Date: Sat, 23 Dec 1995 00:40:17 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: gclarkii@FreeBSD.ORG Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: SMP Motherboards Message-ID: <199512230740.AAA21670@phaeton.artisoft.com> In-Reply-To: <199512222121.PAA18590@main.gbdata.com> from "Gary Clark II" at Dec 22, 95 03:21:09 pm
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> Does anyone here have an idea on what would be the cheapest SMP compatible > motherboard? This board will only be for hacking on so a 486 based system > would be just fine (I have axp 4 486DX-33 here). ISA and VLB is also fine. Jack Vogel, who made patches to the 28 Oct 94 tree for SMP, has an ASUS dual P90 EISA/PCI. I've got an ASUS dual P90 ISA/PCI (my only intent was to hack SMP stuff, so I went budgo -- total system cost without monitor was in the $1990 range). If you do a 486, you should be aware that the SMP patches that Jack Vogel passed around definitely assume Pentiums. Further, theyy assum internal APIC's. Finally, they assume a BIOS memory area and an ID that is not the ID in the spec. So if you go hacking, be aware that the patches you can get your hands on right now are far from general. There is a nice problem between L1 cache proficiency and scheduling anonymity in the current code, since there is no way for a process to express a processor preference. This is both good and bad, since it trades extreme scheduler complexity for basically a stack hack and the lieklihood of increased overhead on process rescheduling, especially when a preeemption occurs because of a quantum expiration rather than a blocking event. If you are planning on hacking locore.s and mpcore.s code, then a 486 might be OK. Otherwise, you'll want to go for a P90, and then most likely an ASUS. Finally, if you want to run right now without some agregious hacks, you will need to sup a CVS tree and check out the code from 28 Oct 94 and apply Jack's patches, plus the mpasm.h that Jack forgot initially, and the small ordering hacks for the binary code #included in the mpcore.s file (it is generated from post-assembly of "mpboot"). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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