[pulseaudio-discuss] [PATCH] Do not use tsched watermark if tsched is disabled

pl bossart bossart.nospam at gmail.com
Tue Sep 7 17:52:18 PDT 2010

>> So what does this test mean? pavucontrol obviously affects the latency
>> of the sink due to it's VI meters. This obviously increases the
>> likelihood of a rewind being triggered.So, with this in mind what
>> values do you suggest we pick?
> Pierre, is it your understanding that it is when DMA transfer collides with
> cpu->RAM transfer that makes the DMA stream to become broken permanently? Or
> exactly what is it that makes it break?

The low-latency setting has nothing to do with rewinds. It's when you
actually change the volume that you will rewind and remix with the new
stream volume. You could set a super low latency and rewind exactly
once when the stream starts.

There are two issues with the rewind. One is a race condition between
the DMA and the ring buffer update. If you rewind and update the ring
buffer, the DMA may actually have already fetched older data. The
second is that you could experience underflows if you don't do the
update fast enough. By enabling logs you should be able to find out if
there are real underflows.

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