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Ingo Molnar133dc4c2010-11-16 18:45:39 +01001perf-script-python(1)
Arnaldo Carvalho de Melo4778e0e2010-05-05 11:23:27 -03002====================
Tom Zanussicff68e52010-01-27 02:28:03 -06003
4NAME
5----
Ingo Molnar133dc4c2010-11-16 18:45:39 +01006perf-script-python - Process trace data with a Python script
Tom Zanussicff68e52010-01-27 02:28:03 -06007
8SYNOPSIS
9--------
10[verse]
Ingo Molnar133dc4c2010-11-16 18:45:39 +010011'perf script' [-s [Python]:script[.py] ]
Tom Zanussicff68e52010-01-27 02:28:03 -060012
13DESCRIPTION
14-----------
15
Ingo Molnar133dc4c2010-11-16 18:45:39 +010016This perf script option is used to process perf script data using perf's
Tom Zanussicff68e52010-01-27 02:28:03 -060017built-in Python interpreter. It reads and processes the input file and
18displays the results of the trace analysis implemented in the given
19Python script, if any.
20
21A QUICK EXAMPLE
22---------------
23
24This section shows the process, start to finish, of creating a working
25Python script that aggregates and extracts useful information from a
Ingo Molnar133dc4c2010-11-16 18:45:39 +010026raw perf script stream. You can avoid reading the rest of this
Tom Zanussicff68e52010-01-27 02:28:03 -060027document if an example is enough for you; the rest of the document
28provides more details on each step and lists the library functions
29available to script writers.
30
31This example actually details the steps that were used to create the
Ingo Molnar133dc4c2010-11-16 18:45:39 +010032'syscall-counts' script you see when you list the available perf script
33scripts via 'perf script -l'. As such, this script also shows how to
34integrate your script into the list of general-purpose 'perf script'
Tom Zanussicff68e52010-01-27 02:28:03 -060035scripts listed by that command.
36
37The syscall-counts script is a simple script, but demonstrates all the
38basic ideas necessary to create a useful script. Here's an example
Frederic Weisbeckerc2fbaa42010-02-25 03:03:52 +010039of its output (syscall names are not yet supported, they will appear
40as numbers):
Tom Zanussicff68e52010-01-27 02:28:03 -060041
42----
43syscall events:
44
45event count
46---------------------------------------- -----------
47sys_write 455067
48sys_getdents 4072
49sys_close 3037
50sys_swapoff 1769
51sys_read 923
52sys_sched_setparam 826
53sys_open 331
54sys_newfstat 326
55sys_mmap 217
56sys_munmap 216
57sys_futex 141
58sys_select 102
59sys_poll 84
60sys_setitimer 12
61sys_writev 8
6215 8
63sys_lseek 7
64sys_rt_sigprocmask 6
65sys_wait4 3
66sys_ioctl 3
67sys_set_robust_list 1
68sys_exit 1
6956 1
70sys_access 1
71----
72
73Basically our task is to keep a per-syscall tally that gets updated
74every time a system call occurs in the system. Our script will do
75that, but first we need to record the data that will be processed by
76that script. Theoretically, there are a couple of ways we could do
77that:
78
79- we could enable every event under the tracing/events/syscalls
80 directory, but this is over 600 syscalls, well beyond the number
81 allowable by perf. These individual syscall events will however be
82 useful if we want to later use the guidance we get from the
83 general-purpose scripts to drill down and get more detail about
84 individual syscalls of interest.
85
86- we can enable the sys_enter and/or sys_exit syscalls found under
87 tracing/events/raw_syscalls. These are called for all syscalls; the
88 'id' field can be used to distinguish between individual syscall
89 numbers.
90
91For this script, we only need to know that a syscall was entered; we
92don't care how it exited, so we'll use 'perf record' to record only
93the sys_enter events:
94
95----
Frederic Weisbeckere5a5f1f2010-04-30 19:55:00 +020096# perf record -a -e raw_syscalls:sys_enter
Tom Zanussicff68e52010-01-27 02:28:03 -060097
98^C[ perf record: Woken up 1 times to write data ]
99[ perf record: Captured and wrote 56.545 MB perf.data (~2470503 samples) ]
100----
101
102The options basically say to collect data for every syscall event
103system-wide and multiplex the per-cpu output into a single stream.
104That single stream will be recorded in a file in the current directory
105called perf.data.
