[parisc-linux] Hanging with kernels >= 2.4.22

[Grant Grundler]

On Sat, Feb 21, 2004 at 07:58:49AM +0000, Stuart Brady wrote:
> Thanks! Changing NCR_700_MAX_TAGS to 1 in drivers/scsi/53c700.h did the
> trick. Will I now have poor disk performance? If so, might I get away
> with setting it to something higher, like 2 or 4, maybe?

You can try, but I don't think it's worth it.

> I've not heard of tagged command queues before - the idea seems to be to
> transfer data to the drive as early as possible, but make decisions as
> to what should be written first at a later stage. Is that correct?

Sort of yes. The reasons are a bit more complicated than that.
Key reasons are better utilization of disk buffer (w/o enabling WCE)
and allow disk firmware to optimize for maximum throughput.
There are tradeoffs and caveats to both.

> > Maybe a FAQ entry for "715/xxx hangs" could be your first contribution?
> 
> That's a good idea. Where should I send the entry? Here?

Yes please. Making a diff against the file carlos pointed at
would be easiest for me. But I'll take a single paragraph
in plain text as well.

The FAQ entry should mention which machines/SCSI controllers/disks
are affected and how to set the queuedepth. Anything else is
extra credit and I reserve the right to edit it out. :^)

thanks,
grant

> -- 
> Stuart Brady
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