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Old 2021-08-07, 00:03   #45
ewmayer
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Quote:
Originally Posted by frmky View Post
One node with 2 x Cavium ThunderX2 CN9980 32-core 64-bit ARM cpus and DDR4 memory.

VBITS = 64 2h 57m
VBITS = 128 2h 1m
VBITS = 256 2h 2m
By VBITS do you mean #threads running on the CPU? (The 9980 is like the Intel KNL, in supporting up to 4 threads per core).

Just curious, how much might such a beast cost? (Need not be new.) The bare CPUs can be had for reasonably low cost, but what kind of motherboard are we talking? Looks like it uses standard server-type DDR4 RAM, at least.
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Old 2021-08-07, 02:20   #46
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No, VBITS is the number of bits in each vector entry used in the block Lanczos iteration. It's adjustable at compile time to be 64, 128, or 256 (or 512 in my hosted version). In the code, it's implemented as a struct of 1, 2, or 4 (or 8) uint64's. Using "wider" vectors does more work per iteration but requires fewer iterations. x86_64 cpus typically work well with either VBITS of 64 or 128 with little difference in runtime. ARM and nVidia GPU architectures typically work better with 128 or 256.

The Cavium systems are usually enterprise servers and are priced as such. I'm not aware of anyone using them in workstations or consumer-grade hardware. I'm not sure how much they might go for in the used market.
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Old 2021-08-08, 00:05   #47
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Quote:
Originally Posted by frmky View Post
The Cavium systems are usually enterprise servers and are priced as such. I'm not aware of anyone using them in workstations or consumer-grade hardware. I'm not sure how much they might go for in the used market.
Quickly found this from early 2018:

Cavium's ThunderX2 processor powers first 64-bit ARMv8 workstation | ZDNet

Another from the same timeframe on Anandtech:

https://www.anandtech.com/show/12571...thunderx2-socs

Nothing about pricing in either - Anandtech says "GIGABYTE does not publish pricing of the ThunderXStation, but we have reached out to PhoenicsElectronics and will update the story once we get more information on the matter", but article shows no such updates. But cool to know such gear is a thing - ~4 years ago when they were new, KNL workstations sold new for $5000, now you can get them cheaply in the used/refurb market.
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