621 lines
23 KiB
Plaintext
621 lines
23 KiB
Plaintext
|
perf-script-python(1)
|
||
|
|
====================
|
||
|
|
|
||
|
|
NAME
|
||
|
|
----
|
||
|
|
perf-script-python - Process trace data with a Python script
|
||
|
|
|
||
|
|
SYNOPSIS
|
||
|
|
--------
|
||
|
|
[verse]
|
||
|
|
'perf script' [-s [Python]:script[.py] ]
|
||
|
|
|
||
|
|
DESCRIPTION
|
||
|
|
-----------
|
||
|
|
|
||
|
|
This perf script option is used to process perf script data using perf's
|
||
|
|
built-in Python interpreter. It reads and processes the input file and
|
||
|
|
displays the results of the trace analysis implemented in the given
|
||
|
|
Python script, if any.
|
||
|
|
|
||
|
|
A QUICK EXAMPLE
|
||
|
|
---------------
|
||
|
|
|
||
|
|
This section shows the process, start to finish, of creating a working
|
||
|
|
Python script that aggregates and extracts useful information from a
|
||
|
|
raw perf script stream. You can avoid reading the rest of this
|
||
|
|
document if an example is enough for you; the rest of the document
|
||
|
|
provides more details on each step and lists the library functions
|
||
|
|
available to script writers.
|
||
|
|
|
||
|
|
This example actually details the steps that were used to create the
|
||
|
|
'syscall-counts' script you see when you list the available perf script
|
||
|
|
scripts via 'perf script -l'. As such, this script also shows how to
|
||
|
|
integrate your script into the list of general-purpose 'perf script'
|
||
|
|
scripts listed by that command.
|
||
|
|
|
||
|
|
The syscall-counts script is a simple script, but demonstrates all the
|
||
|
|
basic ideas necessary to create a useful script. Here's an example
|
||
|
|
of its output (syscall names are not yet supported, they will appear
|
||
|
|
as numbers):
|
||
|
|
|
||
|
|
----
|
||
|
|
syscall events:
|
||
|
|
|
||
|
|
event count
|
||
|
|
---------------------------------------- -----------
|
||
|
|
sys_write 455067
|
||
|
|
sys_getdents 4072
|
||
|
|
sys_close 3037
|
||
|
|
sys_swapoff 1769
|
||
|
|
sys_read 923
|
||
|
|
sys_sched_setparam 826
|
||
|
|
sys_open 331
|
||
|
|
sys_newfstat 326
|
||
|
|
sys_mmap 217
|
||
|
|
sys_munmap 216
|
||
|
|
sys_futex 141
|
||
|
|
sys_select 102
|
||
|
|
sys_poll 84
|
||
|
|
sys_setitimer 12
|
||
|
|
sys_writev 8
|
||
|
|
15 8
|
||
|
|
sys_lseek 7
|
||
|
|
sys_rt_sigprocmask 6
|
||
|
|
sys_wait4 3
|
||
|
|
sys_ioctl 3
|
||
|
|
sys_set_robust_list 1
|
||
|
|
sys_exit 1
|
||
|
|
56 1
|
||
|
|
sys_access 1
|
||
|
|
----
|
||
|
|
|
||
|
|
Basically our task is to keep a per-syscall tally that gets updated
|
||
|
|
every time a system call occurs in the system. Our script will do
|
||
|
|
that, but first we need to record the data that will be processed by
|
||
|
|
that script. Theoretically, there are a couple of ways we could do
|
||
|
|
that:
|
||
|
|
|
||
|
|
- we could enable every event under the tracing/events/syscalls
|
||
|
|
directory, but this is over 600 syscalls, well beyond the number
|
||
|
|
allowable by perf. These individual syscall events will however be
|
||
|
|
useful if we want to later use the guidance we get from the
|
||
|
|
general-purpose scripts to drill down and get more detail about
|
||
|
|
individual syscalls of interest.
|
||
|
|
|
||
|
|
- we can enable the sys_enter and/or sys_exit syscalls found under
|
||
|
|
tracing/events/raw_syscalls. These are called for all syscalls; the
|
||
|
|
'id' field can be used to distinguish between individual syscall
|
||
|
|
numbers.
