Re: hdd & sound

Doug McNaught (doug@mcnaught.org)
13 Aug 1999 11:17:57 -0400


Roger Larsson <roger.larsson@skelleftea.mail.telia.com> writes:

> All of you that are having this problem. Could you reply to me with:
> a) type of ISA cards (as specific as possible, especially SCSI and
> sound)
> b) verify that you do not run SCSI/EIDE in non bus master mode.
> c) attach a output from vmstat 2 > vmstat.out
> (play sound, start this command, wait 5 secs, start disk activity,
> wait 5 secs, stop vmstat with ^C
>
> This was checked on Wakkos machine, and it indicated that no bus
> mastering / DMA was used.
> Note: my SB16SCSI II does not have DMA enabled by default... and
> ISA cards can not do bus mastering on their own.)
>
> [I will make a summary]

I've been meaning to post on this issue for the last week or so. I'm
seeing system lockups when playing MP3 files off an IDE CDROM. The
system configuration is as follows:

AMD K6/450
Soundcard is ISA SB AWE64
Ethernet is DEC Tulip--not sure of the exact chip.
System disk is Quantum QM39100TD-SW (ultra-2) on an Adaptec 2940U2W.
CDROM is generic ATAPI 40X. I'm not sure of the IDE chipset--the
kernel reports the following on bootup:

VP_IDE: IDE controller on PCI bus 00 dev 39
VP_IDE: not 100% native mode: will probe irqs later
ide0: BM-DMA at 0xe000-0xe007, BIOS settings: hda:DMA, hdb:DMA
ide1: BM-DMA at 0xe008-0xe00f, BIOS settings: hdc:DMA, hdd:DMA
hda: DELTA OPC-K101/ST1 F/W by OIPD, ATAPI CDROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14

AFAICS no IRQs are shared anywhere. I've checked the CMOS settings
and everything looks OK. The onboard USB is disabled.

When I play MP3's off the CDROM under 2.2.5-15 (Redhat Stock kernel) I
get a lot of skips, especially when switching virtual desktops under
X. The system works fine otherwise (I'm currently running the stock
kernel).

With later kernels (I've tried 2.2.10-ac8, 2.2.11pre4, and 2.2.11pre7)
I get the same skipping behavior, plus the system seems to lock up
completely for up to thirty seconds at a time--no mouse movement,
nothing. If I switch out of X to VC1 I often see SCSI BUS
timeouts/resets, even though the I/O for the MP3 is coming from the
IDE CDROM. The system is otherwise idle. Eventually the system hangs
completely, and I have to hit reset and fsck. If I don't play MP3's
the later kernels seem OK (though I haven't done extensive testing).

It seems strange to me that I get SCSI timeouts only when doing
semi-heavy IDE I/O. I've heard the Adaptec U2W cards are still a bit
flaky under Linux--could this be part of the problem?

I've tried various hdparm tweaks on the CDROM--DMA vs non-DMA, IRQ
unmasking, changing readahead values, and nothing seems to make a
significant difference.

I'm open to suggestions and will be happy to help debug. I'm not
going to rule out flaky hardware (I'm not sure how good the mainboard
is) but software does seem involved since the system at least stays up
under 2.2.5-15...

-Doug

-- 
Doug McNaught       doug@mcnaught.org     http://www.mcnaught.org/~doug

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