Date: Sat, 19 Feb 2000 20:58:50 -0800 From: Arun Sharma <adsharma@sharmas.dhs.org> To: Patryk Zadarnowski <patrykz@ilion.eu.org> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: 64bit OS? Message-ID: <20000219205850.A24847@sharmas.dhs.org> In-Reply-To: <200002200248.NAA03808@mycenae.ilion.eu.org>; from Patryk Zadarnowski on Sun, Feb 20, 2000 at 01:48:49PM %2B1100 References: <20000219183919.C23349@sharmas.dhs.org> <200002200248.NAA03808@mycenae.ilion.eu.org>
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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 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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