|
||
|
|
|
||
|
|
For this script, we only need to know that a syscall was entered; we
|
||
|
|
don't care how it exited, so we'll use 'perf record' to record only
|
||
|
|
the sys_enter events:
|
||
|
|
|
||
|
|
----
|
||
|
|
# perf record -a -e raw_syscalls:sys_enter
|
||
|
|
|
||
|
|
^C[ perf record: Woken up 1 times to write data ]
|
||
|
|
[ perf record: Captured and wrote 56.545 MB perf.data (~2470503 samples) ]
|
||
|
|
----
|
||
|
|
|
||
|
|
The options basically say to collect data for every syscall event
|
||
|
|
system-wide and multiplex the per-cpu output into a single stream.
|
||
|
|
That single stream will be recorded in a file in the current directory
|
||
|
|
called perf.data.
|
||
|
|
|
||
|
|
Once we have a perf.data file containing our data, we can use the -g
|
||
|
|
'perf script' option to generate a Python script that will contain a
|
||
|
|
callback handler for each event type found in the perf.data trace
|
||
|
|
stream (for more details, see the STARTER SCRIPTS section).
|
||
|
|
|
||
|
|
----
|
||
|
|
# perf script -g python
|
||
|
|
generated Python script: perf-script.py
|
||
|
|
|
||
|
|
The output file created also in the current directory is named
|
||
|
|
perf-script.py. Here's the file in its entirety:
|
||
|
|
|
||
|
|
# perf script event handlers, generated by perf script -g python
|
||
|
|
# Licensed under the terms of the GNU GPL License version 2
|
||
|
|
|
||
|
|
# The common_* event handler fields are the most useful fields common to
|
||
|
|
# all events. They don't necessarily correspond to the 'common_*' fields
|
||
|
|
# in the format files. Those fields not available as handler params can
|
||
|
|
# be retrieved using Python functions of the form common_*(context).
|
||
|
|
# See the perf-script-python Documentation for the list of available functions.
|
||
|
|
|
||
|
|
import os
|
||
|
|
import sys
|
||
|
|
|
||
|
|
sys.path.append(os.environ['PERF_EXEC_PATH'] + \
|
||
|
|
'/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
|
||
|
|
|
||
|
|
from perf_trace_context import *
|
||
|
|
from Core import *
|
||
|
|
|
||
|
|
def trace_begin():
|
||
|
|
print "in trace_begin"
|
||
|
|
|
||
|
|
def trace_end():
|
||
|
|
print "in trace_end"
|
||
|
|
|
||
|
|
def raw_syscalls__sys_enter(event_name, context, common_cpu,
|
||
|
|
common_secs, common_nsecs, common_pid, common_comm,
|
||
|
|
id, args):
|
||
|
|
print_header(event_name, common_cpu, common_secs, common_nsecs,
|
||
|
|
common_pid, common_comm)
|
||
|
|
|
||
|
|
print "id=%d, args=%s\n" % \
|
||
|
|
(id, args),
|
||
|
|
|
||
|
|
def trace_unhandled(event_name, context, common_cpu, common_secs, common_nsecs,
|
||
|
|
common_pid, common_comm):
|
||
|
|
print_header(event_name, common_cpu, common_secs, common_nsecs,
|
||
|
|
common_pid, common_comm)
|
||
|
|
|
||
|
|
def print_header(event_name, cpu, secs, nsecs, pid, comm):
|
||
|
|
print "%-20s %5u %05u.%09u %8u %-20s " % \
|
||
|
|
(event_name, cpu, secs, nsecs, pid, comm),
|
||
|
|
----
|
||
|
|
|
||
|
|
At the top is a comment block followed by some import statements and a
|
||
|
|
path append which every perf script script should include.
|
||
|
|
|
||
|
|
Following that are a couple generated functions, trace_begin() and
|
||
|
|
trace_end(), which are called at the beginning and the end of the
|
||
|
|
script respectively (for more details, see the SCRIPT_LAYOUT section
|
||
|
|
below).
|
||
|
|
|
||
|
|
Following those are the 'event handler' functions generated one for
|
||
|
|
every event in the 'perf record' output. The handler functions take
|
||
|
|
the form subsystem__event_name, and contain named parameters, one for
|
||
|
|
each field in the event; in this case, there's only one event,
|
||
|
|
raw_syscalls__sys_enter(). (see the EVENT HANDLERS section below for
|
||
|
|
more info on event handlers).
