Choppy sound with azalia

[Julien Le Foll <julien.lefoll%gmail.com@localhost>]

Hello,
When i play music (in either mpd or mp3blaster),  the output is
randomly stuttering (like half-second returns) and sometimes very
choppy for a while (before returning to normal by itself). I can
reproduce a permanently choppy sound by setting hiwat=2 with audioctl.
CPU load is low (Intel Atom 330), no other particular programs are
running (only X).
I tried to play with a few audioctl and mixerctl values, without any
effect. Any help would be appreciated.
Thanks,
Julien

$ audioctl -a
name=HD-Audio
version=1.0
config=azalia0
encodings=slinear_le:16,slinear_be:16*,ulinear_le:16*,ulinear_be:16*,mulaw:8*,alaw:8*,slinear_le:32,slinear_be:32*,ulinear_le:32*,ulinear_be:32*
properties=full_duplex,independent
full_duplex=0
fullduplex=0
blocksize=8704
hiwat=7
lowat=6
monitor_gain=0
mode=
play.rate=44100
play.channels=2
play.precision=16
play.encoding=slinear_le
play.gain=126
play.balance=32
play.port=0x0
play.avail_ports=0x0
play.seek=0
play.samples=0
play.eof=0
play.pause=0
play.error=0
play.waiting=0
play.open=0
play.active=0
play.buffer_size=65536
record.rate=44100
record.channels=2
record.precision=16
record.encoding=slinear_le
record.gain=120
record.balance=32
record.port=0x0
record.avail_ports=0x0
record.seek=0
record.samples=0
record.eof=0
record.pause=0
record.error=0
record.waiting=0
record.open=0
record.active=0
record.buffer_size=65536
record.errors=0

$ mixerctl -a
inputs.dac02=126,126
inputs.dac03=126,126
inputs.dac04=126,126
record.adc08.mute=off
record.adc08=120,120
record.adc09.mute=off
record.adc09=120,120
mix.mix0b.mic.mute=off
mix.mix0b.lineout.m=off
mix.mix0b.mic=120,120
mix.mix0b.lineout=120,120
mix.mix0c.dac02.mut=off
mix.mix0c.mix0b.mut=off
mix.mix0d.dac03.mut=off
mix.mix0d.mix0b.mut=off
mix.mix0e.dac04.mut=off
mix.mix0e.mix0b.mut=off
outputs.lineout.mute=off
outputs.lineout.dir=output
outputs.lineout.boost=off
outputs.lineout.eapd=on
outputs.mic.mute=off
outputs.mic=85,85
outputs.mic.dir=input
mix.mix22.mic.mute=off
mix.mix22.lineout.m=off
mix.mix22.mix0b.mut=off
mix.mix23.mic.mute=off
mix.mix23.lineout.m=off
mix.mix23.mix0b.mut=off
outputs.master=126,126
inputs.dac=126,126
record.volume=120,120

