[6204] in linux-scsi channel archive
Re: Probably a silly problem ..
daemon@ATHENA.MIT.EDU (Monty)
Mon Mar 29 15:25:02 1999
From: Monty <xiphmont@mit.edu>
To: dstein2203@t-online.de (Dietmar Stein)
Cc: linux-scsi@vger.rutgers.edu
In-reply-to: Your message of "Mon, 29 Mar 1999 21:30:04 +0200."
<36FFD4BC.13A9875F@t-online.de>
Date: Mon, 29 Mar 1999 15:16:12 EST
>> Warning: Running low on SCSI DMA buffersWarning: Running low on SCSI DMA
>> buffersWarning: Running low on SCSI DMA buffers
>> etc etc, hundreds of times over.
>
>Hm, it seems that the buffer is running low which might end in a write-error
>(buffer underrun)... You are using the aha154x; I think there is an option in
>the BIOS of the controller to choose the DMA-channel... (on 1542 there is).
>Make sure that the channel (I think default is DMA 6) is not in use by
>another device which has direct memory access (soundcard and so on).
I believe this has nothing to do with the DMA channel. If I recall
Doug Gilbert's DMA/memory rants properly, ISA SCSI cards have to do
DMA under the 16MB level, and Linux 2.2 memory management is so
aggressive about managing higher memory, that it leaves almost no
space under 16M for ISA DMA. His quote is "the more RAM you have, the
less space you have under 16M" or something exactly to that effect.
Downgrade to 2.0, invest in a PCI SCSI adapter, or convince the VM
tuning folks that they did a Bad Thing (tm)....
Monty
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