|
||
|
|
|
||
|
|
The final couple of functions are, like the begin and end functions,
|
||
|
|
generated for every script. The first, trace_unhandled(), is called
|
||
|
|
every time the script finds an event in the perf.data file that
|
||
|
|
doesn't correspond to any event handler in the script. This could
|
||
|
|
mean either that the record step recorded event types that it wasn't
|
||
|
|
really interested in, or the script was run against a trace file that
|
||
|
|
doesn't correspond to the script.
|
||
|
|
|
||
|
|
The script generated by -g option simply prints a line for each
|
||
|
|
event found in the trace stream i.e. it basically just dumps the event
|
||
|
|
and its parameter values to stdout. The print_header() function is
|
||
|
|
simply a utility function used for that purpose. Let's rename the
|
||
|
|
script and run it to see the default output:
|
||
|
|
|
||
|
|
----
|
||
|
|
# mv perf-script.py syscall-counts.py
|
||
|
|
# perf script -s syscall-counts.py
|
||
|
|
|
||
|
|
raw_syscalls__sys_enter 1 00840.847582083 7506 perf id=1, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847595764 7506 perf id=1, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847620860 7506 perf id=1, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847710478 6533 npviewer.bin id=78, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847719204 6533 npviewer.bin id=142, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847755445 6533 npviewer.bin id=3, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847775601 6533 npviewer.bin id=3, args=
|
||
|
|
raw_syscalls__sys_enter 1 00840.847781820 6533 npviewer.bin id=3, args=
|
||
|
|
.
|
||
|
|
.
|
||
|
|
.
|
||
|
|
----
|
||
|
|
|
||
|
|
Of course, for this script, we're not interested in printing every
|
||
|
|
trace event, but rather aggregating it in a useful way. So we'll get
|
||
|
|
rid of everything to do with printing as well as the trace_begin() and
|
||
|
|
trace_unhandled() functions, which we won't be using. That leaves us
|
||
|
|
with this minimalistic skeleton:
|
||
|
|
|
||
|
|
----
|
||
|
|
import os
|
||
|
|
import sys
|
||
|
|
|
||
|
|
sys.path.append(os.environ['PERF_EXEC_PATH'] + \
|
||
|
|
'/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
|
||
|
|
|
||
|
|
from perf_trace_context import *
|
||
|
|
from Core import *
|
||
|
|
|
||
|
|
def trace_end():
|
||
|
|
print "in trace_end"
|
||
|
|
|
||
|
|
def raw_syscalls__sys_enter(event_name, context, common_cpu,
|
||
|
|
common_secs, common_nsecs, common_pid, common_comm,
|
||
|
|
id, args):
|
||
|
|
----
|
||
|
|
|
||
|
|
In trace_end(), we'll simply print the results, but first we need to
|
||
|
|
generate some results to print. To do that we need to have our
|
||
|
|
sys_enter() handler do the necessary tallying until all events have
|
||
|
|
been counted. A hash table indexed by syscall id is a good way to
|
||
|
|
store that information; every time the sys_enter() handler is called,
|
||
|
|
we simply increment a count associated with that hash entry indexed by
|
||
|
|
that syscall id:
|
||
|
|
|
||
|
|
----
|
||
|
|
syscalls = autodict()
|
||
|
|
|
||
|
|
try:
|
||
|
|
syscalls[id] += 1
|
||
|
|
except TypeError:
|
||
|
|
syscalls[id] = 1
|
||
|
|
----
|
||
|
|
|
||
|
|
The syscalls 'autodict' object is a special kind of Python dictionary
|
||
|
|
(implemented in Core.py) that implements Perl's 'autovivifying' hashes
|
||
|
|
in Python i.e. with autovivifying hashes, you can assign nested hash
|
||
|
|
values without having to go to the trouble of creating intermediate
|
||
|
|
levels if they don't exist e.g syscalls[comm][pid][id] = 1 will create
|
||
|
|
the intermediate hash levels and finally assign the value 1 to the
|
||
|
|
hash entry for 'id' (because the value being assigned isn't a hash
|
||
|
|
object itself, the initial value is assigned in the TypeError
|
||
|
|
exception. Well, there may be a better way to do this in Python but
|
||
|
|
that's what works for now).
|
||
|
|
|
||
|
|
Putting that code into the raw_syscalls__sys_enter() handler, we
|
||
|
|
effectively end up with a single-level dictionary keyed on syscall id
|
||
|
|
and having the counts we've tallied as values.
