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Date:      Wed, 12 Sep 2001 18:09:15 +0200 (CEST)
From:      bartscgr@t-online.de (Guenter Bartsch)
To:        Jason Andresen <jandrese@mitre.org>
Cc:        <bartscgr@studbox.uni-stuttgart.de>, Heiko Schaefer <hschaefer@fto.de>, <multimedia@freebsd.org>, xine-user <xine-user@lists.sourceforge.net>, <freebsd-hackers@freebsd.org>
Subject:   Re: [xine-user] xine on freebsd?
Message-ID:  <Pine.LNX.4.33.0109121758100.24569-100000@goofy.disney.gb>
In-Reply-To: <3B9F7CE8.E96D1B0@mitre.org>

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Hi Jason,

On Wed, 12 Sep 2001, Jason Andresen wrote:

> > even when using XvShm to display the video data xfree86 uses significantly
> > more cpu power on freebsd than on linux (~15% on freebsd compared to ~1-3%
> > on linux) which further indicates there's something wrong here.
> >
> > Comments, hints, ideas very welcome,
>

> Are you using XFree 4.x?

yep, xfree 4.1 exactly

> What video cards are in both boxes?

in my box it's a riva TNT (so I don't have Xv on FreeBSD), but in Heiko's
box (where we do most of the performance testing) we've seen these results
both with a GeForce 2MX and a Matrox G400 on a GNU/Linux / FreeBSD dual
boot machine (first there we used the GeForce card and later replaced it
by the G400 one but the results were roughly the same).

> Sometimes I wonder if Linux puts more of a buffer on DVDs than FreeBSD
> does

yep, on linux there's hardly any difference between reading single block
or larger chunks of data from the device, even when using raw devices.

FreeBSD seems to have trouble reading single blocks here, but with xine's
new dvd read_cache that heiko mentioned xine reads data in 16kb chunks and
the device read performance is roughly the same as on linux now.

The only thing that is still significantly slower on freebsd is the actual
frame display on X11. For full-PAL (720x576) images xine easily decodes
all frames on heiko's box but throws away 30% of them because X11 is too
slow to display them in time - this indicates to me that there's something
wrong with X11 shared memory support on FreeBSD here. Somehow I get the
feeling that there are extra memcpys involved here - maybe the MTRR isn't
set up correctly so the CPU caches the display data or, more likely, the
CPU is used to copy to images into the framebuffer instead of letting the
graphic's card do the work via dma/agp.

Any ideas?

Cheers,

   Guenter

--
time is a funny concept


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