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I'd be curious to see AES encryption performance compared between the same CPUs from Ampere, Intel, and AMD. In my experience, Intel have a significant perform

by bradfa 6y ago

I'd be curious to see AES encryption performance compared between the same CPUs from Ampere, Intel, and AMD. In my experience, Intel have a significant performance advantage with their AES-NI implementation over AMD. I wonder what Ampere's cores can do. For some workloads, special things like AES-NI or other optimizations which only Intel (or another vendor) have can make a huge difference in real world performance which generalized benchmarks don't cover.

dragontamer 6y ago
> I'd be curious to see AES encryption performance compared between the same CPUs from Ampere, Intel, and AMD. In my experience, Intel have a significant performance advantage with their AES-NI implementation over AMD. I wonder what Ampere's cores can do. AMD in Zen1 had 2x AES-pipelines, allowing 2x 128-bit AES operations per clocktick. Intel caught up later, and eventually also added 2x AES-pipelines of their own. But then AMD added 256-bit AES instructions to Zen3 (which are 128-bit x2 vectorized). AVX512 does have 4x SIMD AES on AVX512 (4x128 bit wide), for 4x parallel AES computations per clock tick. But that's not on consumer chips. I guess that's the widest AES implementation right now however, but AMD isn't that far behind in Zen3. -------- If anything, I'd say AMD actually was beating Intel at the AES-benchmark at Zen1 (In year ~2017 or so), but Intel / AMD have been trading blows with each other since then.
- bradfa 6y ago
  I haven't been able to test any Zen 3 CPUs. Now I'm curious! From benchmarks listed here: https://calomel.org/aesni_ssl_performance.html https://calomel.org/aesni_ssl_performance.html it seems that Intel had similar performance in their 2015 release of the i7-6700 as AMD's 2017 release of Ryzen 7 1800X. Raw general purpose benchmarks I found via Google put the Ryzen 7 1800X at about twice the compute capability as an i7-6700, but their AES performance is quite even.
  - dragontamer 6y ago
    CBC mode cannot be parallelized. That is a sequential-only algorithm, and none of the stuff I talked about before can take advantage of CBC mode. GCM mode can be parallelized. Notice AES-128-GCM (which can take advantage of 2x pipelines) really flies on Zen1 compared to 6700.
    - bradfa 6y ago
      Regardless, it does really all come down to what your compute need is, and specialized metrics for somewhat odd-ball cases can sometimes still heavily favor Intel for the money. Thanks for your comments! I didn't previously fully comprehend how the AVX modes and pipeline widths mattered for AES.
      - dragontamer 6y ago
        Yeah, this is super-specialized. I just happen to have studied the AES instructions to a ridiculous degree a few years ago... (https://github.com/dragontamer/AESRand https://github.com/dragontamer/AESRand) You don't come up with 32-bytes of random numbers every 4-clock ticks unless you understand this stuff. :-)

by bradfa 6y ago

dragontamer 6y ago

> I'd be curious to see AES encryption performance compared between the same CPUs from Ampere, Intel, and AMD. In my experience, Intel have a significant performance advantage with their AES-NI implementation over AMD. I wonder what Ampere's cores can do. AMD in Zen1 had 2x AES-pipelines, allowing 2x 128-bit AES operations per clocktick. Intel caught up later, and eventually also added 2x AES-pipelines of their own. But then AMD added 256-bit AES instructions to Zen3 (which are 128-bit x2 vectorized). AVX512 does have 4x SIMD AES on AVX512 (4x128 bit wide), for 4x parallel AES computations per clock tick. But that's not on consumer chips. I guess that's the widest AES implementation right now however, but AMD isn't that far behind in Zen3. -------- If anything, I'd say AMD actually was beating Intel at the AES-benchmark at Zen1 (In year ~2017 or so), but Intel / AMD have been trading blows with each other since then.

bradfa 6y ago
I haven't been able to test any Zen 3 CPUs. Now I'm curious! From benchmarks listed here: https://calomel.org/aesni_ssl_performance.html https://calomel.org/aesni_ssl_performance.html it seems that Intel had similar performance in their 2015 release of the i7-6700 as AMD's 2017 release of Ryzen 7 1800X. Raw general purpose benchmarks I found via Google put the Ryzen 7 1800X at about twice the compute capability as an i7-6700, but their AES performance is quite even.
- dragontamer 6y ago
  CBC mode cannot be parallelized. That is a sequential-only algorithm, and none of the stuff I talked about before can take advantage of CBC mode. GCM mode can be parallelized. Notice AES-128-GCM (which can take advantage of 2x pipelines) really flies on Zen1 compared to 6700.
  - bradfa 6y ago
    Regardless, it does really all come down to what your compute need is, and specialized metrics for somewhat odd-ball cases can sometimes still heavily favor Intel for the money. Thanks for your comments! I didn't previously fully comprehend how the AVX modes and pipeline widths mattered for AES.
    - dragontamer 6y ago
      Yeah, this is super-specialized. I just happen to have studied the AES instructions to a ridiculous degree a few years ago... (https://github.com/dragontamer/AESRand https://github.com/dragontamer/AESRand) You don't come up with 32-bytes of random numbers every 4-clock ticks unless you understand this stuff. :-)