Date: Wed, 27 Aug 1997 09:37:28 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: petrilli@amber.org (Christopher Petrilli) Cc: mestery@winternet.com, peters@gil.com.au, smp@FreeBSD.ORG Subject: Re: A how does it work question. Message-ID: <199708271637.JAA05609@phaeton.artisoft.com> In-Reply-To: <Pine.BSF.3.95q.970827101440.20292B-100000@chaos.amber.org> from "Christopher Petrilli" at Aug 27, 97 10:16:41 am
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> In the end, I would think that software would be the conjstriction point > (in fact seperate memory makes it an MPP system, not an AMP/SMP system). > This is the concept behind ccNUMA, etc... > > Because of the nature of the FreeBSD kernel (and I suppose the probably > applies to Linux, but don't know), all I/O is threaded thru the #0 CPU, > and thereby it becomes a HUGE bottleneck. This is false. An interrupt may be handled by either CPU. The machine operates in Symmetric I/O or "virtual wire" mode (see the Intel Multiprocessing Specification, version 1.4). > Am I correct? This was what I was taught was the definition of a AMP > system, was that a single CPU controlled all I/O on the system, which is > why you have to go SMP to scale to X, and MPP to keep going from there. I agree with your definition of assymetry. However, in FreeBSD, each CPU is a worker, and all system tasks other than boot are simply "work to do". 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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