|
||
|
|
|
||
|
|
The print_syscall_totals() function iterates over the entries in the
|
||
|
|
dictionary and displays a line for each entry containing the syscall
|
||
|
|
name (the dictionary keys contain the syscall ids, which are passed to
|
||
|
|
the Util function syscall_name(), which translates the raw syscall
|
||
|
|
numbers to the corresponding syscall name strings). The output is
|
||
|
|
displayed after all the events in the trace have been processed, by
|
||
|
|
calling the print_syscall_totals() function from the trace_end()
|
||
|
|
handler called at the end of script processing.
|
||
|
|
|
||
|
|
The final script producing the output shown above is shown in its
|
||
|
|
entirety below (syscall_name() helper is not yet available, you can
|
||
|
|
only deal with id's for now):
|
||
|
|
|
||
|
|
----
|
||
|
|
import os
|
||
|
|
import sys
|
||
|
|
|
||
|
|
sys.path.append(os.environ['PERF_EXEC_PATH'] + \
|
||
|
|
'/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
|
||
|
|
|
||
|
|
from perf_trace_context import *
|
||
|
|
from Core import *
|
||
|
|
from Util import *
|
||
|
|
|
||
|
|
syscalls = autodict()
|
||
|
|
|
||
|
|
def trace_end():
|
||
|
|
print_syscall_totals()
|
||
|
|
|
||
|
|
def raw_syscalls__sys_enter(event_name, context, common_cpu,
|
||
|
|
common_secs, common_nsecs, common_pid, common_comm,
|
||
|
|
id, args):
|
||
|
|
try:
|
||
|
|
syscalls[id] += 1
|
||
|
|
except TypeError:
|
||
|
|
syscalls[id] = 1
|
||
|
|
|
||
|
|
def print_syscall_totals():
|
||
|
|
if for_comm is not None:
|
||
|
|
print "\nsyscall events for %s:\n\n" % (for_comm),
|
||
|
|
else:
|
||
|
|
print "\nsyscall events:\n\n",
|
||
|
|
|
||
|
|
print "%-40s %10s\n" % ("event", "count"),
|
||
|
|
print "%-40s %10s\n" % ("----------------------------------------", \
|
||
|
|
"-----------"),
|
||
|
|
|
||
|
|
for id, val in sorted(syscalls.iteritems(), key = lambda(k, v): (v, k), \
|
||
|
|
reverse = True):
|
||
|
|
print "%-40s %10d\n" % (syscall_name(id), val),
|
||
|
|
----
|
||
|
|
|
||
|
|
The script can be run just as before:
|
||
|
|
|
||
|
|
# perf script -s syscall-counts.py
|
||
|
|
|
||
|
|
So those are the essential steps in writing and running a script. The
|
||
|
|
process can be generalized to any tracepoint or set of tracepoints
|
||
|
|
you're interested in - basically find the tracepoint(s) you're
|
||
|
|
interested in by looking at the list of available events shown by
|
||
|
|
'perf list' and/or look in /sys/kernel/debug/tracing events for
|
||
|
|
detailed event and field info, record the corresponding trace data
|
||
|
|
using 'perf record', passing it the list of interesting events,
|
||
|
|
generate a skeleton script using 'perf script -g python' and modify the
|
||
|
|
code to aggregate and display it for your particular needs.
|
||
|
|
|
||
|
|
After you've done that you may end up with a general-purpose script
|
||
|
|
that you want to keep around and have available for future use. By
|
||
|
|
writing a couple of very simple shell scripts and putting them in the
|
||
|
|
right place, you can have your script listed alongside the other
|
||
|
|
scripts listed by the 'perf script -l' command e.g.:
|
||
|
|
|
||
|
|
----
|
||
|
|
root@tropicana:~# perf script -l
|
||
|
|
List of available trace scripts:
|
||
|
|
wakeup-latency system-wide min/max/avg wakeup latency
|
||
|
|
rw-by-file <comm> r/w activity for a program, by file
|
||
|
|
rw-by-pid system-wide r/w activity
|
||
|
|
----
|
||
|
|
|
||
|
|
A nice side effect of doing this is that you also then capture the
|
||
|
|
probably lengthy 'perf record' command needed to record the events for
|
||
|
|
the script.
|
||
|
|
|
||
|
|
To have the script appear as a 'built-in' script, you write two simple
|
||
|
|
scripts, one for recording and one for 'reporting'.
|
||
|
|
|
||
|
|
The 'record' script is a shell script with the same base name as your
|
||
|
|
script, but with -record appended. The shell script should be put
|
||
|
|
into the perf/scripts/python/bin directory in the kernel source tree.
