Re: [ANNOUNCE] Videobuf improvements to allow its usage with USB drivers

[Mauro Carvalho Chehab <mchehab@infradead.org>]

On Sun, 13 Apr 2008 23:38:24 +0200 (CEST)
Markus Rechberger <mrechberger@empiatech.com> wrote:

> 
> --- Mauro Carvalho Chehab <mchehab@infradead.org>
> schrieb:
> 
> > > my eeePC shows up 0-5% CPU usage with mplayer
> > > fullscreen without videobuf, seems more like
> > > something's broken in your testapplication or
> > > somewhere else?
> > 
> > The test application (capture_example) is the one
> > documented at the V4L2 spec.
> > The only difference is that I've incremented count
> > to 1000, to get more frames.
> > I don't see what's wrong on it.
> > 
> 
> I just tested capture_example on the eeePC (again non
> videobuf).
> 
> $ time ./capture_example
> .................. (printed this around 100 times?)
> real   0m4.312s
> user   0m0.010s
> sys    0m0.000s
> 
> strace clearly shows up VIDIOC_QBUF, VIDIOC_DQBUF.
> 
> So the question is rather what makes the results so
> bad on your system. 
> How can the userspace application go up to 100%, while
> the system isn't that busy?

Are you running your tests against the in-kernel version? Also, you're running
with count = 100 (the 100 dots). You need to edit the example code, and move to
1000 to have the same basement as I used here.

Cheers,
Mauro

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