[pulseaudio-discuss] Why tsched disabled when I use module-alsa-sink with 'mmap=0 tsched=1' parameters?
tanu.kaskinen at linux.intel.com
Fri Dec 19 05:55:37 PST 2014
On Fri, 2014-12-19 at 18:36 +0500, Alexander E. Patrakov wrote:
> 19.12.2014 18:15, Tanu Kaskinen wrote:
> > On Thu, 2014-12-11 at 21:49 +0900, 김정연 wrote:
> >> Dear developers,
> >> I have question something about selecting logic between timer-based
> >> and IRQ scheduling.
> >> When I tried to load 'module-alsa-sink' with 'mmap=0 tsched=1'
> >> parameters, tsched(timer-based scheduling) becomes disabled by below
> >> codes.
> >> It seems tsched is allowed only mmap supported ALSA devices. Why
> >> tsched disabled while use non-mmap driven ALSA?
> > Because rewinding is not available in non-mmap mode. That is, it's not
> > possible to rewrite previously written data in non-mmap mode. In
> > timer-based scheduling mode PulseAudio uses bigger buffer size, which
> > causes problems if rewinding isn't available.
> Sorry, rewinding is actually available in non-mmap mode. And, pulseaudio
> can rewind even without tsched (i.e., tsched == 0 does not imply
> max_rewind == 0). So the reasoning must be different. But I don't know
> the answer.
Thanks for the correction. I don't have an alternative theory either.
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