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As someone who lived through the first wave of supercomputers (I worked with Cray Y-MP models), it makes me very happy to see the second wave. For a while I tho
by jwr 3y ago
As someone who lived through the first wave of supercomputers (I worked with Cray Y-MP models), it makes me very happy to see the second wave. For a while I thought supercomputing was dead and we would just be connecting lots of PCs with a network and calling that "supercomputers".
I still remember how my mind was blown when I first learned that all of the memory in a Cray Y-MP was static RAM. Transistor-based flip-flops: extremely power hungry, but also very fast. Another way of looking at it is that all of its RAM was what we call "cache".
This, finally, looks like a supercomputer.
- com2kid 3y agoSRAM is so stupid fun to play with. All of a sudden you don't care so much about the inefficiencies of walking linked lists or trees. When everything is "already in cache", you can worry less about cache efficient algorithms! 1 cycle memory access latency is one of the reasons why tiny embedded MCUs can do things with a fraction of the MHZ of their larger counterparts. Now days of course it is all about tons of memory, tons of bandwidth, craptons of compute, and planning the flow of data ahead of time.
- boringuser2 3y agoOnly within a very small domain was this ever reasonable.
- jwr 3y agoBut that's why there's a "super" in "supercomputers"! Cray loaded a ton of static memory into their computers, then liquid-cooled the whole thing. Sure, the power requirements were through the roof, and you had a whole huge chiller system which you had to run and hope it doesn't fail. If it did fail, you really wanted to shut the machine down fast. From what I recall there was also an emergency propeller inside the back case of the Y-MP 2E, and yes propeller is a much better name for this thing than a "fan". It would delay the inevitable, although dumping those tens of kW of heat into your server room was not something you ever wanted to do. The whole point of all this was that you could do things that you couldn't with "normal" computers. That's why those were called "supercomputers". And I'm so glad that after a hiatus of about 30 years we're getting another wave of exceptional machines, which aren't just bigger PCs.
- Dylan16807 3y agoL3 cache is all SRAM but you can have pretty significant delays accessing it. Even the fastest memory cells will build up significant addressing delays as you increase in scale.
- creato 3y agoIf you have a “large” SRAM that can be accessed in one cycle, that just means your processor is slow and/or consumes more energy than it should.
- com2kid 3y ago> If you have a “large” SRAM that can be accessed in one cycle, that just means your processor is slow and/or consumes more energy than it should. MCUs are in this category, lots of embedded stuff, including the two areas I'm familiar with: game controllers and lower spec'd wearables. Very low power usage, CPU speed around 100mhz, so not too slow. You can do plenty with 100mhz and SRAM!
- SmoothBrain12 3y ago[dead]
- bigbillheck 3y ago> the first wave of supercomputers (I worked with Cray Y-MP models) The Y-MP came out in 1988, sixteen years after CRI was founded, which itself was several years after the CDC6600.
- Retric 3y agoThey presumably where born 20+ years before they started working professionally on the Y-MP. So they could easily have been alive or even a teen in 1964 when the CDC 6600 was released.
- jwr 3y agoI worked with the Y-MP models in the 1990s, and no I was not alive in 1964, although I'm not sure how we got there :-)