1 perf-script-perl(1) 1 perf-script-perl(1)
2 =================== 2 ===================
3 3
4 NAME 4 NAME
5 ---- 5 ----
6 perf-script-perl - Process trace data with a P 6 perf-script-perl - Process trace data with a Perl script
7 7
8 SYNOPSIS 8 SYNOPSIS
9 -------- 9 --------
10 [verse] 10 [verse]
11 'perf script' [-s [Perl]:script[.pl] ] 11 'perf script' [-s [Perl]:script[.pl] ]
12 12
13 DESCRIPTION 13 DESCRIPTION
14 ----------- 14 -----------
15 15
16 This perf script option is used to process per 16 This perf script option is used to process perf script data using perf's
17 built-in Perl interpreter. It reads and proce 17 built-in Perl interpreter. It reads and processes the input file and
18 displays the results of the trace analysis imp 18 displays the results of the trace analysis implemented in the given
19 Perl script, if any. 19 Perl script, if any.
20 20
21 STARTER SCRIPTS 21 STARTER SCRIPTS
22 --------------- 22 ---------------
23 23
24 You can avoid reading the rest of this documen 24 You can avoid reading the rest of this document by running 'perf script
25 -g perl' in the same directory as an existing 25 -g perl' in the same directory as an existing perf.data trace file.
26 That will generate a starter script containing 26 That will generate a starter script containing a handler for each of
27 the event types in the trace file; it simply p 27 the event types in the trace file; it simply prints every available
28 field for each event in the trace file. 28 field for each event in the trace file.
29 29
30 You can also look at the existing scripts in 30 You can also look at the existing scripts in
31 ~/libexec/perf-core/scripts/perl for typical e 31 ~/libexec/perf-core/scripts/perl for typical examples showing how to
32 do basic things like aggregate event data, pri 32 do basic things like aggregate event data, print results, etc. Also,
33 the check-perf-script.pl script, while not int 33 the check-perf-script.pl script, while not interesting for its results,
34 attempts to exercise all of the main scripting 34 attempts to exercise all of the main scripting features.
35 35
36 EVENT HANDLERS 36 EVENT HANDLERS
37 -------------- 37 --------------
38 38
39 When perf script is invoked using a trace scri 39 When perf script is invoked using a trace script, a user-defined
40 'handler function' is called for each event in 40 'handler function' is called for each event in the trace. If there's
41 no handler function defined for a given event 41 no handler function defined for a given event type, the event is
42 ignored (or passed to a 'trace_unhandled' func 42 ignored (or passed to a 'trace_unhandled' function, see below) and the
43 next event is processed. 43 next event is processed.
44 44
45 Most of the event's field values are passed as 45 Most of the event's field values are passed as arguments to the
46 handler function; some of the less common ones 46 handler function; some of the less common ones aren't - those are
47 available as calls back into the perf executab 47 available as calls back into the perf executable (see below).
48 48
49 As an example, the following perf record comma 49 As an example, the following perf record command can be used to record
50 all sched_wakeup events in the system: 50 all sched_wakeup events in the system:
51 51
52 # perf record -a -e sched:sched_wakeup 52 # perf record -a -e sched:sched_wakeup
53 53
54 Traces meant to be processed using a script sh 54 Traces meant to be processed using a script should be recorded with
55 the above option: -a to enable system-wide col 55 the above option: -a to enable system-wide collection.
56 56
57 The format file for the sched_wakeup event def 57 The format file for the sched_wakeup event defines the following fields
58 (see /sys/kernel/tracing/events/sched/sched_wa 58 (see /sys/kernel/tracing/events/sched/sched_wakeup/format):
59 59
60 ---- 60 ----
61 format: 61 format:
62 field:unsigned short common_type; 62 field:unsigned short common_type;
63 field:unsigned char common_flags; 63 field:unsigned char common_flags;
64 field:unsigned char common_preempt_cou 64 field:unsigned char common_preempt_count;
65 field:int common_pid; 65 field:int common_pid;
66 66
67 field:char comm[TASK_COMM_LEN]; 67 field:char comm[TASK_COMM_LEN];
68 field:pid_t pid; 68 field:pid_t pid;
69 field:int prio; 69 field:int prio;
70 field:int success; 70 field:int success;
71 field:int target_cpu; 71 field:int target_cpu;
72 ---- 72 ----
73 73
74 The handler function for this event would be d 74 The handler function for this event would be defined as:
75 75
76 ---- 76 ----
77 sub sched::sched_wakeup 77 sub sched::sched_wakeup
78 { 78 {
79 my ($event_name, $context, $common_cpu, $co 79 my ($event_name, $context, $common_cpu, $common_secs,
80 $common_nsecs, $common_pid, $common_com 80 $common_nsecs, $common_pid, $common_comm,
81 $comm, $pid, $prio, $success, $target_c 81 $comm, $pid, $prio, $success, $target_cpu) = @_;
