Father Of Zen Jim Keller Predicts Zen 5 Will Deliver A Massive IPC Uplift
Jim Keller's been getting around in the last decade or so. Back in the early 00s, he was critical to the development of the Athlon 64 at AMD, and in more recent years, he's been at Apple, Tesla, Intel, and AMD again before joining AI-focused chip creator Tenstorrent where he has quickly become CEO.
Every architecture deployed by any company after Jim's tenure there has been nothing short of solid gold, so the man clearly knows what he's talking about. Hopefully that's the case with his work at Tenstorrent, where the company just put on a show talking about its upcoming Ascalon CPU. Ascalon is slated to deliver industry-leading performance-per-watt for integer math—the most important type of math for AI.
We're not here to talk about Ascalon today, though. After all, Ascalon isn't an x86-64 CPU, and thus is not likely to be particularly interesting to PC enthusiasts who primarily run Windows. What is particularly interesting is a certain chart that Keller showed during his presentation that compares Tenstorrent's new Ascalon processor against a variety of competitors, including Amazon's Graviton, AMD's EPYC, NVIDIA's Grace, and Intel's Xeon CPUs.
Tenstorrent claims that Ascalon can achieve superior performance to almost everything on the graph if the design meets its goals and hits a rate of 2.2 SPECIN2017-score-per-GHz. "Almost" everything, because the graph includes a prediction for the SPECINT2017 rate of AMD's Zen 5 architecture, and the prediction is pretty potent: 8.84, compared to 7.45 for Intel's Sapphire Rapids, 7.44 for NVIDIA's Grace, and 6.80 for AMD's Genoa, based on Zen 4.
Now, Jim Keller was indeed a primary designer on Zen, but it's been a while since he was last at AMD, and officially, he probably has no idea what Zen 5 is capable of. Officially. It's not difficult to imagine a world where Keller knows full-well what Zen 5 can do due to having friends and colleagues still at AMD, though. Notably, the NVIDIA Grace score says "Projected", but the AMD Zen5 prediction says no such thing.
The relevant portion starts at around 42 minutes.
It's important to understand that SPECINT is a benchmark of a processor core's ability to process integer math instructions. It's a single-core benchmark, meaning that this performance uplift for Zen 5 isn't the result of AMD's tendency to stack on more cores than the competition. Perhaps even more impressive is that despite the massive 30% performance gain over Zen 4, Keller seems to think Zen 5 will hold power consumption steady at just under 250 watts.
Of course, Ascalon is supposed to come within striking distance of Zen 5's performance, and it is expected to do it while staying at or around a 200-watt TDP. That's impressive stuff, and if it hits its goals, Tenstorrent could really be disruptive in the AI market. Here's a tip of the hat to Keller and his team for both their future success as well as the interesting Zen 5 prediction.