106
107Once we have a perf.data file containing our data, we can use the -g
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100108'perf script' option to generate a Python script that will contain a
Tom Zanussicff68e52010-01-27 02:28:03 -0600109callback handler for each event type found in the perf.data trace
110stream (for more details, see the STARTER SCRIPTS section).
111
112----
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100113# perf script -g python
114generated Python script: perf-script.py
Tom Zanussicff68e52010-01-27 02:28:03 -0600115
116The output file created also in the current directory is named
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100117perf-script.py. Here's the file in its entirety:
Tom Zanussicff68e52010-01-27 02:28:03 -0600118
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100119# perf script event handlers, generated by perf script -g python
Tom Zanussicff68e52010-01-27 02:28:03 -0600120# Licensed under the terms of the GNU GPL License version 2
121
122# The common_* event handler fields are the most useful fields common to
123# all events. They don't necessarily correspond to the 'common_*' fields
124# in the format files. Those fields not available as handler params can
125# be retrieved using Python functions of the form common_*(context).
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100126# See the perf-script-python Documentation for the list of available functions.
Tom Zanussicff68e52010-01-27 02:28:03 -0600127
128import os
129import sys
130
131sys.path.append(os.environ['PERF_EXEC_PATH'] + \
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100132 '/scripts/python/perf-script-Util/lib/Perf/Trace')
Tom Zanussicff68e52010-01-27 02:28:03 -0600133
134from perf_trace_context import *
135from Core import *
136
137def trace_begin():
138 print "in trace_begin"
139
140def trace_end():
141 print "in trace_end"
142
143def raw_syscalls__sys_enter(event_name, context, common_cpu,
144 common_secs, common_nsecs, common_pid, common_comm,
145 id, args):
146 print_header(event_name, common_cpu, common_secs, common_nsecs,
147 common_pid, common_comm)
148
149 print "id=%d, args=%s\n" % \
150 (id, args),
151
152def trace_unhandled(event_name, context, common_cpu, common_secs, common_nsecs,
153 common_pid, common_comm):
154 print_header(event_name, common_cpu, common_secs, common_nsecs,
155 common_pid, common_comm)
156
157def print_header(event_name, cpu, secs, nsecs, pid, comm):
158 print "%-20s %5u %05u.%09u %8u %-20s " % \
159 (event_name, cpu, secs, nsecs, pid, comm),
160----
161
162At the top is a comment block followed by some import statements and a
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100163path append which every perf script script should include.
Tom Zanussicff68e52010-01-27 02:28:03 -0600164
165Following that are a couple generated functions, trace_begin() and
166trace_end(), which are called at the beginning and the end of the
167script respectively (for more details, see the SCRIPT_LAYOUT section
168below).
169
170Following those are the 'event handler' functions generated one for
171every event in the 'perf record' output. The handler functions take
172the form subsystem__event_name, and contain named parameters, one for
173each field in the event; in this case, there's only one event,
174raw_syscalls__sys_enter(). (see the EVENT HANDLERS section below for
175more info on event handlers).
176
177The final couple of functions are, like the begin and end functions,
178generated for every script. The first, trace_unhandled(), is called
179every time the script finds an event in the perf.data file that
180doesn't correspond to any event handler in the script. This could
181mean either that the record step recorded event types that it wasn't
182really interested in, or the script was run against a trace file that
183doesn't correspond to the script.
184
Kirill Smelkov5d2be7c2010-05-13 14:39:25 +0400185The script generated by -g option simply prints a line for each
Tom Zanussicff68e52010-01-27 02:28:03 -0600186event found in the trace stream i.e. it basically just dumps the event
187and its parameter values to stdout. The print_header() function is
188simply a utility function used for that purpose. Let's rename the
189script and run it to see the default output:
190
191----
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100192# mv perf-script.py syscall-counts.py
193# perf script -s syscall-counts.py
Tom Zanussicff68e52010-01-27 02:28:03 -0600194
195raw_syscalls__sys_enter 1 00840.847582083 7506 perf id=1, args=
196raw_syscalls__sys_enter 1 00840.847595764 7506 perf id=1, args=
197raw_syscalls__sys_enter 1 00840.847620860 7506 perf id=1, args=
198raw_syscalls__sys_enter 1 00840.847710478 6533 npviewer.bin id=78, args=
199raw_syscalls__sys_enter 1 00840.847719204 6533 npviewer.bin id=142, args=
200raw_syscalls__sys_enter 1 00840.847755445 6533 npviewer.bin id=3, args=
201raw_syscalls__sys_enter 1 00840.847775601 6533 npviewer.bin id=3, args=
202raw_syscalls__sys_enter 1 00840.847781820 6533 npviewer.bin id=3, args=
203.
