Skip to content

Using oprofile

Oprofile is a profiling tool that requires no instrumentation and can profile an entire system. Binaries with symbol tables (-g compiled binaries) and an uncompressed Kernel with symbol table are helpful.

Oprofile is capable of monitoring and analyzing a running -g compiled mysqld and can tell you which functions are using the most CPU time.

Sample output:
CPU: CPU with timer interrupt, speed 0 MHz (estimated)
Profiling through timer interrupt
samples  %        image name               symbol name
197404   22.4460            memcpy
165764   18.8484  no-vmlinux               (no symbols)
76051     8.6475  mysqld.debug             _mi_rec_unpack
30059     3.4179  mysqld.debug             Query_cache::insert_into_
           (Query_cache_block*, Query_cache_block**)
17468     1.9862  mysqld.debug             get_hash_link
16767     1.9065  mysqld.debug             ha_key_cmp
14106     1.6039  mysqld.debug             MYSQLparse(void*)

A short cheatsheet:

  • yum install oprofile (or whatever in your system installs a package)
  • opcontrol --init
    Load kernel module oprofile
  • opcontrol --setup --separate=lib,kernel,thread --no-vmlinux
    Select how to collect data, unfortunately CentOS here does not provide a vmlinux kernel image. If you know how to reliably convert a vmlinuz image into a vmlinux image that is being accepted by oprofile, I'd like to hear that.
  • opcontrol --start-daemon
    Preload the kernel collection daemon
  • ps axuwww| grep opro
    Double check that the daemon is running
  • opcontrol --start
    Start data collection
  • opcontrol --dump
    Force data to disk
  • opreport --demangle=smart --symbols --long-filenames --merge tgid $(which mysqld) | less
    Get a report as above (-g binary req'd)
  • opcontrol --stop
    Stop profiling
  • opcontrol --deinit
    Stop daemon
  • opcontrol --reset
    Delete collected data, free disk space


bonglonglong on : OProfile, Kernel Images and InnoDB (oh my!)

Kristian Köhntopp has a wonderful article about using oprofile to track down problems in running programs. I thought I’d add a few thoughts. If you need to get a vmlinux kernel on redhat, apparently you just need to install kernel-debuginfo, whi...


Display comments as Linear | Threaded

John Levon on :

-g is /not/ required for what you're doing. You only need to keep the symtab
(don't use strip on the binary).

Add Comment

E-Mail addresses will not be displayed and will only be used for E-Mail notifications.

To prevent automated Bots from commentspamming, please enter the string you see in the image below in the appropriate input box. Your comment will only be submitted if the strings match. Please ensure that your browser supports and accepts cookies, or your comment cannot be verified correctly.

BBCode format allowed