1perf-diff(1)
2============
3
4NAME
5----
6perf-diff - Read perf.data files and display the differential profile
7
8SYNOPSIS
9--------
10[verse]
11'perf diff' [baseline file] [data file1] [[data file2] ... ]
12
13DESCRIPTION
14-----------
15This command displays the performance difference amongst two or more perf.data
16files captured via perf record.
17
18If no parameters are passed it will assume perf.data.old and perf.data.
19
20The differential profile is displayed only for events matching both
21specified perf.data files.
22
23OPTIONS
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
92COMPARISON
93----------
94The comparison is governed by the baseline file. The baseline perf.data
95file is iterated for samples. All other perf.data files specified on
96the command line are searched for the baseline sample pair. If the pair
97is found, specified computation is made and result is displayed.
98
99All samples from non-baseline perf.data files, that do not match any
100baseline entry, are displayed with empty space within baseline column
101and possible computation results (delta) in their related column.
102
103Example 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
108Example 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
145COMPARISON METHODS
146------------------
147delta
148~~~~~
149If specified the 'Delta' column is displayed with value 'd' computed as:
150
151  d = A->period_percent - B->period_percent
152
153with:
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
160ratio
161~~~~~
162If specified the 'Ratio' column is displayed with value 'r' computed as:
163
164  r = A->period / B->period
165
166with:
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
172wdiff:WEIGHT-B,WEIGHT-A
173~~~~~~~~~~~~~~~~~~~~~~~
174If 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
188SEE ALSO
189--------
190linkperf:perf-record[1]
191