|
||
|
|
In that script, you write the 'perf record' command-line needed for
|
||
|
|
your script:
|
||
|
|
|
||
|
|
----
|
||
|
|
# cat kernel-source/tools/perf/scripts/python/bin/syscall-counts-record
|
||
|
|
|
||
|
|
#!/bin/bash
|
||
|
|
perf record -a -e raw_syscalls:sys_enter
|
||
|
|
----
|
||
|
|
|
||
|
|
The 'report' script is also a shell script with the same base name as
|
||
|
|
your script, but with -report appended. It should also be located in
|
||
|
|
the perf/scripts/python/bin directory. In that script, you write the
|
||
|
|
'perf script -s' command-line needed for running your script:
|
||
|
|
|
||
|
|
----
|
||
|
|
# cat kernel-source/tools/perf/scripts/python/bin/syscall-counts-report
|
||
|
|
|
||
|
|
#!/bin/bash
|
||
|
|
# description: system-wide syscall counts
|
||
|
|
perf script -s ~/libexec/perf-core/scripts/python/syscall-counts.py
|
||
|
|
----
|
||
|
|
|
||
|
|
Note that the location of the Python script given in the shell script
|
||
|
|
is in the libexec/perf-core/scripts/python directory - this is where
|
||
|
|
the script will be copied by 'make install' when you install perf.
|
||
|
|
For the installation to install your script there, your script needs
|
||
|
|
to be located in the perf/scripts/python directory in the kernel
|
||
|
|
source tree:
|
||
|
|
|
||
|
|
----
|
||
|
|
# ls -al kernel-source/tools/perf/scripts/python
|
||
|
|
|
||
|
|
root@tropicana:/home/trz/src/tip# ls -al tools/perf/scripts/python
|
||
|
|
total 32
|
||
|
|
drwxr-xr-x 4 trz trz 4096 2010-01-26 22:30 .
|
||
|
|
drwxr-xr-x 4 trz trz 4096 2010-01-26 22:29 ..
|
||
|
|
drwxr-xr-x 2 trz trz 4096 2010-01-26 22:29 bin
|
||
|
|
-rw-r--r-- 1 trz trz 2548 2010-01-26 22:29 check-perf-script.py
|
||
|
|
drwxr-xr-x 3 trz trz 4096 2010-01-26 22:49 Perf-Trace-Util
|
||
|
|
-rw-r--r-- 1 trz trz 1462 2010-01-26 22:30 syscall-counts.py
|
||
|
|
----
|
||
|
|
|
||
|
|
Once you've done that (don't forget to do a new 'make install',
|
||
|
|
otherwise your script won't show up at run-time), 'perf script -l'
|
||
|
|
should show a new entry for your script:
|
||
|
|
|
||
|
|
----
|
||
|
|
root@tropicana:~# perf script -l
|
||
|
|
List of available trace scripts:
|
||
|
|
wakeup-latency system-wide min/max/avg wakeup latency
|
||
|
|
rw-by-file <comm> r/w activity for a program, by file
|
||
|
|
rw-by-pid system-wide r/w activity
|
||
|
|
syscall-counts system-wide syscall counts
|
||
|
|
----
|
||
|
|
|
||
|
|
You can now perform the record step via 'perf script record':
|
||
|
|
|
||
|
|
# perf script record syscall-counts
|
||
|
|
|
||
|
|
and display the output using 'perf script report':
|
||
|
|
|
||
|
|
# perf script report syscall-counts
|
||
|
|
|
||
|
|
STARTER SCRIPTS
|
||
|
|
---------------
|
||
|
|
|
||
|
|
You can quickly get started writing a script for a particular set of
|
||
|
|
trace data by generating a skeleton script using 'perf script -g
|
||
|
|
python' in the same directory as an existing perf.data trace file.
|
||
|
|
That will generate a starter script containing a handler for each of
|
||
|
|
the event types in the trace file; it simply prints every available
|
||
|
|
field for each event in the trace file.
|
||
|
|
|
||
|
|
You can also look at the existing scripts in
|
||
|
|
~/libexec/perf-core/scripts/python for typical examples showing how to
|
||
|
|
do basic things like aggregate event data, print results, etc. Also,
|
||
|
|
the check-perf-script.py script, while not interesting for its results,
|
||
|
|
attempts to exercise all of the main scripting features.
