Re: [parisc-linux] Hanging with kernels >= 2.4.22

[Stuart Brady <sdbrady@ntlworld.com>]

On Wed, Feb 18, 2004 at 11:29:07PM -0700, Grant Grundler wrote:
> On Wed, Feb 18, 2004 at 11:52:25PM +0000, Stuart Brady wrote:
> > I'm having problems with kernels >= 2.4.22 on a 715/100.
> 
> Stuart,
> All your symptoms point at disk IO hanging.
> Setting the default queue depth to 1 would be worth trying.
> I've forgotten the details for setting queue depth.
>  
> search parisc-linux mailing list archives "scsi queue tags".
> http://lists.parisc-linux.org/pipermail/parisc-linux/2004-January/022087.html

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?

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?

http://lists.parisc-linux.org/pipermail/parisc-linux/2002-February/015465.html
says that no tagged queue is a bad thing. Why is that?

> btw, 715/50 is NOT the same as 715/100.
> 715/100 should have "coherent" DMA and 715/50 does not.
> 
> 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?
-- 
Stuart Brady