[alsa-devel] multi pcm and mmap problem

John Rigg aldev at sound-man.co.uk
Sun Dec 2 14:40:11 CET 2007

On Sat, Dec 01, 2007 at 06:33:35PM -0500, Tim wrote:
> Takashi, after a week of testing your multi-plughw patch 
>  I'm satisfied it works fine.
> One odd thing is that when I start Jack, sometimes I 
>  immediately get a series of ever increasing xruns,
>  sometimes hundreds of them with each display update of QJackctl.
> Simply restarting QJackctl cures it and it runs for many hours 
>  without trouble.
> I am not convinced it has anything to do with your patch,
>  maybe just my new .asoundrc and new altered setup.

It's a known problem with pcm_multi and qjackctl. qjackctl reports
xruns that aren't actually happening when using pcm_multi. Some
other apps like jamin do this too. Don't worry about it unless you
hear dropouts (in which case the alsa driver will report a real xrun).


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