[mythtv] Mac OS X speed decrease between 0.15 and CVS
jm at whpress.com
Fri Oct 22 14:36:37 UTC 2004
On 22 Oct 2004, at 6:59 AM, Ben de Luca wrote:
> shark looks like an awesome tool
I used Shark extensively this weekend, and it is incredibly cool.
Shark is what allowed me to find the usleep bug with Live TV that just
got fixed in CVS.
I also found some other slowdowns; Nigel, you might want to try these
and see if your situation improves.
- Around lines 1177-1192 of tv_play.cpp, there's code to update the LCD
display. This code accounted for 15% of the frontend's time on my box
(just the time calculations for deciding whether to update the LCD took
about half of that). I commented out that section and got a
significant boost in speed. I'm really hoping that the LCD support is
made conditional soon.
- Around line 1694 of NuppelVideoPlayer.cpp, the video output thread
requests realtime priority. This seems to succeed on OS X even without
SUID root (maybe when run under an administrator account?), but I found
it might actually hurt performance. I haven't done thorough tests on
the latest version, so I can't give numbers, but it's worth a try.
With these changes, the latest patches, and some aggressive
optimization flags, I got mythfrontend down to about 65% of my G4/800
while playing 640x480 NTSC (29.97fps) video. I didn't see other
low-hanging fruit; from a discussion I sparked on the ffmpeg list,
there are some Altivec optimizations to be had, but I don't understand
that code so that's a ways off unless somebody else steps up.
> Just wondering if there is a list of OSX patches out there? that are
> yet to be commited?
There's one huge bundle of them in the queue, but the end is in sight
-- hopefully in the next few days Isaac or Donavan can get them into
CVS. If you hang tight for a little while, there should be very few
uncommitted patches to wade through.
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