Re: alpha iommu fixes

Jonathan Lundell (jlundell@pobox.com)
Mon, 21 May 2001 08:47:38 -0700


At 6:17 PM +0400 2001-05-21, Ivan Kokshaysky wrote:
>On Mon, May 21, 2001 at 06:55:29AM -0700, Jonathan Lundell wrote:
>> 8 slots (and you're right, 6 is a practical upper limit, fewer for
>> 66 MHz) *per bus*. Buses can proliferate like crazy, so the slot
>> limit becomes largely irrelevant.
>
>True, but the bandwidth limit is highly relevant. That's why modern
>systems have multiple root buses, not a bridged ones.

Sure, there are systems with multiple root buses (I'm a bit fuzzy on
how well Linux handles that), and bandwidth is important, but it's
simply wrong to assume that a particular root bus will never have
more than 6 or 8 devices. There are legitimate cases (firewalls
spring to mind) where port count is driven by other considerations
than aggregate bandwidth.

-- 
/Jonathan Lundell.
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