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An M5 is a "3.1 GHz Intel Xeon® Platinum 8175M" ($0.192 for xlarge) while an M5a is an "AMD EPYC 7000 series processors with an all core turbo clock speed of 2

An M5 is a "3.1 GHz Intel Xeon® Platinum 8175M" ($0.192 for xlarge) while an M5a is an "AMD EPYC 7000 series processors with an all core turbo clock speed of 2.5 GHz" ($0.172 for xlarge) which is only about 10% cheaper. But the claimed clock is 20% lower. Different IPC or sustained clock might shift the balance a bit, but it seems unlikely that AMD wins decisively on performance/cost.

techrat 5y ago
"AMD EPYC 7000 series" is so vague as to be almost meaningless... so we need more info there. The 8175M's base clock 2.5Ghz, with a Turbo (all core) of 3.1Ghz and (one core) 3.5Ghz. > assuming the IPC is similar to Intel Using your assumption as a criteria... the Platinum 8175M should perform the same as an AMD EPYC 7763, whose base clock is also at 2.5Ghz with 3.5Ghz top Turbo speed. This is the only EPYC part that keeps nearly the exact same clocks as the Platinum at every stage. But we know the IPCs aren't equal, so I don't even know why you'd mention that when discussing your comparison when it's so fatally flawed from the start. Even using something as rudimentary as Passmark highlights the difference. 8175M Single Thread Rating on Passmark: 1903 EPYC 7763 Single Thread Rating on Passmark: 2639 So, clock for clock where the speed stages area identical, AMD wins. Going through the list of every Eypc 7000 series part I could find, the one that turbos at or near 2.5Ghz is the 7551... first gen part and only hits 2.55Ghz when it's all core turbo. EPYC 7551 Single Thread Rating: 1813. Performance difference ratio of single thread rating between EPYC 7551 vs Platinum 8175M: 0.95270625328 Cost difference ratio of EPYC 7551 vs Platinum 8175M: 0.89583333333 Looks like AMD is still the more cost effective solution here.
- CodesInChaos 5y ago
  The posts listing a concrete model mentioned the EPYC 7571 which has a single thread passmark of 1934. I believe first gen EPYC had an IPC pretty close to Intel. On the other hand, if I take the all core passmark result divided by cores (since you pay per-core), it's 26659/24 = 1110 vs 27445/32 = 857. They seem close enough that it's not possible to predict which one is better without actually benchmarking on AWS, since it'll depend on the clock rate they're able to sustain in AWS's setup. In any case, I don't see any significant cost savings potential for AMD on AWS, which was the point of my original post.
wtallis 5y ago
I think you may be comparing single-core turbo against all-core turbo speeds. ark.intel.com doesn't list the 8175M, but all the similar models have 2.1GHz all-core turbo with single-core turbo around 3.7 or 3.8 GHz. Other sources list the 8175M as having a base frequency of 2.5GHz and single-core turbo of 3.5GHz.

techrat 5y ago

"AMD EPYC 7000 series" is so vague as to be almost meaningless... so we need more info there. The 8175M's base clock 2.5Ghz, with a Turbo (all core) of 3.1Ghz and (one core) 3.5Ghz. > assuming the IPC is similar to Intel Using your assumption as a criteria... the Platinum 8175M should perform the same as an AMD EPYC 7763, whose base clock is also at 2.5Ghz with 3.5Ghz top Turbo speed. This is the only EPYC part that keeps nearly the exact same clocks as the Platinum at every stage. But we know the IPCs aren't equal, so I don't even know why you'd mention that when discussing your comparison when it's so fatally flawed from the start. Even using something as rudimentary as Passmark highlights the difference. 8175M Single Thread Rating on Passmark: 1903 EPYC 7763 Single Thread Rating on Passmark: 2639 So, clock for clock where the speed stages area identical, AMD wins. Going through the list of every Eypc 7000 series part I could find, the one that turbos at or near 2.5Ghz is the 7551... first gen part and only hits 2.55Ghz when it's all core turbo. EPYC 7551 Single Thread Rating: 1813. Performance difference ratio of single thread rating between EPYC 7551 vs Platinum 8175M: 0.95270625328 Cost difference ratio of EPYC 7551 vs Platinum 8175M: 0.89583333333 Looks like AMD is still the more cost effective solution here.

CodesInChaos 5y ago
The posts listing a concrete model mentioned the EPYC 7571 which has a single thread passmark of 1934. I believe first gen EPYC had an IPC pretty close to Intel. On the other hand, if I take the all core passmark result divided by cores (since you pay per-core), it's 26659/24 = 1110 vs 27445/32 = 857. They seem close enough that it's not possible to predict which one is better without actually benchmarking on AWS, since it'll depend on the clock rate they're able to sustain in AWS's setup. In any case, I don't see any significant cost savings potential for AMD on AWS, which was the point of my original post.

wtallis 5y ago

I think you may be comparing single-core turbo against all-core turbo speeds. ark.intel.com doesn't list the 8175M, but all the similar models have 2.1GHz all-core turbo with single-core turbo around 3.7 or 3.8 GHz. Other sources list the 8175M as having a base frequency of 2.5GHz and single-core turbo of 3.5GHz.