PDA

View Full Version : how to do profiling for linux kernel or current kernel?



zerop2
July 10th, 2015, 07:12 AM
how to do profiling for linux kernel?
how to search which part of code in kernel code running the top 10 frequently and top 10 time consuming?


i search oprofile, how to use them to show?


http://homepages.cwi.nl/~aeb/linux/profile.html


after ./configure, make, sudo make install, opcontrol command not found

do it need to make install the new kernel in order to use oprofile


can it do profile for current kernel without installing new kernel

kerry_s
July 10th, 2015, 07:51 AM
use your editor as root & edit /etc/default/grub
i don't know what *ubuntu version your using so i'm going to assume standard ubuntu.

in terminal:
gksudo gedit /etc/default/grub

change line 11:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash profile"

save & close

still in terminal run:
sudo update-grub

reboot your computer, boot might take longer than normal.

zerop2
July 10th, 2015, 11:11 AM
i mean that i would like to edit kernel code, this method seems automatically fasten the boot times
is there any output or report to show where in the kernel code?

kerry_s
July 10th, 2015, 11:16 AM
you mean you want to compile your own kernel.
https://wiki.ubuntu.com/Kernel/BuildYourOwnKernel

tgalati4
July 10th, 2015, 03:33 PM
To find out where opcontrol is located:


which opcontrol

To start the profiling daemon (background process):


sudo opcontrol --start-daemon

It appears that opcontrol simply reads a device file /proc/profile, so you can enable profiling on several kernels on your system and whatever kernel that you are currently running, the /proc/profile will be for that current session. It gets rewritten for each boot. It is up to you to save the statistics during each session. So, boot up, select a profile-enabled kernel, run the oprofile configuration for the data that you want to collect, start the opcontrol daemon (above), run a standard workload, then print out the results. The tutorial is straight forward.

Yes, you need to install a new, instrumented (profiled) kernel alongside your existing kernel. Boot into GRUB2 and select the instrumented kernel.