[snd_hda] Choppiness under high cpu - STABLE

Norberto Meijome freebsd at meijome.net
Mon Jun 4 13:08:00 UTC 2007

On Mon, 4 Jun 2007 16:44:20 +0800
Ariff Abdullah <ariff at FreeBSD.org> wrote:

> > 
> > Have you tried with 4096 ? Note: this should go into
> > hint.pcm.0.buffersize kernel hint, not sysctl variable. After
> > setting it (using kenv), you must reload the sound module or reboot
> > if it going through /boot/device.hints. The sysctl buffersize is
> > there purely as indicator.
> >   
> I forgot to mention that enabling/disabling vchans are matters as
> well, so please take note on that.

ok - back to the klds from the src tree.

[betom at ayiin] [Mon Jun  4 22:30:37 2007]
$ sysctl -a | grep snd
hw.snd.report_soft_formats: 1
hw.snd.targetirqrate: 32
hw.snd.verbose: 1
hw.snd.maxautovchans: 4
hw.snd.unit: 0
hw.snd.pcm0.buffersize: 4096
hw.snd.pcm0.vchans: 1

[betom at ayiin] [Mon Jun  4 22:30:43 2007]
$ kenv | grep buffer

I tried 4096, 8192, 16384. In all cases, stress -m 1  brings up immediate
choppiness/chirping. :(

I'm now back to the binary blob... I repeated the tests (with default
buffersize of 16K, and 8 vchans as before), and it seems that with stress -m 2
there is an ever so slight chirpiness, more noticeable with -m 3 , definitely
there @ -m 4 - but definitely better than the other one.


{Beto|Norberto|Numard} Meijome

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