204.
205.
206----
207
208Of course, for this script, we're not interested in printing every
209trace event, but rather aggregating it in a useful way. So we'll get
210rid of everything to do with printing as well as the trace_begin() and
211trace_unhandled() functions, which we won't be using. That leaves us
212with this minimalistic skeleton:
213
214----
215import os
216import sys
217
218sys.path.append(os.environ['PERF_EXEC_PATH'] + \
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100219 '/scripts/python/perf-script-Util/lib/Perf/Trace')
Tom Zanussicff68e52010-01-27 02:28:03 -0600220
221from perf_trace_context import *
222from Core import *
223
224def trace_end():
225 print "in trace_end"
226
227def raw_syscalls__sys_enter(event_name, context, common_cpu,
228 common_secs, common_nsecs, common_pid, common_comm,
229 id, args):
230----
231
232In trace_end(), we'll simply print the results, but first we need to
233generate some results to print. To do that we need to have our
234sys_enter() handler do the necessary tallying until all events have
235been counted. A hash table indexed by syscall id is a good way to
236store that information; every time the sys_enter() handler is called,
237we simply increment a count associated with that hash entry indexed by
238that syscall id:
239
240----
241 syscalls = autodict()
242
243 try:
244 syscalls[id] += 1
245 except TypeError:
246 syscalls[id] = 1
247----
248
249The syscalls 'autodict' object is a special kind of Python dictionary
250(implemented in Core.py) that implements Perl's 'autovivifying' hashes
251in Python i.e. with autovivifying hashes, you can assign nested hash
252values without having to go to the trouble of creating intermediate
253levels if they don't exist e.g syscalls[comm][pid][id] = 1 will create
254the intermediate hash levels and finally assign the value 1 to the
255hash entry for 'id' (because the value being assigned isn't a hash
256object itself, the initial value is assigned in the TypeError
257exception. Well, there may be a better way to do this in Python but
258that's what works for now).
259
260Putting that code into the raw_syscalls__sys_enter() handler, we
261effectively end up with a single-level dictionary keyed on syscall id
262and having the counts we've tallied as values.
263
264The print_syscall_totals() function iterates over the entries in the
265dictionary and displays a line for each entry containing the syscall
266name (the dictonary keys contain the syscall ids, which are passed to
267the Util function syscall_name(), which translates the raw syscall
268numbers to the corresponding syscall name strings). The output is
269displayed after all the events in the trace have been processed, by
270calling the print_syscall_totals() function from the trace_end()
271handler called at the end of script processing.
272
273The final script producing the output shown above is shown in its
Frederic Weisbeckerc2fbaa42010-02-25 03:03:52 +0100274entirety below (syscall_name() helper is not yet available, you can
275only deal with id's for now):
Tom Zanussicff68e52010-01-27 02:28:03 -0600276
277----
278import os
279import sys
280
281sys.path.append(os.environ['PERF_EXEC_PATH'] + \
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100282 '/scripts/python/perf-script-Util/lib/Perf/Trace')
Tom Zanussicff68e52010-01-27 02:28:03 -0600283
284from perf_trace_context import *
285from Core import *
286from Util import *
287
288syscalls = autodict()
289
290def trace_end():
291 print_syscall_totals()
292
293def raw_syscalls__sys_enter(event_name, context, common_cpu,
294 common_secs, common_nsecs, common_pid, common_comm,
295 id, args):
296 try:
297 syscalls[id] += 1
298 except TypeError:
299 syscalls[id] = 1
300
301def print_syscall_totals():
302 if for_comm is not None:
303 print "\nsyscall events for %s:\n\n" % (for_comm),
304 else:
305 print "\nsyscall events:\n\n",
306
307 print "%-40s %10s\n" % ("event", "count"),
308 print "%-40s %10s\n" % ("----------------------------------------", \
309 "-----------"),
310
311 for id, val in sorted(syscalls.iteritems(), key = lambda(k, v): (v, k), \
312 reverse = True):
313 print "%-40s %10d\n" % (syscall_name(id), val),
314----
315
316The script can be run just as before:
317
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100318 # perf script -s syscall-counts.py
Tom Zanussicff68e52010-01-27 02:28:03 -0600319
320So those are the essential steps in writing and running a script. The
321process can be generalized to any tracepoint or set of tracepoints
322you're interested in - basically find the tracepoint(s) you're
323interested in by looking at the list of available events shown by
324'perf list' and/or look in /sys/kernel/debug/tracing events for
325detailed event and field info, record the corresponding trace data
326using 'perf record', passing it the list of interesting events,
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100327generate a skeleton script using 'perf script -g python' and modify the
Tom Zanussicff68e52010-01-27 02:28:03 -0600328code to aggregate and display it for your particular needs.
