Resources used by driver ?

Resources used by driver ?

[Guillaume Dargaud]

Thanks to the advice I received here, I now have my first 'real' Linux driver 
up and running and am now at the optimization stage.

Is it possible to see the resources consumed by a module ? They don't show in 
'ps/top' but I'm sure there are ways to see how much memory it uses (to check 
for memory leaks) and how much CPU it takes. How ?

Thanks
-- 
Guillaume Dargaud
http://www.gdargaud.net/Antarctica/

Re: Resources used by driver ?

[Michael Ellerman]

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On Thu, 2011-02-10 at 11:08 +0100, Guillaume Dargaud wrote:
> Thanks to the advice I received here, I now have my first 'real' Linux driver 
> up and running and am now at the optimization stage.
> 
> Is it possible to see the resources consumed by a module ? They don't show in 
> 'ps/top' but I'm sure there are ways to see how much memory it uses (to check 
> for memory leaks) and how much CPU it takes. How ?

Hi Guillaume,

It's actually not that easy to measure the resources used by a driver.
In general your driver code only runs on behalf of another process, and
so that process is where the cpu usage will be accounted.

One exception is if your driver spawns a kernel thread for something, in
that case you can see it with top.

For memory usage, you can monitor /proc/slabinfo and see if anything is
growing every time you access your driver. Another option is to enable
CONFIG_DEBUG_KMEMLEAK, which will try and detect real leaks for you.

cheers

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Re: Resources used by driver ?

[Guillaume Dargaud]

On Wednesday 16 February 2011 08:01:10 Srivatsan S wrote:
> You can use oprofile to profile the functions of your module. Follow the
> link.
> http://oprofile.sourceforge.net/ <http://oprofile.sourceforge.net/news/>

OK, after some wrestling, I got oprofile installed in my OS (buildroot 2011.02-
rc1) and my kernel (xilinx patches 2.6.35+).

When I start oprofile, I get the following:
# opcontrol --vmlinux=/vmlinux
The specified file /vmlinux does not seem to be valid
Make sure you are using the non-compressed image file (e.g. vmlinux not 
vmlinuz)

# file /vmlinux
/vmlinux: ELF 32-bit MSB executable, PowerPC or cisco 4500, version 1 (SYSV), 
statically linked, with unknown capability 0x41000000 = 0x11676e75, with 
unknown capability 0x10000 = 0x90402, not stripped

I used the vmlinux generated found in ../linus-2.6-xlnx/vmlinux
What's wrong with it ?
-- 
Guillaume Dargaud
http://www.gdargaud.net/

Re: Resources used by driver ?

[Guillaume Dargaud]

> When I start oprofile, I get the following:
> # opcontrol --vmlinux=/vmlinux
> The specified file /vmlinux does not seem to be valid
> Make sure you are using the non-compressed image file (e.g. vmlinux not
> vmlinuz)

Sorry, I had an incomplete install of objdump/binutils on my target. I'm now 
trying to understand how to use oprofile.
-- 
Guillaume Dargaud
http://www.gdargaud.net/