82 } 82 }
83 ---- 83 ----
84 84
85 The handler function takes the form subsystem: 85 The handler function takes the form subsystem::event_name.
86 86
87 The $common_* arguments in the handler's argum 87 The $common_* arguments in the handler's argument list are the set of
88 arguments passed to all event handlers; some o 88 arguments passed to all event handlers; some of the fields correspond
89 to the common_* fields in the format file, but 89 to the common_* fields in the format file, but some are synthesized,
90 and some of the common_* fields aren't common 90 and some of the common_* fields aren't common enough to to be passed
91 to every event as arguments but are available 91 to every event as arguments but are available as library functions.
92 92
93 Here's a brief description of each of the inva 93 Here's a brief description of each of the invariant event args:
94 94
95 $event_name the name of the ev 95 $event_name the name of the event as text
96 $context an opaque 'cookie' 96 $context an opaque 'cookie' used in calls back into perf
97 $common_cpu the cpu the event 97 $common_cpu the cpu the event occurred on
98 $common_secs the secs portion o 98 $common_secs the secs portion of the event timestamp
99 $common_nsecs the nsecs portion 99 $common_nsecs the nsecs portion of the event timestamp
100 $common_pid the pid of the cur 100 $common_pid the pid of the current task
101 $common_comm the name of the cu 101 $common_comm the name of the current process
102 102
103 All of the remaining fields in the event's for 103 All of the remaining fields in the event's format file have
104 counterparts as handler function arguments of 104 counterparts as handler function arguments of the same name, as can be
105 seen in the example above. 105 seen in the example above.
106 106
107 The above provides the basics needed to direct 107 The above provides the basics needed to directly access every field of
108 every event in a trace, which covers 90% of wh 108 every event in a trace, which covers 90% of what you need to know to
109 write a useful trace script. The sections bel 109 write a useful trace script. The sections below cover the rest.
110 110
111 SCRIPT LAYOUT 111 SCRIPT LAYOUT
112 ------------- 112 -------------
113 113
114 Every perf script Perl script should start by 114 Every perf script Perl script should start by setting up a Perl module
115 search path and 'use'ing a few support modules 115 search path and 'use'ing a few support modules (see module
116 descriptions below): 116 descriptions below):
117 117
118 ---- 118 ----
119 use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/ 119 use lib "$ENV{'PERF_EXEC_PATH'}/scripts/perl/Perf-Trace-Util/lib";
120 use lib "./Perf-Trace-Util/lib"; 120 use lib "./Perf-Trace-Util/lib";
121 use Perf::Trace::Core; 121 use Perf::Trace::Core;
122 use Perf::Trace::Context; 122 use Perf::Trace::Context;
123 use Perf::Trace::Util; 123 use Perf::Trace::Util;
124 ---- 124 ----
125 125
126 The rest of the script can contain handler fun 126 The rest of the script can contain handler functions and support
127 functions in any order. 127 functions in any order.
128 128
129 Aside from the event handler functions discuss 129 Aside from the event handler functions discussed above, every script
130 can implement a set of optional functions: 130 can implement a set of optional functions:
131 131
132 *trace_begin*, if defined, is called before an 132 *trace_begin*, if defined, is called before any event is processed and
133 gives scripts a chance to do setup tasks: 133 gives scripts a chance to do setup tasks:
134 134
135 ---- 135 ----
136 sub trace_begin 136 sub trace_begin
137 { 137 {
138 } 138 }
139 ---- 139 ----
140 140
141 *trace_end*, if defined, is called after all e 141 *trace_end*, if defined, is called after all events have been
142 processed and gives scripts a chance to do en 142 processed and gives scripts a chance to do end-of-script tasks, such
143 as display results: 143 as display results:
144 144
145 ---- 145 ----
146 sub trace_end 146 sub trace_end
147 { 147 {
148 } 148 }
149 ---- 149 ----
150 150
151 *trace_unhandled*, if defined, is called after 151 *trace_unhandled*, if defined, is called after for any event that
152 doesn't have a handler explicitly defined for 152 doesn't have a handler explicitly defined for it. The standard set
153 of common arguments are passed into it: 153 of common arguments are passed into it:
154 154
155 ---- 155 ----
156 sub trace_unhandled 156 sub trace_unhandled
157 { 157 {
158 my ($event_name, $context, $common_cpu, $c 158 my ($event_name, $context, $common_cpu, $common_secs,
159 $common_nsecs, $common_pid, $common_co 159 $common_nsecs, $common_pid, $common_comm) = @_;
160 } 160 }
161 ---- 161 ----
162 162
163 The remaining sections provide descriptions of 163 The remaining sections provide descriptions of each of the available
164 built-in perf script Perl modules and their as 164 built-in perf script Perl modules and their associated functions.
