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Subject: Re: Problem with aacraid driver in 2.5.63-bk-latest
From: Mark Haverkamp <markh@osdl.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: dougg@torque.net, Christoffer Hall-Frederiksen <hall@jiffies.dk>,
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On Wed, 2003-03-12 at 17:06, Alan Cox wrote:
> On Wed, 2003-03-12 at 23:55, Douglas Gilbert wrote:
> >          /*
> >           * Limit max queue depth on a single lun to 256 for now.  Remember,
> >           * we allocate a struct scsi_command for each of these and keep it
> >           * around forever.  Too deep of a depth just wastes memory.
> >           */
> >          if(tags > 256)
> >                  return;
> > ....
> 
> I can see the memory consideration. However the thing can really handle big
> queues well. Possibly we should be setting the queue to 512 / somefunction(volumes)
> though to avoid the worst case overcommit here
> 

Does the cmd_per_lun element of the Scsi_Host_Template structure serve
more than one purpose?  In scsi_alloc_sdev it is passed into
scsi_adjust_queue_depth.  In the aacraid case this is 512.  Later the
aacraid driver (in aac_slave_configure) sets the queue depth to either
128 for tagged or 1 if not.

Mark.
-- 
Mark Haverkamp <markh@osdl.org>

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