[MPlayer-dev-eng] Re: Make -nortc the default?

Uoti Urpala uoti.urpala at pp1.inet.fi
Sat Sep 9 00:01:07 CEST 2006


On Fri, 2006-09-08 at 18:12 +0000, Carl Eugen Hoyos wrote:
> - -nortc typically saves 10% CPU time on playback.
>   That often makes the difference when trying to play HD content (or just H264).
>   (That's on an AMD 2600+ running SuSE 10.0, 2.6.13)

MPlayer becoming that much faster when running alone sounds surprising.
Can anyone else confirm this? I would have expected the biggest negative
effect to be on other programs; if the kernel considers MPlayer an
interactive process and wakes it up whenever the rtc fd becomes readable
that can cause 2000 context switches per second when MPlayer is sleeping
in the rtc timer loop. OTOH if MPlayer is already using most of the CPU
then it won't spend that much time in the timer loop, and I wonder where
exactly the extra CPU usage comes from then. If the video is already
falling behind then MPlayer won't sleep and the rtc timer isn't accessed
at all, so overhead should only come from the kernel writing to the fd.

Anyway since no one gave arguments for keeping rtc as the default I'll
change it to default off. What documentation changes should there be?
Man page should list -rtc instead of -nortc, anything else? Should there
be a specific mention of the change for people who might have a reason
to keep using rtc?




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