Subject: Re: pciide performance on alpha
To: Manuel Bouyer <>
From: Matt Thomas <>
List: port-alpha
Date: 08/24/1999 09:04:35
At 07:02 AM 8/24/99 , Manuel Bouyer wrote:
>On Wed, Aug 18, 1999 at 06:31:37PM -0700, Matt Thomas wrote:
> > Well, I finally figured what PCIIDE DMA wasn't working.  The V5.1 SRM on
> > my 164SX sets the bus_master_dma basereg to an address over 0xffff.  The
> > problem is that the Cypress only looks at the bottom 16 bits.  It brokenly
> > reports the upper 16bits as what was written instead of 0.  But masking
> > off the upper 16 bits, I can get PCIIDE DMA to work.
> > 
> > But I only get 3.4MB/s (but at < 1% cpu utilization).  However using a 
> > IDE->SCSI converter connected to a ncr53c810a with the identical drive, 
> > I can get > 6MB/s.  Off a 875 I get > 7MB/s (since the 875 still negotiates
> > at 10MB/s).  Digital UNIX gets > 8MB/s off the same drive (using IDE) 
> > because it modifies the timing of the drives.
>Do you know if the latency timer is properly set ?
>If not, could you try the patch that has been posted to the list which sets it
>to a more sensible value ?

Yes, I make sure the latency timer is set.  There is a second problem.
The pciide driver says second DMA channel does not have dma support 
(even though it does from the primary channel).
Matt Thomas               Internet:
3am Software Foundry      WWW URL:
Cupertino, CA             Disclaimer: I avow all knowledge of this message