$dmesg
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 5.0.1_PATCH (FUNTWIST330 #1: Sun Aug 30 23:49:48 CEST 2009
        julien@invader:/usr/obj/sys/arch/i386/compile/FUNTWIST330
total memory = 1791 MB
avail memory = 1755 MB
timecounter: Timecounters tick every 10.000 msec
timecounter: Timecounter "i8254" frequency 1193182 Hz quality 100
To Be Filled By O.E.M. To Be Filled By O.E.M. (To Be Filled By O.E.M.)
mainbus0 (root)
cpu0 at mainbus0 apid 0: Intel 686-class, 1600MHz, id 0x106c2
cpu1 at mainbus0 apid 2: Intel 686-class, 1600MHz, id 0x106c2
cpu2 at mainbus0 apid 1: Intel 686-class, 1600MHz, id 0x106c2
cpu3 at mainbus0 apid 3: Intel 686-class, 1600MHz, id 0x106c2
ioapic0 at mainbus0 apid 4: pa 0xfec00000, version 11, 24 pins
acpi0 at mainbus0: Intel ACPICA 20080321
acpi0: X/RSDT: OemId <061709,RSDT0951,20090617>, AslId <MSFT,00000097>
acpi0: SCI interrupting at int 9
acpi0: fixed-feature power button present
timecounter: Timecounter "ACPI-Fast" frequency 3579545 Hz quality 1000
ACPI-Fast 32-bit timer
pckbc0 at acpi0 (PS2K, PNP0303): kbd port
pckbc0: io 0x60,0x64 irq 1
pckbc1 at acpi0 (PS2M, PNP0F03): aux port
pckbc1: io 0x60,0x64 irq 12
pcppi0 at acpi0 (SPKR, PNP0800)
pcppi0: io 0x61
midi0 at pcppi0: PC speaker (CPU-intensive output)
sysbeep0 at pcppi0
npx0 at acpi0 (COPR, PNP0C04)
npx0: io 0xf0-0xff irq 13
npx0: reported by CPUID; using exception 16
hpet0 at acpi0 (HPET, PNP0103-0)
hpet0: mem 0xfed00000-0xfed00fff irq 2,8
timecounter: Timecounter "hpet0" frequency 25000000 Hz quality 2000
attimer0 at acpi0 (TMR, PNP0100): AT Timer
attimer0: io 0x40-0x43
WMI0 (pnp0c14) at acpi0 not configured
AWY (AWY0001) at acpi0 not configured
acpibut0 at acpi0 (PWRB, PNP0C0C-170): ACPI Power Button
apm0 at acpi0: Power Management spec V1.2
attimer0: attached to pcppi0
pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
pchb0 at pci0 dev 0 function 0
pchb0: vendor 0x10de product 0x0a82 (rev. 0xb1)
vendor 0x10de product 0x0a88 (RAM memory, revision 0xb1) at pci0 dev 0
function 1 not configured
pcib0 at pci0 dev 3 function 0
pcib0: vendor 0x10de product 0x0aad (rev. 0xb2)
vendor 0x10de product 0x0aa4 (RAM memory, revision 0xb1) at pci0 dev 3
function 1 not configured
vendor 0x10de product 0x0aa2 (SMBus serial bus, revision 0xb1) at pci0
dev 3 function 2 not configured
vendor 0x10de product 0x0a89 (RAM memory, revision 0xb1) at pci0 dev 3
function 3 not configured
vendor 0x10de product 0x0aa3 (Co-processor processor, revision 0xb1)
at pci0 dev 3 function 5 not configured
ohci0 at pci0 dev 4 function 0: vendor 0x10de product 0x0aa5 (rev. 0xb1)
LUB0: Picked IRQ 20 with weight 0
ohci0: interrupting at ioapic0 pin 20
ohci0: OHCI version 1.0, legacy support
usb0 at ohci0: USB revision 1.0
ehci0 at pci0 dev 4 function 1: vendor 0x10de product 0x0aa6 (rev. 0xb1)
LUB2: Picked IRQ 21 with weight 0
ehci0: interrupting at ioapic0 pin 21
ehci0: BIOS has given up ownership
ehci0: EHCI version 1.0
ehci0: companion controller, 12 ports each: ohci0
usb1 at ehci0: USB revision 2.0
ohci1 at pci0 dev 6 function 0: vendor 0x10de product 0x0aa7 (rev. 0xb1)
UB11: Picked IRQ 22 with weight 0
ohci1: interrupting at ioapic0 pin 22
ohci1: OHCI version 1.0, legacy support
usb2 at ohci1: USB revision 1.0
ehci1 at pci0 dev 6 function 1: vendor 0x10de product 0x0aa9 (rev. 0xb1)
UB12: Picked IRQ 23 with weight 0
ehci1: interrupting at ioapic0 pin 23
ehci1: BIOS refuses to give up ownership, using force
ehci1: EHCI version 1.0
ehci1: companion controller, 12 ports each: ohci1
usb3 at ehci1: USB revision 2.0
azalia0 at pci0 dev 8 function 0: Generic High Definition Audio Controller
LAZA: Picked IRQ 20 with weight 1
azalia0: interrupting at ioapic0 pin 20
azalia0: host: 0x10de/0x0ac0 (rev. 177), HDA rev. 1.0
ppb0 at pci0 dev 9 function 0: vendor 0x10de product 0x0aab (rev. 0xb1)
pci1 at ppb0 bus 1
pci1: no spaces enabled!
pciide0 at pci0 dev 11 function 0
pciide0: vendor 0x10de product 0x0ab5 (rev. 0xb1)
pciide0: bus-master DMA support present, but unused (no driver support)
pciide0: primary channel wired to native-PCI mode
LSA0: Picked IRQ 21 with weight 1
pciide0: using ioapic0 pin 21 for native-PCI interrupt
atabus0 at pciide0 channel 0
pciide0: secondary channel wired to native-PCI mode
atabus1 at pciide0 channel 1
ppb1 at pci0 dev 12 function 0: vendor 0x10de product 0x0ac4 (rev. 0xb1)
ppb1: unsupported PCI Express version
pci2 at ppb1 bus 2
pci2: no spaces enabled!
ppb2 at pci0 dev 16 function 0: vendor 0x10de product 0x0aa0 (rev. 0xb1)
