Date: Fri, 18 Feb 2000 16:06:55 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Arun Sharma <adsharma@sharmas.dhs.org> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: 64bit OS? Message-ID: <200002190006.QAA82061@apollo.backplane.com> References: <20000218150219.A17763@sharmas.dhs.org>
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:and Linux essentially treats hardware page tables as TLBs.
:
:The problem with the above approach is duplication of information between
:Linux page tables and hardware page tables and inefficient use of memory
:for page tables.
:
:I think OSes like FreeBSD which don't have a concept of machine independent
:page table are essentially free to do anything in the hat layer and thus
:have more flexibility.
If I understand the hardware hash table method correctly, then
I think the absolute best choice for FreeBSD is to use that method
as it will allow us to get rid of the scaleability problems we have
with the pv_entry_t scheme we use for IA32. The number of pv_entry_t's
in an IA64 architecture wind up being fixed. How big can we make the
hardware-assisted hash table?
Also, a hash table scheme is a much better fit for a 64 bit address
space model, especially with sparse mappings. The MIPS R4K and later
all use a hash table scheme and it seems to work well for them.
:I'd love to have technical discussions about the IA-64 architecture
:from an OS perspective, if anyone on this list is interested.
:
:Since last September, I've moved on to a new daytime job, which has
:nothing to do with operating systems or kernels. I have a limited amount
:of spare time and I'm willing to help out with a IA-64 port, if the
:FreeBSD project decides to pursue it.
:
: -Arun
:
-Matt
Matthew Dillon
<dillon@backplane.com>
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