[snd_hda] Choppiness under high cpu - STABLE

Norberto Meijome freebsd at meijome.net
Mon Jun 4 04:06:37 UTC 2007

On Tue, 29 May 2007 16:39:49 +1000
Norberto Meijome <freebsd at meijome.net> wrote:

> > 
> > Anyway, you can try adjusting buffer size
> > with "hint.pcm.0.buffersize" . Start with 4096, 8192, 16384, etc.. Use
> > either kenv(8) and reload, or slap it into /boot/device.hints and
> > reboot.  
> Thanks, I'll have a play and inform back :)

ok, so I've had some time to test (apologies for the delay)

updated my kernel to latest -STABLE :
FreeBSD ayiin.octantis.com.au 6.2-STABLE FreeBSD 6.2-STABLE #4: Mon Jun  4 12:45:01 EST 2007     root at ayiin.octantis.com.au:/usr/obj/usr/src/sys/AYIIN  i386

(EST == AU EST, GMT +10)

I am testing with snd_hda in this tree. World was built from sources of May 30th.

no kernel hints tweaking.
( not sure if this is related, but sysctl shows:

hw.snd.pcm0.buffersize: 16384

 installed sysutils/stress to have a somewhat more reliable method of test, rather than buildworld. It seems the issue is not necessarily high user CPU usage, but system cpu usage , which is triggered by stress' -m switch (more specifically, virtual memory stress testing). I tested with xmms-esound, esd running from my X session, playing a (Smashing Pumkins :D) CD on my CD drive.

Presents problem.
[betom at ayiin] [Mon Jun  4 13:39:59 2007]
$ stress -m 1 -c 1
stress: info: [8731] dispatching hogs: 1 cpu, 0 io, 1 vm, 0 hdd

No Problems at all:
[betom at ayiin] [Mon Jun  4 13:40:15 2007]
$ stress -c 1
stress: info: [8735] dispatching hogs: 1 cpu, 0 io, 0 vm, 0 hdd

Problems again.
[betom at ayiin] [Mon Jun  4 13:40:26 2007]
$ stress -m 1
stress: info: [8738] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd

Changing buffersize makes no difference at all (tried up to 24K).

when I loaded the binary blob provided in your site, I can run up to stress -m 3 with no problems at all. -m 4 shows some issues if i start heavily using the system. -m 5 is somewhat similar to -m 1 with the non-low-latency driver.

Please let me know  if there's anything else u'd like me to try.


{Beto|Norberto|Numard} Meijome

"At times, to be silent is to lie." 
  Miguel de Unamuno

I speak for myself, not my employer. Contents may be hot. Slippery when wet. Reading disclaimers makes you go blind. Writing them is worse. You have been Warned.

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