329
330After you've done that you may end up with a general-purpose script
331that you want to keep around and have available for future use. By
332writing a couple of very simple shell scripts and putting them in the
333right place, you can have your script listed alongside the other
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100334scripts listed by the 'perf script -l' command e.g.:
Tom Zanussicff68e52010-01-27 02:28:03 -0600335
336----
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100337root@tropicana:~# perf script -l
Tom Zanussicff68e52010-01-27 02:28:03 -0600338List of available trace scripts:
339 workqueue-stats workqueue stats (ins/exe/create/destroy)
340 wakeup-latency system-wide min/max/avg wakeup latency
341 rw-by-file <comm> r/w activity for a program, by file
342 rw-by-pid system-wide r/w activity
343----
344
345A nice side effect of doing this is that you also then capture the
346probably lengthy 'perf record' command needed to record the events for
347the script.
348
349To have the script appear as a 'built-in' script, you write two simple
350scripts, one for recording and one for 'reporting'.
351
352The 'record' script is a shell script with the same base name as your
353script, but with -record appended. The shell script should be put
354into the perf/scripts/python/bin directory in the kernel source tree.
355In that script, you write the 'perf record' command-line needed for
356your script:
357
358----
359# cat kernel-source/tools/perf/scripts/python/bin/syscall-counts-record
360
361#!/bin/bash
Frederic Weisbeckere5a5f1f2010-04-30 19:55:00 +0200362perf record -a -e raw_syscalls:sys_enter
Tom Zanussicff68e52010-01-27 02:28:03 -0600363----
364
365The 'report' script is also a shell script with the same base name as
366your script, but with -report appended. It should also be located in
367the perf/scripts/python/bin directory. In that script, you write the
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100368'perf script -s' command-line needed for running your script:
Tom Zanussicff68e52010-01-27 02:28:03 -0600369
370----
371# cat kernel-source/tools/perf/scripts/python/bin/syscall-counts-report
372
373#!/bin/bash
374# description: system-wide syscall counts
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100375perf script -s ~/libexec/perf-core/scripts/python/syscall-counts.py
Tom Zanussicff68e52010-01-27 02:28:03 -0600376----
377
378Note that the location of the Python script given in the shell script
379is in the libexec/perf-core/scripts/python directory - this is where
380the script will be copied by 'make install' when you install perf.
381For the installation to install your script there, your script needs
382to be located in the perf/scripts/python directory in the kernel
383source tree:
384
385----
386# ls -al kernel-source/tools/perf/scripts/python
387
388root@tropicana:/home/trz/src/tip# ls -al tools/perf/scripts/python
389total 32
390drwxr-xr-x 4 trz trz 4096 2010-01-26 22:30 .
391drwxr-xr-x 4 trz trz 4096 2010-01-26 22:29 ..
