On Mon, Nov 30, 2009 at 11:40 AM, Lindo Lonappan <li...@tataelxsi.co.in> wrote: > Dear all, > > We are using IDirectFBSurface::Blit() call for surface rotation. > Our hardware doesn't support surface rotation. We are using the software > fall back provided by DFB-1.4.2 for this. > > We observe that surface rotation is faster if we create surface in the > system memory. There is an extra time of 200ms for rotation if we create > surface in video memory. > But since we have hardware fall back for other operations we need to use the > video memory. They will have better performance in video memory. > > 1. why the rotation in system memory faster than video memory?
Probably because video memory is mapped uncached (that's usely the case with frame buffers). > 2. We guess in the case of video memory there is some overhead of switching > between kernel and user space since we are using a software fall back for > rotation. Is this is correct? There is no switch kernel/user when using the software fallback. > 3. Is there any way of creating surface which will not have any performance > difference in both hardware and software fall back? > (ie We need to create a surface which will give a performance of system > memory for surface rotation and a performance of video memory for operations > supported by our hardware.) You will have to use cached mapping for your buffers and correctly manage cache synchronization in your gfxdriver. > > Thanks a lot in advance!!! > Good luck. > -- > Thanks & Regards, > Lindo Lonappan. -- Lionel Landwerlin _______________________________________________ directfb-dev mailing list directfb-dev@directfb.org http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-dev
