On Tue 9 April 2013 09:58:33 Michal Lazo wrote:
> I want to make API that will provide hw video decoder on Amlogic SOC
> it is ARM cortex 9
>
> with some proprietary video decoder
>
> amlogic provide me with working example that generate output frames in
> amlvideo driver.
> It is v4l2 driver
> and it did memcpy to mmap userspace memory
>
> buffer_y_start=ioremap(cs0.addr,cs0.width*cs0.height);
> for(i=0;i<buf->vb.height;i++) {
> memcpy(vbuf + pos_dst, buffer_y_start+pos_src, buf->vb.width*3);
> pos_dst+=buf->vb.width*3;
> pos_src+= cs0.width;
> }
>
> I did it with one memcpy with same cpu load
>
> https://github.com/Pivosgroup/buildroot-linux-kernel/blob/master/drivers/media/video/amlvideo/amlvideo.c#L218
>
> top get me 50% cpu load on this driver for 25fps PAL
>
> it is really too much
>
> and funny is that vivi driver(amlvideo is completely base on vivi) get
> me same cpu load
Well, yes, because it is the memcpy that gives you all the load.
Of course, in a well-written driver the amlvideo buffers would be available
to userspace directly using mmap() and no memcpy would be needed.
Basically amlogic gave you a crappy driver.
Regards,
Hans
>
> it looks like memcpy isn't cached or something but I don't know how to
> identify problem
> Any idea how to identify this problem.
>
> On Mon, Apr 8, 2013 at 2:46 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> > On Mon April 8 2013 14:42:32 Michal Lazo wrote:
> >> Hi
> >> 720x576 RGB 25, 30 fps and it take
> >>
> >> 25% cpu load on raspberry pi(ARM 700Mhz linux 3.6.11) or 8% on x86(AMD
> >> 2GHz linux 3.2.0-39)
> >>
> >> it is simply too much
> >
> > No, that's what I would expect. Note that vivi was substantially improved recently
> > when it comes to the image generation. That will be in the upcoming 3.9 kernel.
> >
> > This should reduce CPU load by quite a bit if memory serves.
> >
> > Regards,
> >
> > Hans
> >
> >>
> >>
> >>
> >>
> >> On Mon, Apr 8, 2013 at 9:42 AM, Peter Senna Tschudin
> >> <peter.senna@xxxxxxxxx> wrote:
> >> > Dear Michal,
> >> >
> >> > The CPU intensive part of the vivi driver is the image generation.
> >> > This is not an issue for real drivers.
> >> >
> >> > Regards,
> >> >
> >> > Peter
> >> >
> >> > On Sun, Apr 7, 2013 at 9:32 PM, Michal Lazo <michal.lazo@xxxxxxxxxxx> wrote:
> >> >> Hi
> >> >> V4L2 driver vivi
> >> >> generate 25% cpu load on raspberry pi(linux 3.6.11) or 8% on x86(linux 3.2.0-39)
> >> >>
> >> >> player
> >> >> GST_DEBUG="*:3,v4l2src:3,v4l2:3" gst-launch-0.10 v4l2src
> >> >> device="/dev/video0" norm=255 ! video/x-raw-rgb, width=720,
> >> >> height=576, framerate=30000/1001 ! fakesink sync=false
> >> >>
> >> >> Anybody can answer me why?
> >> >> And how can I do it better ?
> >> >>
> >> >> I use vivi as base example for my driver
> >> >> --
> >> >> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> >> >> the body of a message to majordomo@xxxxxxxxxxxxxxx
> >> >> More majordomo info at http://vger.kernel.org/majordomo-info.html
> >> >
> >> >
> >> >
> >> > --
> >> > Peter
> >>
> >>
> >>
> >>
>
>
>
>
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