392drwxr-xr-x 2 trz trz 4096 2010-01-26 22:29 bin
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100393-rw-r--r-- 1 trz trz 2548 2010-01-26 22:29 check-perf-script.py
394drwxr-xr-x 3 trz trz 4096 2010-01-26 22:49 perf-script-Util
Tom Zanussicff68e52010-01-27 02:28:03 -0600395-rw-r--r-- 1 trz trz 1462 2010-01-26 22:30 syscall-counts.py
396----
397
398Once you've done that (don't forget to do a new 'make install',
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100399otherwise your script won't show up at run-time), 'perf script -l'
Tom Zanussicff68e52010-01-27 02:28:03 -0600400should show a new entry for your script:
401
402----
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100403root@tropicana:~# perf script -l
Tom Zanussicff68e52010-01-27 02:28:03 -0600404List of available trace scripts:
405 workqueue-stats workqueue stats (ins/exe/create/destroy)
406 wakeup-latency system-wide min/max/avg wakeup latency
407 rw-by-file <comm> r/w activity for a program, by file
408 rw-by-pid system-wide r/w activity
409 syscall-counts system-wide syscall counts
410----
411
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100412You can now perform the record step via 'perf script record':
Tom Zanussicff68e52010-01-27 02:28:03 -0600413
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100414 # perf script record syscall-counts
Tom Zanussicff68e52010-01-27 02:28:03 -0600415
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100416and display the output using 'perf script report':
Tom Zanussicff68e52010-01-27 02:28:03 -0600417
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100418 # perf script report syscall-counts
Tom Zanussicff68e52010-01-27 02:28:03 -0600419
420STARTER SCRIPTS
421---------------
422
423You can quickly get started writing a script for a particular set of
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100424trace data by generating a skeleton script using 'perf script -g
Tom Zanussicff68e52010-01-27 02:28:03 -0600425python' in the same directory as an existing perf.data trace file.
426That will generate a starter script containing a handler for each of
427the event types in the trace file; it simply prints every available
428field for each event in the trace file.
429
430You can also look at the existing scripts in
431~/libexec/perf-core/scripts/python for typical examples showing how to
432do basic things like aggregate event data, print results, etc. Also,
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100433the check-perf-script.py script, while not interesting for its results,
Tom Zanussicff68e52010-01-27 02:28:03 -0600434attempts to exercise all of the main scripting features.
435
436EVENT HANDLERS
437--------------
438
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100439When perf script is invoked using a trace script, a user-defined
Tom Zanussicff68e52010-01-27 02:28:03 -0600440'handler function' is called for each event in the trace. If there's
441no handler function defined for a given event type, the event is
442ignored (or passed to a 'trace_handled' function, see below) and the
443next event is processed.
444
445Most of the event's field values are passed as arguments to the
446handler function; some of the less common ones aren't - those are
447available as calls back into the perf executable (see below).
448
449As an example, the following perf record command can be used to record
450all sched_wakeup events in the system:
451
Frederic Weisbeckere5a5f1f2010-04-30 19:55:00 +0200452 # perf record -a -e sched:sched_wakeup
Tom Zanussicff68e52010-01-27 02:28:03 -0600453
454Traces meant to be processed using a script should be recorded with
Frederic Weisbeckere5a5f1f2010-04-30 19:55:00 +0200455the above option: -a to enable system-wide collection.
Tom Zanussicff68e52010-01-27 02:28:03 -0600456
457The format file for the sched_wakep event defines the following fields
458(see /sys/kernel/debug/tracing/events/sched/sched_wakeup/format):
459
460----
461 format:
462 field:unsigned short common_type;
463 field:unsigned char common_flags;
464 field:unsigned char common_preempt_count;
465 field:int common_pid;
466 field:int common_lock_depth;
467
468 field:char comm[TASK_COMM_LEN];
469 field:pid_t pid;
470 field:int prio;
471 field:int success;
472 field:int target_cpu;
473----
474
475The handler function for this event would be defined as:
476
477----
478def sched__sched_wakeup(event_name, context, common_cpu, common_secs,
479 common_nsecs, common_pid, common_comm,
480 comm, pid, prio, success, target_cpu):
481 pass
482----
483
484The handler function takes the form subsystem__event_name.
485
486The common_* arguments in the handler's argument list are the set of
487arguments passed to all event handlers; some of the fields correspond
488to the common_* fields in the format file, but some are synthesized,
489and some of the common_* fields aren't common enough to to be passed
490to every event as arguments but are available as library functions.
491
492Here's a brief description of each of the invariant event args:
493
494 event_name the name of the event as text
495 context an opaque 'cookie' used in calls back into perf
496 common_cpu the cpu the event occurred on
497 common_secs the secs portion of the event timestamp
498 common_nsecs the nsecs portion of the event timestamp
499 common_pid the pid of the current task
500 common_comm the name of the current process
501
502All of the remaining fields in the event's format file have
503counterparts as handler function arguments of the same name, as can be
504seen in the example above.
505
506The above provides the basics needed to directly access every field of
507every event in a trace, which covers 90% of what you need to know to
508write a useful trace script. The sections below cover the rest.
