b - baseline sample percentage 111 112 - perf diff A B C 113 114 baseline/A compute/B compute/C samples 115 --------------------------------------- 116 b x f1 117 b x x f2 118 b f3 119 b x f4 120 b f6 121 x x f5 122 123 - perf diff B A C 124 125 baseline/B compute/A compute/C samples 126 --------------------------------------- 127 b x x f2 128 b x f4 129 b x f5 130 x x f1 131 x f3 132 x f6 133 134 - perf diff C B A 135 136 baseline/C compute/B compute/A samples 137 --------------------------------------- 138 b x f1 139 b x x f2 140 b x f5 141 x f3 142 x x f4 143 x f6 144 145 COMPARISON METHODS 146 ------------------ 147 delta 148 ~~~~~ 149 If specified the 'Delta' column is displayed with value 'd' computed as: 150 151 d = A->period_percent - B->period_percent 152 153 with: 154 - A/B being matching hist entry from data/baseline file specified 155 (or perf.data/perf.data.old) respectively. 156 157 - period_percent being the % of the hist entry period value within 158 single data file 159 160 ratio 161 ~~~~~ 162 If specified the 'Ratio' column is displayed with value 'r' computed as: 163 164 r = A->period / B->period 165 166 with: 167 - A/B being matching hist entry from data/baseline file specified 168 (or perf.data/perf.data.old) respectively. 169 170 - period being the hist entry period value 171 172 wdiff:WEIGHT-B,WEIGHT-A 173 ~~~~~~~~~~~~~~~~~~~~~~~ 174 If specified the 'Weighted diff' column is displayed with value 'd' computed as: 175 176 d = B->period * WEIGHT-A - A->period * WEIGHT-B 177 178 - A/B being matching hist entry from data/baseline file specified 179 (or perf.data/perf.data.old) respectively. 180 181 - period being the hist entry period value 182 183 - WEIGHT-A/WEIGHT-B being user suplied weights in the the '-c' option 184 behind ':' separator like '-c wdiff:1,2'. 185 - WIEGHT-A being the weight of the data file 186 - WIEGHT-B being the weight of the baseline data file 187 188 SEE ALSO 189 -------- 190 linkperf:perf-record[1] 191
