Best practice tracking mobile website

Hello,

I would like to know, what ist the best practice for tracking users from desktop and mobile devices.
I need to know, how many times a specific page, for example /jobs/, was called from a mobile device compared to the views from the desktop mode.
Should I create two websites in PIWIK backend, with two tracking codes, one for www.mysite.com and another one for m.mysite.com?

Thanks for the support,
Ivaylo