snd_ich skipping playback

[Roland Smith]

On Tue, Nov 20, 2007 at 06:50:05PM +0100, Frank Staals wrote:
> I updated to RELENG_7 yesterday, but I'm noticing that the snd_ich driver 
> quite often skips playback for a short period of time at some points. 
> Especially when doing mysql queries. Anyone else having problems with 
> snd_ich ?
> 
> frank at FStaals$ uname -a
> FreeBSD FStaals.net 7.0-BETA3 FreeBSD 7.0-BETA3 #2: Mon Nov 19 19:50:46 CET 
> 2007     root at FStaals.net:/usr/obj/usr/src/sys/PFSERVERKERNEL  amd64
> 
> frank at FStaals$ pciconf -lv
> pcm0 at pci0:0:4:0:        class=0x040100 card=0x71851462 chip=0x005910de 
> rev=0xa2 hdr=0x00
>    vendor     = 'Nvidia Corp'
>    device     = 'Realtek ALC850 Realtek AC'97 Audio'
>    class      = multimedia
>    subclass   = audio
> 
> frank at FStaals$ dmesg | grep pcm
> pcm0: <nVidia nForce4> port 0xea00-0xeaff,0xee00-0xeeff mem 
> 0xfe02d000-0xfe02dfff irq 23 at device 4.0 on pci0
> pcm0: [ITHREAD]
> pcm0: <Avance Logic ALC850 AC97 Codec>

I've had trouble with skipping sound some time ago on machines with
another chipset;
$ cat /dev/sndstat 
FreeBSD Audio Driver (newpcm: 64bit 2007061600/amd64)
Installed devices:
pcm0: <VIA VT8237> at io 0xd800 irq 22  [MPSAFE] (5p:4v/1r:1v channels 
duplex default)

I put the following in /boot/device.hints

# Larger DMA buffer for the soundcard, for better sound quality.
hint.pcm.0.buffersize="16384"

This fixed the problem for me.

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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