On Sun, Feb 20, 2000 at 01:48:49PM +1100, Patryk Zadarnowski wrote:
> > It looks like the hardware has to implement GPTs and know how to
> > walk them. How can FreeBSD use them without hardware support ?
>
> No it doesn't. We've got software GPT implementations for both MIPS64 and
> Alpha, and they're both peform very well in our somewhat hostile SASOS
> conditions. I'm not sure why you think that a hardware walk is necessary:
For performance reasons and memory efficiency reasons. My understanding of
your proposal is - use VHPT as a large in memory TLB and use GPT as operating
system's primary page table.
Doesn't that involve duplication of information in memory, especially if
the hash table is big ?
> the only reason why IA-64 walks VPHT in hardware *at all* is to minimize
> the impact on the pipeline and improve ILP:
I think that's an important reason. A software only TLB miss handler
would be inferior to a VHPT based solution on IA-64, IMO.
-Arun
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