[mythtv] Choppy performance on Mac Intel builds / scaling issue?

usleepless at gmail.com usleepless at gmail.com
Sun Mar 26 21:52:01 UTC 2006


well to be complety honest i am asking this for the following reason:
i have been porting mythtv to freebsd and have stumbled upon issues
regarding the use of usleep in mythtv.

i started out with 4.11 and ended up on 6.0, which helped, but i still
believe that the usleep-syncronizing is not very crossplatform nor
efficient.

apparently, there are a lot of usleeps going on in your case ( this is
what was suggested as the reason for the high 
ml_set_interrupts_enabled rate anyway ). you might want to redefine
usleep to include a print of the file and line from where it was
executed, it might give you a clue. i could provide a snippet if you
would like to.

my theory is that the usleeps are are keeping the scheduler busy,
while other processes should be given cpu to do the work. lots of
context switches.

otoh, this could just be a rant, since other people are claiming suc6
on the same hardware.

i am running a mythtv-0.18.2 build with a lot of patches to disable
the use of usleeps and replace them by qwaitconditions. my experience
with these changes are: mythtv is more responsive, the rest of the
machine is more responsive ( dual head with mythtv in a window ). i am
running this on fbsd 6 and a xbox running xebian.

regards,

usleep

On 3/26/06, matt mead <m-mythtv at goof.com> wrote:
> I am not seeing the behavior that you describe on my mini duo core with
> an MMX enabled build, however, I do see something that sounds similar on
> my athlon 64 backend/frontend.  It enters this cyclical behavior where
> it plays a handful of frames normally, then stutters, then normal, etc.
>   If I pause for 2-3s and unpause, it almost always goes away.  Can you
> try this and see what it does for you?
>
>
>
> -matt
>
> James Mitchell wrote:
> > On Sun, Mar 26, 2006 at 12:49:51PM -0800, Todd Ignasiak wrote:
> >> On 3/26/06, James Mitchell <mitchell at bruteforce.org> wrote:
> >>> In contrast to some other reports of good 1080i performance
> >>> via the MMX enabled builds of 0.19, I'm experiencing issues
> >>> with both 1080i content, and scaled 480i content.
> >> When you say 'choppy' what do you mean?   Does it momentarily pause
> >> completely, or just have motion that's not smooth?
> >
> > It appears to be dropping a lot of frames. Just based on a visual
> > estimate, I'd say I'm getting maybe 10 fps. The behavior also seems
> > sort of 'bursty' with some number of decent frames, slowdown,
> > some number of decent frames, slowdown, etc.
> >
> > I ran 'mythfrontend -v all' and quite a few of these:
> >
> > 2006-03-26 15:02:05.073 NVP: Audio is 3.3871 frames ahead of video,
> > doubling video frame interval.
> >
> > 2006-03-26 15:02:05.722 NVP: Video is 5.03039 frames ahead of audio,
> > dropping frame.
> >
> > I'm not sure what 'normal' is, though.
> >
> >> When looking at my performance in Shark, YUV422_UC_ToRGB32BitColorBGRA
> >> is not even listed.   I'm not sure when / why that comes into play.
> >
> > What's your display resolution, and what sort of content are you playing
> > when you _don't_ see the YUV422_UC_ToRGB32BitColorBGRA function?
> >
> > James
> > _______________________________________________
> > mythtv-dev mailing list
> > mythtv-dev at mythtv.org
> > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
>
> --
> matt mead
>
> http://www.goof.com/
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