
Marvell Announces ThunderX3: 96 Cores, 384 Thread 3rd Gen Arm Server Processor - rbanffy
https://www.anandtech.com/show/15621/marvell-announces-thunderx3-96-cores-384-thread-3rd-gen-arm-server-processor
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rajnathani
It’s nice to see the use of 4-way SMT on Arm in the server space. The recent
news of Ampere Computing (headed by Intel’s former president) launching their
80 core data-center focused Arm processor was great too, however both their
processor and AWS’s Arm based Graviton processor attempt to seemingly keep
things more power efficient and/or “secure” [0] by doing away with hyper-
threading. While it can be argued that the security model is better without
SMT as Intel’s vulnerabilities from recent years show, I have a slight hunch
(Disclaimer: I have no expertise in chip design whatsoever!) that given the
out-of-order execution [1] of instructions in all modern processors that there
is potentially a fair bit of unused instructions capacity in each clock cycle
without SMT, even for server workloads.

[0] [https://www.eetimes.com/startup-ampere-attacks-intels-
streng...](https://www.eetimes.com/startup-ampere-attacks-intels-strength/)

[1] [https://en.m.wikipedia.org/wiki/Out-of-
order_execution](https://en.m.wikipedia.org/wiki/Out-of-order_execution)

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rbanffy
The OS can always mitigate that by avoiding running threads with different
security contexts on the same core.

