Date: Thu, 24 Jul 1997 13:57:17 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: lamaster@george.arc.nasa.gov Cc: freebsd-smp@FreeBSD.ORG Subject: Re: Lots 'o PCI slots Message-ID: <199707242057.NAA18060@phaeton.artisoft.com> In-Reply-To: <199707242002.NAA24606@george.arc.nasa.gov> from "lamaster@george.arc.nasa.gov" at Jul 24, 97 01:02:19 pm
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> That could be welcome news in some cases, but, since Unix/BSD folks > tend to shy away from such boards anyway whenever possible, it seems > that the only real "benefit" for well-behaved boards is going to be > increased latency. For example, the most performance-critical > path is usually the SCSI controller. If the controller already > has a minimal-interrupt message-passing flavor, does gather-scatter, > etc., what's the difference? Except for the added PCI bus traffic > and the added latency due to the I/O request having to get processed > in the I2O processor. > > What am I missing? PCI-PCI bridging, I would guess, where the i960 is a cluster communications processor more than simply a method of offloading interrupts. It would be a relatively cheap method of obtaining background distributed cache coherency processing (among other things). One might even use the i960 for the scheduler and for forcible process migration. Only a theory... 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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