Subject: Re: [linux-audio-dev] Re: more bad low latency results
From: Tim Goetze (tim_AT_quitte.de)
Date: Wed Nov 14 2001 - 16:31:51 EET
>I did not get any reaction on one of my previous mails, so I send it
>again. There have been numerous reports on this list about good LL,
>and now I find it very frustrating I can not get it myself. Please
>help me out! I'd really hate the get the impression that the whole
>LL issue is still unreal.
i'm not running any latency test programs, but the scheduling and alsa
driver latency on this system (k6-III-450, audiophile 24/96, dma-ide)
is low enough to allow me to do stereo software audio-through (read
samples from pcm capture, write them to pcm playback) with an audio cycle
time of 64 frames at 48 kHz. this means the pcm poll loop cycles reliably
at about 750 Hz (~1.3 ms between cycles).
kernels supporting this for me are 2.4.5-ll, 2.4.13-pe, 2.4.13-ll - all
of these compiled for k6 - and currently 2.4.13-ll compiled for a 386. if
there are differences between mmx and not, they are too small to be
noticeable.
there are some stress situations that can cause xruns at 64 frames/cycle
with the current kernel, for example when cron.daily runs updatedb(1) or
find(1), but since these situations are predictable and avoidable i get
along. of course that's not to say i wouldn't like to run even less
frames/cycle with absolute stability - we're just not yet there it seems.
tim
This archive was generated by hypermail 2b28 : Wed Nov 14 2001 - 16:27:42 EET