Xref: utzoo comp.arch:16511 comp.os.mach:436 Path: utzoo!attcan!uunet!husc6!encore!pinocchio.encore.com From: jkenton@pinocchio.encore.com (Jeff Kenton) Newsgroups: comp.arch,comp.os.mach Subject: Re: 88k vs. i860 for a shared memory parallel processor running MACH Message-ID: <12042@encore.Encore.COM> Date: 14 Jun 90 11:41:55 GMT References: <1890@xn.LL.MIT.EDU> Sender: news@Encore.COM Followup-To: comp.arch Lines: 32 From article <1890@xn.LL.MIT.EDU>, by jjh@XN.LL.MIT.EDU (James J. Hunt): > Would anyone care to comment on the relative advantages and disadvantages of > the Motorola 88100/88200 and the Intel i860 for a shared memory > multiprocessor running MACH. I would like to hear how well each processor > is suited to MACH and memory sharing within a MACH task; and what this means > for system performance. I have my own prejudices on this matter, but I > would like to hear from people with some experience with either of these > chips and/or MACH. > You can certainly run MACH on the 88000 -- it's been/being done in several places. I don't know what the i860 provides for atomic locking of memory, which any multiprocessor implementation would use. That, and the question of flexible memory allocation in the MMUs, are the only serious requirements you would need for multi-processor MACH. Other aspects of the chips will affect the ease of the port, but not whether it's possible. For "ease", the 88000 is straightforward but RISCy. The exception handling, in particular, requires some care. An atomic XMEM instruction provides locking. Don't remember what it takes to do locking on the i860. It looks like some of the low level exception handling (especially the floating point stuff) could be amusing. The 88000 has been fun to work with (twice!). I'm sure some i860 fans will tell their side of the story. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - jeff kenton --- temporarily at jkenton@pinocchio.encore.com - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -