Date: Thu, 19 Apr 2001 12:36:04 -0700 From: Justin Wojdacki <justin.wojdacki.chiplogic.com@analog.com> To: freebsd-hackers@freebsd.org Subject: Re: The future of multiprocessors (was: SMP in 2.4 (fwd)) Message-ID: <3ADF3E24.74661D46@chiplogic.com> References: <20010419121051.D72816@wantadilla.lemis.com> <5.0.2.1.0.20010418190439.03633920@mail.etinc.com> <Pine.LNX.4.21.0104182313560.1685-100000@imladris.rielhome.conectiva> <20010419121051.D72816@wantadilla.lemis.com> <5.1.0.14.0.20010419111106.02d68f50@vssad.hlo.dec.com>
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Michael Adler wrote: > > A number of our larger customers care about computation/cubic foot. The > density of processors is important to them. SMP machines work well here. > > A future Alpha processor will be an SMT (symmetric multi threaded) > machine. Above the lowest levels, it will look like a multi-CPU > machine. The machine will keep multiple thread contexts live within the > CPU and will be capable of switching between these threads in a single > cycle. As it grows harder for compilers to find parallelism within a > single thread we have had to look elsewhere to keep the machine busy. > > -Michael > FWIW: The IBM Power3 CPU (AS/400 boxen) already has multiple hardware threads. IIRC, they don't exploit them largely because the compilers and OS were having a hard time figuring out how to use them. But the hardware can do it, if they so desire. I've found this to be a good general rule: If it's worth doing in computing, IBM's probably already tried it. -- ------------------------------------------------- Justin Wojdacki justin@chiplogic.com (408) 350-5032 Communications Processors Group -- Analog Devices To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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