165 165
166 AVAILABLE MODULES AND FUNCTIONS 166 AVAILABLE MODULES AND FUNCTIONS
167 ------------------------------- 167 -------------------------------
168 168
169 The following sections describe the functions 169 The following sections describe the functions and variables available
170 via the various Perf::Trace::* Perl modules. 170 via the various Perf::Trace::* Perl modules. To use the functions and
171 variables from the given module, add the corre 171 variables from the given module, add the corresponding 'use
172 Perf::Trace::XXX' line to your perf script scr 172 Perf::Trace::XXX' line to your perf script script.
173 173
174 Perf::Trace::Core Module 174 Perf::Trace::Core Module
175 ~~~~~~~~~~~~~~~~~~~~~~~~ 175 ~~~~~~~~~~~~~~~~~~~~~~~~
176 176
177 These functions provide some essential functio 177 These functions provide some essential functions to user scripts.
178 178
179 The *flag_str* and *symbol_str* functions prov 179 The *flag_str* and *symbol_str* functions provide human-readable
180 strings for flag and symbolic fields. These c 180 strings for flag and symbolic fields. These correspond to the strings
181 and values parsed from the 'print fmt' fields 181 and values parsed from the 'print fmt' fields of the event format
182 files: 182 files:
183 183
184 flag_str($event_name, $field_name, $field_va 184 flag_str($event_name, $field_name, $field_value) - returns the string representation corresponding to $field_value for the flag field $field_name of event $event_name
185 symbol_str($event_name, $field_name, $field_ 185 symbol_str($event_name, $field_name, $field_value) - returns the string representation corresponding to $field_value for the symbolic field $field_name of event $event_name
186 186
187 Perf::Trace::Context Module 187 Perf::Trace::Context Module
188 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 188 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
189 189
190 Some of the 'common' fields in the event forma 190 Some of the 'common' fields in the event format file aren't all that
191 common, but need to be made accessible to user 191 common, but need to be made accessible to user scripts nonetheless.
192 192
193 Perf::Trace::Context defines a set of function 193 Perf::Trace::Context defines a set of functions that can be used to
194 access this data in the context of the current 194 access this data in the context of the current event. Each of these
195 functions expects a $context variable, which i 195 functions expects a $context variable, which is the same as the
196 $context variable passed into every event hand 196 $context variable passed into every event handler as the second
197 argument. 197 argument.
198 198
199 common_pc($context) - returns common_preempt 199 common_pc($context) - returns common_preempt count for the current event
200 common_flags($context) - returns common_flags 200 common_flags($context) - returns common_flags for the current event
201 common_lock_depth($context) - returns common_ 201 common_lock_depth($context) - returns common_lock_depth for the current event
202 202
203 Perf::Trace::Util Module 203 Perf::Trace::Util Module
204 ~~~~~~~~~~~~~~~~~~~~~~~~ 204 ~~~~~~~~~~~~~~~~~~~~~~~~
205 205
206 Various utility functions for use with perf sc 206 Various utility functions for use with perf script:
207 207
208 nsecs($secs, $nsecs) - returns total nsecs g 208 nsecs($secs, $nsecs) - returns total nsecs given secs/nsecs pair
209 nsecs_secs($nsecs) - returns whole secs port 209 nsecs_secs($nsecs) - returns whole secs portion given nsecs
210 nsecs_nsecs($nsecs) - returns nsecs remainde 210 nsecs_nsecs($nsecs) - returns nsecs remainder given nsecs
211 nsecs_str($nsecs) - returns printable string 211 nsecs_str($nsecs) - returns printable string in the form secs.nsecs
212 avg($total, $n) - returns average given a su 212 avg($total, $n) - returns average given a sum and a total number of values
213 213
214 SEE ALSO 214 SEE ALSO
215 -------- 215 --------
216 linkperf:perf-script[1] 216 linkperf:perf-script[1]
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