|
||
|
|
|
||
|
|
EVENT HANDLERS
|
||
|
|
--------------
|
||
|
|
|
||
|
|
When perf script is invoked using a trace script, a user-defined
|
||
|
|
'handler function' is called for each event in the trace. If there's
|
||
|
|
no handler function defined for a given event type, the event is
|
||
|
|
ignored (or passed to a 'trace_handled' function, see below) and the
|
||
|
|
next event is processed.
|
||
|
|
|
||
|
|
Most of the event's field values are passed as arguments to the
|
||
|
|
handler function; some of the less common ones aren't - those are
|
||
|
|
available as calls back into the perf executable (see below).
|
||
|
|
|
||
|
|
As an example, the following perf record command can be used to record
|
||
|
|
all sched_wakeup events in the system:
|
||
|
|
|
||
|
|
# perf record -a -e sched:sched_wakeup
|
||
|
|
|
||
|
|
Traces meant to be processed using a script should be recorded with
|
||
|
|
the above option: -a to enable system-wide collection.
|
||
|
|
|
||
|
|
The format file for the sched_wakep event defines the following fields
|
||
|
|
(see /sys/kernel/debug/tracing/events/sched/sched_wakeup/format):
|
||
|
|
|
||
|
|
----
|
||
|
|
format:
|
||
|
|
field:unsigned short common_type;
|
||
|
|
field:unsigned char common_flags;
|
||
|
|
field:unsigned char common_preempt_count;
|
||
|
|
field:int common_pid;
|
||
|
|
|
||
|
|
field:char comm[TASK_COMM_LEN];
|
||
|
|
field:pid_t pid;
|
||
|
|
field:int prio;
|
||
|
|
field:int success;
|
||
|
|
field:int target_cpu;
|
||
|
|
----
|
||
|
|
|
||
|
|
The handler function for this event would be defined as:
|
||
|
|
|
||
|
|
----
|
||
|
|
def sched__sched_wakeup(event_name, context, common_cpu, common_secs,
|
||
|
|
common_nsecs, common_pid, common_comm,
|
||
|
|
comm, pid, prio, success, target_cpu):
|
||
|
|
pass
|
||
|
|
----
|
||
|
|
|
||
|
|
The handler function takes the form subsystem__event_name.
|
||
|
|
|
||
|
|
The common_* arguments in the handler's argument list are the set of
|
||
|
|
arguments passed to all event handlers; some of the fields correspond
|
||
|
|
to the common_* fields in the format file, but some are synthesized,
|
||
|
|
and some of the common_* fields aren't common enough to to be passed
|
||
|
|
to every event as arguments but are available as library functions.
|
||
|
|
|
||
|
|
Here's a brief description of each of the invariant event args:
|
||
|
|
|
||
|
|
event_name the name of the event as text
|
||
|
|
context an opaque 'cookie' used in calls back into perf
|
||
|
|
common_cpu the cpu the event occurred on
|
||
|
|
common_secs the secs portion of the event timestamp
|
||
|
|
common_nsecs the nsecs portion of the event timestamp
|
||
|
|
common_pid the pid of the current task
|
||
|
|
common_comm the name of the current process
|
||
|
|
|
||
|
|
All of the remaining fields in the event's format file have
|
||
|
|
counterparts as handler function arguments of the same name, as can be
|
||
|
|
seen in the example above.
|
||
|
|
|
||
|
|
The above provides the basics needed to directly access every field of
|
||
|
|
every event in a trace, which covers 90% of what you need to know to
|
||
|
|
write a useful trace script. The sections below cover the rest.
|
||
|
|
|
||
|
|
SCRIPT LAYOUT
|
||
|
|
-------------
|
||
|
|
|
||
|
|
Every perf script Python script should start by setting up a Python
|
||
|
|
module search path and 'import'ing a few support modules (see module
|
||
|
|
descriptions below):
|
||
|
|
|
||
|
|
----
|
||
|
|
import os
|
||
|
|
import sys
|
||
|
|
|
||
|
|
sys.path.append(os.environ['PERF_EXEC_PATH'] + \
|
||
|
|
'/scripts/python/Perf-Trace-Util/lib/Perf/Trace')
|
||
|
|
|
||
|
|
from perf_trace_context import *
|
||
|
|
from Core import *
|
||
|
|
----
|
||
|
|
|
||
|
|
The rest of the script can contain handler functions and support
|
||
|
|
functions in any order.
