From mboxrd@z Thu Jan 1 00:00:00 1970 From: kevin.bowling@kev009.com (Kevin Bowling) Date: Fri, 29 Dec 2017 16:54:25 -0700 Subject: [TUHS] Why did PDPs become so popular? In-Reply-To: <20171229163832.GA17231@mcvoy.com> References: <20171229163832.GA17231@mcvoy.com> Message-ID: 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. Regards, On Fri, Dec 29, 2017 at 9:38 AM, Larry McVoy wrote: > On Fri, Dec 29, 2017 at 04:04:01AM -0700, Kevin Bowling wrote: >> Alpha generally maintained integer/ALU and clockspeed leadership for >> most of the '90s >> http://www.cs.columbia.edu/~sedwards/classes/2012/3827-spring/advanced-arch-2011.pdf > > Wow, that first graph is the most misleading graph on CPU performance > I've ever seen. Ever. > > So from 1993 to 2000 the only CPUs released were Alphas? > > That era was when I was busy measuring performance across cpus and > operating systems and I don't ever remember any processor being a > factor of 2 better than its peers. And maybe I missed it, I only > owned a couple of alpha systems, but I never saw an Alpha that was > a game changer. Alpha was cool but it was too little, too late to > save DEC. > > In that time period, even more so now, you had to be 2x better to get > a customer to switch to your platform. > > 2x cheaper > 2x faster > 2x more reliable > > Do one of those and people would consider switching platforms. Less than > that was really tough and it was always, so far as I remember, less than > that. SMP might be an exception but we went through that whole learning > process of "well, we advertised symmetric but when we said that what we > really meant was you should lock your processes down to a processor > because caches turn out to matter". So in theory, N processors were N > times faster than 1 but in practice not so much. > > I was very involved in performance work and cpu architecture and I'd love > to be able to claim that we had a 2x faster CPU than someone else but we > didn't, not at Sun and not at SGI. > > It sort of make sense that there weren't huge gaps, everyone was more or > less using the same sized transistors, the same dram, the same caches. > There were variations, Intel had/has the biggest and most advanced > foundries but IBM would push the state of the art, etc. But I don't > remember anyone ever coming out with a chip that was 2x faster. I > suspect you can find one where chip A is introduced at the end of chip > B's lifespan and A == 2*B but wait a few month's and B gets replaced > and A == .9*C. > > Can anyone point to a 2x faster than it's current peers chip introduction? > Am I just not remembering one or is that not a thing? > > --lm