509
510SCRIPT LAYOUT
511-------------
512
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100513Every perf script Python script should start by setting up a Python
Tom Zanussicff68e52010-01-27 02:28:03 -0600514module search path and 'import'ing a few support modules (see module
515descriptions below):
516
517----
518 import os
519 import sys
520
521 sys.path.append(os.environ['PERF_EXEC_PATH'] + \
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100522 '/scripts/python/perf-script-Util/lib/Perf/Trace')
Tom Zanussicff68e52010-01-27 02:28:03 -0600523
524 from perf_trace_context import *
525 from Core import *
526----
527
528The rest of the script can contain handler functions and support
529functions in any order.
530
531Aside from the event handler functions discussed above, every script
532can implement a set of optional functions:
533
534*trace_begin*, if defined, is called before any event is processed and
535gives scripts a chance to do setup tasks:
536
537----
538def trace_begin:
539 pass
540----
541
542*trace_end*, if defined, is called after all events have been
543 processed and gives scripts a chance to do end-of-script tasks, such
544 as display results:
545
546----
547def trace_end:
548 pass
549----
550
551*trace_unhandled*, if defined, is called after for any event that
552 doesn't have a handler explicitly defined for it. The standard set
553 of common arguments are passed into it:
554
555----
556def trace_unhandled(event_name, context, common_cpu, common_secs,
557 common_nsecs, common_pid, common_comm):
558 pass
559----
560
561The remaining sections provide descriptions of each of the available
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100562built-in perf script Python modules and their associated functions.
Tom Zanussicff68e52010-01-27 02:28:03 -0600563
564AVAILABLE MODULES AND FUNCTIONS
565-------------------------------
566
567The following sections describe the functions and variables available
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100568via the various perf script Python modules. To use the functions and
Tom Zanussicff68e52010-01-27 02:28:03 -0600569variables from the given module, add the corresponding 'from XXXX
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100570import' line to your perf script script.
Tom Zanussicff68e52010-01-27 02:28:03 -0600571
572Core.py Module
573~~~~~~~~~~~~~~
574
575These functions provide some essential functions to user scripts.
576
577The *flag_str* and *symbol_str* functions provide human-readable
578strings for flag and symbolic fields. These correspond to the strings
579and values parsed from the 'print fmt' fields of the event format
580files:
581
582 flag_str(event_name, field_name, field_value) - returns the string represention corresponding to field_value for the flag field field_name of event event_name
583 symbol_str(event_name, field_name, field_value) - returns the string represention corresponding to field_value for the symbolic field field_name of event event_name
584
Kirill Smelkov5d2be7c2010-05-13 14:39:25 +0400585The *autodict* function returns a special kind of Python
Tom Zanussicff68e52010-01-27 02:28:03 -0600586dictionary that implements Perl's 'autovivifying' hashes in Python
587i.e. with autovivifying hashes, you can assign nested hash values
588without having to go to the trouble of creating intermediate levels if
589they don't exist.
590
591 autodict() - returns an autovivifying dictionary instance
592
593
594perf_trace_context Module
595~~~~~~~~~~~~~~~~~~~~~~~~~
596
597Some of the 'common' fields in the event format file aren't all that
598common, but need to be made accessible to user scripts nonetheless.
599
600perf_trace_context defines a set of functions that can be used to
601access this data in the context of the current event. Each of these
602functions expects a context variable, which is the same as the
603context variable passed into every event handler as the second
604argument.
605
606 common_pc(context) - returns common_preempt count for the current event
607 common_flags(context) - returns common_flags for the current event
608 common_lock_depth(context) - returns common_lock_depth for the current event
609
610Util.py Module
611~~~~~~~~~~~~~~
612
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100613Various utility functions for use with perf script:
Tom Zanussicff68e52010-01-27 02:28:03 -0600614
615 nsecs(secs, nsecs) - returns total nsecs given secs/nsecs pair
616 nsecs_secs(nsecs) - returns whole secs portion given nsecs
617 nsecs_nsecs(nsecs) - returns nsecs remainder given nsecs
618 nsecs_str(nsecs) - returns printable string in the form secs.nsecs
619 avg(total, n) - returns average given a sum and a total number of values
Tom Zanussicff68e52010-01-27 02:28:03 -0600620
621SEE ALSO
622--------
Ingo Molnar133dc4c2010-11-16 18:45:39 +0100623linkperf:perf-script[1]