|
||
|
|
|
||
|
|
Aside from the event handler functions discussed above, every script
|
||
|
|
can implement a set of optional functions:
|
||
|
|
|
||
|
|
*trace_begin*, if defined, is called before any event is processed and
|
||
|
|
gives scripts a chance to do setup tasks:
|
||
|
|
|
||
|
|
----
|
||
|
|
def trace_begin:
|
||
|
|
pass
|
||
|
|
----
|
||
|
|
|
||
|
|
*trace_end*, if defined, is called after all events have been
|
||
|
|
processed and gives scripts a chance to do end-of-script tasks, such
|
||
|
|
as display results:
|
||
|
|
|
||
|
|
----
|
||
|
|
def trace_end:
|
||
|
|
pass
|
||
|
|
----
|
||
|
|
|
||
|
|
*trace_unhandled*, if defined, is called after for any event that
|
||
|
|
doesn't have a handler explicitly defined for it. The standard set
|
||
|
|
of common arguments are passed into it:
|
||
|
|
|
||
|
|
----
|
||
|
|
def trace_unhandled(event_name, context, common_cpu, common_secs,
|
||
|
|
common_nsecs, common_pid, common_comm):
|
||
|
|
pass
|
||
|
|
----
|
||
|
|
|
||
|
|
The remaining sections provide descriptions of each of the available
|
||
|
|
built-in perf script Python modules and their associated functions.
|
||
|
|
|
||
|
|
AVAILABLE MODULES AND FUNCTIONS
|
||
|
|
-------------------------------
|
||
|
|
|
||
|
|
The following sections describe the functions and variables available
|
||
|
|
via the various perf script Python modules. To use the functions and
|
||
|
|
variables from the given module, add the corresponding 'from XXXX
|
||
|
|
import' line to your perf script script.
|
||
|
|
|
||
|
|
Core.py Module
|
||
|
|
~~~~~~~~~~~~~~
|
||
|
|
|
||
|
|
These functions provide some essential functions to user scripts.
|
||
|
|
|
||
|
|
The *flag_str* and *symbol_str* functions provide human-readable
|
||
|
|
strings for flag and symbolic fields. These correspond to the strings
|
||
|
|
and values parsed from the 'print fmt' fields of the event format
|
||
|
|
files:
|
||
|
|
|
||
|
|
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
|
||
|
|
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
|
||
|
|
|
||
|
|
The *autodict* function returns a special kind of Python
|
||
|
|
dictionary that implements Perl's 'autovivifying' hashes in Python
|
||
|
|
i.e. with autovivifying hashes, you can assign nested hash values
|
||
|
|
without having to go to the trouble of creating intermediate levels if
|
||
|
|
they don't exist.
|
||
|
|
|
||
|
|
autodict() - returns an autovivifying dictionary instance
|
||
|
|
|
||
|
|
|
||
|
|
perf_trace_context Module
|
||
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~
|
||
|
|
|
||
|
|
Some of the 'common' fields in the event format file aren't all that
|
||
|
|
common, but need to be made accessible to user scripts nonetheless.
|
||
|
|
|
||
|
|
perf_trace_context defines a set of functions that can be used to
|
||
|
|
access this data in the context of the current event. Each of these
|
||
|
|
functions expects a context variable, which is the same as the
|
||
|
|
context variable passed into every event handler as the second
|
||
|
|
argument.
|
||
|
|
|
||
|
|
common_pc(context) - returns common_preempt count for the current event
|
||
|
|
common_flags(context) - returns common_flags for the current event
|
||
|
|
common_lock_depth(context) - returns common_lock_depth for the current event
|
||
|
|
|
||
|
|
Util.py Module
|
||
|
|
~~~~~~~~~~~~~~
|
||
|
|
|
||
|
|
Various utility functions for use with perf script:
|
||
|
|
|
||
|
|
nsecs(secs, nsecs) - returns total nsecs given secs/nsecs pair
|
||
|
|
nsecs_secs(nsecs) - returns whole secs portion given nsecs
|
||
|
|
nsecs_nsecs(nsecs) - returns nsecs remainder given nsecs
|
||
|
|
nsecs_str(nsecs) - returns printable string in the form secs.nsecs
|
||
|
|
avg(total, n) - returns average given a sum and a total number of values
|
||
|
|
|
||
|
|
SEE ALSO
|
||
|
|
--------
|
||
|
|
linkperf:perf-script[1]
|