pci3 at ppb2 bus 3
pci3: i/o space, memory space enabled, rd/line, wr/inv ok
vga0 at pci3 dev 0 function 0: vendor 0x10de product 0x087d (rev. 0xb1)
vga0: WARNING: ignoring 64-bit BAR @ 0x14
vga0: WARNING: ignoring 64-bit BAR @ 0x1c
wsdisplay0 at vga0 kbdmux 1: console (80x25, vt100 emulation)
wsmux1: connecting to wsdisplay0
drm at vga0 not configured
ppb3 at pci0 dev 21 function 0: vendor 0x10de product 0x0ac6 (rev. 0xb1)
ppb3: unsupported PCI Express version
pci4 at ppb3 bus 4
pci4: i/o space, memory space enabled, rd/line, wr/inv ok
re0 at pci4 dev 0 function 0: RealTek 8168B/8111B PCIe Gigabit
Ethernet (rev. 0x02)
LN3A: Picked IRQ 16 with weight 0
re0: interrupting at ioapic0 pin 16
re0: Ethernet address 00:e0:4c:68:00:83
re0: using 256 tx descriptors
rgephy0 at re0 phy 7: RTL8169S/8110S/8211 1000BASE-T media interface, rev. 2
rgephy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT,
1000baseT-FDX, auto
ppb4 at pci0 dev 22 function 0: vendor 0x10de product 0x0ac7 (rev. 0xb1)
ppb4: unsupported PCI Express version
pci5 at ppb4 bus 5
pci5: no spaces enabled!
ppb5 at pci0 dev 23 function 0: vendor 0x10de product 0x0ac7 (rev. 0xb1)
ppb5: unsupported PCI Express version
pci6 at ppb5 bus 6
pci6: no spaces enabled!
ppb6 at pci0 dev 24 function 0: vendor 0x10de product 0x0ac7 (rev. 0xb1)
ppb6: unsupported PCI Express version
pci7 at ppb6 bus 7
pci7: no spaces enabled!
isa0 at pcib0
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
azalia0: codec[0]: Realtek ALC662-GR (rev. 1.1), HDA rev. 1.0
azalia0: codec[3]: 0x10de/0x0007 (rev. 1.0), HDA rev. 1.0
audio0 at azalia0: full duplex, independent
uhub0 at usb0: vendor 0x10de OHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 6 ports with 6 removable, self powered
uhub1 at usb1: vendor 0x10de EHCI root hub, class 9/0, rev 2.00/1.00, addr 1
uhub1: 6 ports with 6 removable, self powered
uhub2 at usb2: vendor 0x10de OHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub2: 6 ports with 6 removable, self powered
uhub3 at usb3: vendor 0x10de EHCI root hub, class 9/0, rev 2.00/1.00, addr 1
uhub3: 6 ports with 6 removable, self powered
wd0 at atabus0 drive 1: <SAMSUNG HM500JI>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: 465 GB, 969021 cyl, 16 head, 63 sec, 512 bytes/sect x 976773168 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
uhidev0 at uhub2 port 1 configuration 1 interface 0
uhidev0: vendor 0x062a product 0x0000, rev 1.10/0.00, addr 2, iclass 3/1
ums0 at uhidev0: 3 buttons and Z dir.
wsmouse0 at ums0 mux 0
uhidev1 at uhub0 port 1 configuration 1 interface 0
uhidev1: NOVATEK USB Keyboard, rev 1.10/1.12, addr 2, iclass 3/1
ukbd0 at uhidev1
umass0 at uhub1 port 5 configuration 1 interface 0
umass0: Generic Mass Storage Device, rev 2.00/1.05, addr 2
umass0: using SCSI over Bulk-Only
scsibus0 at umass0: 2 targets, 1 lun per target
sd0 at scsibus0 target 0 lun 0: <Single, Flash Reader, 1.00> disk removable
sd0: drive offline
rum0 at uhub3 port 3
rum0: Ralink 802.11 bg WLAN, rev 2.00/0.01, addr 2
rum0: MAC/BBP RT2573 (rev 0x2573a), RF RT2528, address 00:18:1a:0c:64:8b
rum0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
rum0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps
24Mbps 36Mbps 48Mbps 54Mbps
pad0: outputs: 44100Hz, 16-bit, stereo
audio1 at pad0: half duplex
wskbd0 at ukbd0: console keyboard, using wsdisplay0
uhidev2 at uhub0 port 1 configuration 1 interface 1
uhidev2: NOVATEK USB Keyboard, rev 1.10/1.12, addr 2, iclass 3/0
uhidev2: 4 report ids
uhid0 at uhidev2 reportid 2: input=1, output=0, feature=0
uhid1 at uhidev2 reportid 3: input=3, output=0, feature=0
uhid2 at uhidev2 reportid 4: input=2, output=0, feature=0
sd0(umass0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
    SENSE KEY:  Not Ready
 COMMAND INFO:  11162912 (0xaa5520)
     ASC/ASCQ:  Medium Not Present

sd0(umass0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
    SENSE KEY:  Not Ready
 COMMAND INFO:  11162912 (0xaa5520)
     ASC/ASCQ:  Medium Not Present

sd0(umass0:0:0:0):  Check Condition on CDB: 0x00 00 00 00 00 00
    SENSE KEY:  Not Ready
 COMMAND INFO:  11162912 (0xaa5520)
     ASC/ASCQ:  Medium Not Present

boot device: wd0
root on wd0a dumps on wd0b
root file system type: ffs
wsdisplay0: screen 1 added (80x25, vt100 emulation)
wsdisplay0: screen 2 added (80x25, vt100 emulation)
wsdisplay0: screen 3 added (80x25, vt100 emulation)
wsdisplay0: screen 4 added (80x25, vt100 emulation)