Next-Generation IBM POWER10 Processor

Re:Next-Generation IBM POWER10 Processor by mjb on Monday August 17, 2020 @10:31AM (#24187618)

> Newer CPUs, e.g.: AMD EPYC or any recent Intel Xeon can do about 1 GB/s/core, but I haven't seen any CPUs that significantly exceed that.

Modern processors can do ~2.1GB/s per core for AES-256-GCM (about 2x what they can do for AES-CBC).

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Re:Next-Generation IBM POWER10 Processor by dragontamer on Monday August 17, 2020 @11:21AM (#24188110)

It should be noted that AES-CBC doesn't have any instruction-level parallelism available.

Both EPYC and Xeons have 2-AES units per core now. But CBC can only effectively use one of them at a time. (Block(n+1) cannot be computed until block(n) is done computing. Because Block(n) is used as input into Block(n+1) in CBC mode).

AES-256-GCM can compute block(n) and block(n+1) simultaneously. So you need to use such a parallel algorithm if you actually want to use the 2x AES pipelines on EPYC or Xeon.

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Re:Next-Generation IBM POWER10 Processor by formerly_proven on Monday August 17, 2020 @02:15PM (#24190054)

More like ~3.9 GB/s for a desktop CPU and somewhere north of 7 GB/s for AES-256-CTR. The performance difference between CBC and CTR is pretty much exactly what you'd expect, you can only use one out of two units, and you have to wait out the full latency (1:4 disadvantage on recent cores) => ~8x slower.

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