[Posted in the ARM thread, asked by others to post here. Some modifications made.]
As Graviton2 has shown, it's possible for Arm to be applied to a server chip and produce results that seem somewhat competitive. Since they couldn't put Graviton2 up against Rome directly (yet), I went ahead and compared specint2006 published results, and yes, I know there are a lot of caveats. But it doesn't really look terribly competitive.
On the surface, the IPC looks great in the specint scores. So I went ahead and compared to 7742 published results.
Graviton2 is gcc9.2, 7742 is gcc8.3
Single-thread
IPC is what everyone clamors about with Graviton/Arm. Let's compare. This was easy because we had direct-comparison specint2006 scores.
specint2006, single-thread, normalized to GHz
Graviton2 +14% over Rome
specint2006, single-thread, raw
Rome +16.2% over Graviton2
It appears that there likely is an IPC advantage of Arm in those given setups. which doesn't matter much since Rome can clock higher, giving it a 16% lead in raw single-threaded specint2006 score.
Multi-thread
This was harder, not entirely apples to apples, which I'll discuss below.
Compare:
(1) Graviton2 specint2006 MT 64v CPU rate scores
(2) Rome 7742 64 cores in a 2P system (128 cores) and divide by 2 to normalize to 64 cores
(3) 7601 32 cores in a 2P system (total 64 cores)
Now, we can talk about Graviton2 not being SMT-enabled, hence limiting its performance (it does, but wouldn't make a difference against 7742). Or about whether using 7742 in 2P and dividing by 2 is fair. However, if anything, I think it hampers EPYC performance to have their chips in this comparison in a 2P configuration.
Here are the results, in brief:
specint2006, multi-thread, raw
Graviton2 - 100%
7601 - 115%
7742 - 125% ((( edited from previous, I made a formula error in Excel )))
Granted, none of this is apples to apples yet until they do a direct head-to-head comparison. Arm is doing something, but it's still many steps behind in the server market in my estimation. It's slower than 7601 in 2P (32 x 2 = 64 cores) and 7742 in 2P / 2.
So the brand new 2020 Graviton2 is 80% the speed of 2019's 7742. And AMD still have Milan to release this year.