Date: Wed, 27 Aug 1997 11:16:33 -0700 (PDT) From: Simon Shapiro <Shimon@i-connect.net> To: Kyle Mestery <mestery@winternet.com> Cc: smp@FreeBSD.ORG, Peter Stubbs <peters@gil.com.au>, Christopher Petrilli <petrilli@amber.org> Subject: Re: A how does it work question. Message-ID: <XFMail.970827111633.Shimon@i-Connect.Net> In-Reply-To: <Pine.GSO.3.96.970827091116.7668F-100000@tundra.winternet.com>
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Hi Kyle Mestery; On 27-Aug-97 you wrote: > > On Wed, 27 Aug 1997, Christopher Petrilli wrote: > > > Because of this, wouldn't it be appropriate to say that FreeBSD is an > > Assymetric MP, not Symmetric? Symmetric means that the kernel runs on > > each processor, and there is no "one processor" which controls > > exclusivity > > to the hardware. > > > The symmetric/assymetric refers to the hardware. This is from Curt > Schimmel's book on Cacheing and MP systems: > > "To be considered an SMP system, all of the CPUs in the system must be > connected to a single bus and share a common pool of memory and share > access to all I/O devices. Each CPU must also have equal access to the > memory and bus, and some form of bus arbitration must be considered. > The > bus arbitration is usually entirely up to the hardware." > > In other words, an assymetric-MP system would be a system where each CPU > had it's own memory, own bus, etc. Not exactly. What you describe here is loosley coupled, vs. tightly coupled. Most SMP machines, as we are used to see, are tightly coupled. Many people will associate loosely coupled with MPP (Massively parallel Processing) and tightly coupled with SMP. But I have seen hybrids before. I never heard before this bit about NT running a kernel per CPU. Sounds stupid even for M$. Their NT architect is (never mind :-) but not stupid. I know 3.51 scaled terribly but never touched 4.0. Simon
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