From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@mcvoy.com (Larry McVoy) Date: Fri, 29 Dec 2017 16:04:25 -0800 Subject: [TUHS] Why did PDPs become so popular? In-Reply-To: References: <20171229163832.GA17231@mcvoy.com> Message-ID: <20171230000425.GI22177@mcvoy.com> On Fri, Dec 29, 2017 at 04:54:25PM -0700, Kevin Bowling wrote: > I trust your judgement and experience WRT the Alpha. > > If you're looking for massive performance deltas, what about ECL > designs like the IBM 3090 and Cray designs in the late '80s/ early > '90s? I believe those were not a multiple but a magnitude faster than > contemporaries. For vector operations, yes. For stuff that you and I care about, running the OS, serving up data, not so much. As I recall, the supercomputers were pretty crappy on anything that wasn't a vector operation. I helped port Unix to a CDC spinoff, the ETA-10, and it was faster to cross compile stuff on a Sun 3/280 than compile it natively. I haven't run on either the 3090 or the Crays but I've got friends who did (some of whom still work at Cray) and when I was crowing about what I could do a Sun nobody told me that it was faster on a cray. If you were doing scalar floating point, especially at the larger precisions, yeah, the super computers were better. If you were doing that sort of thing as a vector, so a vector of 128 bit floats, yeah, I could imagine that could be a lot faster than a Sun. SGI did a tick/tock where it was floating point focus, then integer focus. It's possible that one of their floating point designs kept pace with the super computers, I know that they went to the super computing conference each year (I did the power wall over NFS at one). But I don't know much about floating point, never use it in my code :) --lm