oprofile a system wide profiler

oprofile a system wide profiler

** What is oprofile

In short “oprofile is a system-wide profiler”
need to profile an application and its shared libraries, examine hardware effects such as cache misses and capture the performance behaviour of entire system, then surely you need go with oprofile.

There is to many options and conditions spcefied, where we use only simple and easy one for further details, Please Read Man Pages 😉

Many CPUs provide “performance counters”, hardware registers that can count “events”; for example, cache misses, or CPU cycles. OProfile provides profiles of code based on the number of these occurring events: repeatedly, every time a certain (configurable) number of events has occurred, the PC value is recorded. This information is aggregated into profiles for each binary image.

Some hardware setups do not allow OProfile to use performance counters: in these cases, no events are available, and OProfile operates in timer/RTC mode

** All Docs, Examples and Bugs you will find @ http://oprofile.sourceforge.net

# download tar from http://oprofile.sourceforge.net/download/ or you can install it using yum also

[root@ravi.com ~]# yum install oprofile

Before you can use OProfile, you must set it up. The minimum setup required for this is to tell OProfile where the vmlinux file corresponding to the running kernel is, for example :

[root@ravi.com ~]#  opcontrol –vmlinux=/boot/vmlinux-`uname -r`

If you don’t want to profile the kernel itself, you can tell OProfile you don’t have a vmlinux file :

[root@ravi.com ~]# opcontrol –no-vmlinux

Here we used –no-vmlinux and specified other session directory than default location (/var/lib/oprofile)

[root@ravi.com ~]# opcontrol –no-vmlinux –session-dir=/home/prod/tmpsession

Now we are ready to start the daemon (oprofiled) which collects the profile data :

[root@ravi.com ~]# opcontrol –start –session-dir=/home/prod/tmpsession
Using default event: GLOBAL_POWER_EVENTS:100000:1:1:1
Using 2.6+ OProfile kernel interface.
Using log file /home/prod/tmpsession/samples/oprofiled.log
Daemon started.
Profiler running.

When I want to stop profiling, I can do so with :
(Here I have ran opcontrol only 1 min)
[root@ravi.com ~]# opcontrol –shutdown
Stopping profiling.
Killing daemon.

Lets see what your system & apps tell you 🙂
ophelp : This utility lists the available events and short descriptions.

[root@ravi.com ~]# opreport –session-dir=/home/prod/tmpsession
CPU: P4 / Xeon with 2 hyper-threads, speed 2992.73 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
GLOBAL_POWER_E…|
samples|      %|
——————
1109031 51.2560 no-vmlinux
479089 22.1420 libc-2.5.so
207263  9.5791 libperl.so
97973  4.5280 libpython2.4.so.1.0
91993  4.2516 nagios
35979  1.6628 php
35765  1.6529 libz.so.1.2.3
25203  1.1648 ld-2.5.so
21412  0.9896 mysqld
11566  0.5345 libgd.so.2.0.0
10008  0.4625 oprofiled
7661  0.3541 libpthread-2.5.so
6736  0.3113 libnetsnmp.so.10.0.3
5698  0.2633 libpng12.so.0.10.0
4488  0.2074 rateup
3500  0.1618 libcrypto.so.0.9.8e
2138  0.0988 bash
1556  0.0719 libm-2.5.so
1234  0.0570 libmysqlclient.so.15.0.0
606  0.0280 libpcre.so.0.0.1
328  0.0152 mysql.so
316  0.0146 librrd.so.4.1.3
290  0.0134 atop
272  0.0126 sendmail.sendmail
243  0.0112 grep
176  0.0081 nscd
172  0.0079 ping
153  0.0071 nebmodBY0Y2I (deleted)
144  0.0067 libgnutls.so.13.0.6
121  0.0056 init
106  0.0049 gawk

with using symbols you can simply find which apps supporting module takes high load
[root@ravi.com ~]#  opreport –exclude-dependent –symbols –long-filenames –session-dir=/home/prod/tmpsession
CPU: P4 / Xeon with 2 hyper-threads, speed 2992.73 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events (time during which processor is not stopped) with a unit mask of 0x01 (mandatory) count 100000
samples  %        app name                 symbol name
1109031  51.2560  /no-vmlinux              /no-vmlinux
209506    9.6827  /lib64/libc-2.5.so       _int_free
207263    9.5791  /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/libperl.so /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/libperl.so
97973     4.5280  /usr/lib64/libpython2.4.so.1.0 /usr/lib64/libpython2.4.so.1.0
91993     4.2516  /usr/local/nagios/bin/nagios /usr/local/nagios/bin/nagios
44574     2.0601  /lib64/libc-2.5.so       free
35765     1.6529  /usr/lib64/libz.so.1.2.3 /usr/lib64/libz.so.1.2.3
35032     1.6191  /lib64/libc-2.5.so       vfprintf
22061     1.0196  /lib64/libc-2.5.so       _IO_vfscanf
21412     0.9896  /usr/libexec/mysqld      /usr/libexec/mysqld
16883     0.7803  /lib64/libc-2.5.so       _int_malloc
13631     0.6300  /lib64/libc-2.5.so       memcpy
13165     0.6084  /lib64/libc-2.5.so       _IO_file_xsputn@@GLIBC_2.2.5
1560      0.0721  /lib64/ld-2.5.so         _dl_relocate_object
1462      0.0676  /usr/bin/php             lstep
1385      0.0640  /usr/bin/php             zend_do_fcall_common_helper_SPEC
1258      0.0581  /lib64/libc-2.5.so       rawmemchr
1234      0.0570  /usr/lib64/mysql/libmysqlclient.so.15.0.0 /usr/lib64/mysql/libmysqlclient.so.15.0.0
1226      0.0567  /lib64/libc-2.5.so       realloc
1180      0.0545  /lib64/libc-2.5.so       __tzfile_compute
1156      0.0534  /lib64/ld-2.5.so         check_match.8509
1146      0.0530  /usr/bin/php             _zend_mm_free_int
1084      0.0501  /usr/bin/php             zend_hash_quick_find
1029      0.0476  /lib64/libc-2.5.so       __mpn_mul_1
747       0.0345  /lib64/libc-2.5.so       fgets
738       0.0341  /usr/bin/php             _zval_ptr_dtor

Ref: http://oprofile.sourceforge.net/doc/index.html

-Ravi

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