How to measure performance inside Kernel?

[michi1 at michaelblizek.twilightparadox.com]

Hi!

On 10:58 Thu 09 Feb     , Peter Senna Tschudin wrote:
...
> But I want to repeat the tests on specific portion of code, not on
> entire application. Is there a safe way of do something like:
> 
> start_bench ( ?? ); /* start measurement */
> 
> buf_ptr_end = q->bufs[q->num_buffers];
> 
> for (buf_ptr = q->bufs[0]; buf_ptr < buf_ptr_end; ++buf_ptr)
>        buf_ptr->state = VB2_BUF_STATE_DEQUEUED;
> 
> end_bench ( ?? ); /* end measurement */

Yes, you can do this. If you search for a way for time measurement, take a
look at include/linux/ktime.h .

> And is this the correct approach for testing the performance of
> specific portion of Kernel code?

Why not? I would be a be worried about how the cpu-cache effects the
measurement, especially because your benchmark already showed that a
significant time is spent there.

	-Michi
-- 
programing a layer 3+4 network protocol for mesh networks
see http://michaelblizek.twilightparadox.com