Threadripper also only has 8MB of L3 cache per CCX, and you can't hold more than 8MB of data. (true, there are 4x CCX per chip, but you can't "combine" the datasets. You're effectively limited to 8MB per 4-cores. To communicate cross-CCX requires an expensive ping to main-memory) Its a great architecture, but cross-CCX communication is relatively slow and definitely is a concern for some work problems.

Power9 has 120MB of L3 cache that's shared between all cores. Which means you can ACTUALLY have a full 120MB-sized problem set and share all that information between cores.

In short: Threadripper is great for sure, but its not necessarily a fair comparison. In an apples-to-apples comparison (ie: Monero Mining), it seems like a Power9 server is 3x better than Threadripper (Power9 gets ~3000 hash/sec, while Threadripper is roughly 1000 hash/sec).

https://www.phoronix.com/scan.php?page=news_item&px=POWER9-C...

> Using the xmr-stak-power PPC64LE-focused Monero miner, they are seeing great performance with it running on dual pre-production 16-core POWER9 processors. There's a hash rate of 2945H/s while this POWER9 system is pulling 350 Watts DC power.

And mind you: Monero / Cryptonight only uses 2MB of L3 per core. So that's practically Threadripper's ideal problem. Imagine if you actually had a dataset that was larger than the 8MB per CCX that Threadripper is limited to.

Not to hate on Threadripper at all. Its cheap and high performance. I'm seriously considering a Threadripper system myself. But these Power9 specs are incredible, and I'd definitely like to test one if I could afford one.

That's a dual socket system with 16 cores per socket. Dual socket Epyc 7351 (also 16 core per socket) is faster and more power efficient than that. 3200H/s at 332W.

https://www.youtube.com/watch?time_continue=226&v=CS7M392Ia_...

I'm sure there are workloads that really do benefit from the huge unified L3, but it seems like a pretty small niche.

I really hope AMD releases a 7601 variant that is clocked similarly to the threadripper chips.

The cores are not directly comparable. The Power chip has significantly more hyper threads (and the resources to back them).

For those not in the know:

Each Power9 is consisting of either 2-super slices or 4-super slices, depending on which Power9 you get. (Corresponding to 4x SMT or 8x SMT respectively).

Threadripper has 4x integer pipelines, 4x floating point pipelines, and 2x load/store units (called AGUs by AMD) and supports 2-threads (aka: 2x SMT).

So Threadripper definitely is "broad", but Power9 is "broader". The 8x SMT Power9 can perform 8x loads / stores per cycle per core, while AMD's Threadripper can only perform 2x loads/stores per cycle per core.

The last presentation on Power at Hotchips left me with the impression that "Core" in IBM terms is 9/10ths marketing speak and whatever Power might have that their engineers might think of as "cores" probably has little to do with what their marketing people are telling their customers and software vendors who do their licensing "per core".

Could you expand a bit on this? Are you saying they are inflating their core count or the reverse? Everything I've looked at indicates significantly more powerful cores.

Sorry but I just noticed this reply. I don't want to claim that IBM is "inflating" their core count, nor the inverse. Rather that what passes for what we might think of as a "core" based on the ways software vendors describe things isn't directly transferable to what IBM has actually built.

IBM has extremely flexible hardware which, using IBM's hypervisor, can be configured on the fly to present itself in a number of different ways. For example: few powerful compute units, many medium compute units, or very many less capable compute units.

So right up front the idea (which a lot of people might assume without really thinking about) that a given chip has a fixed number of "cores" doesn't really hold true. More to the point the next question that presents itself "what makes up for a core and what determines how many a given processor has" is best answered with "it depends" (at least as far as IBM Power goes).

One of the main reasons this matters is that all sorts of businesses use the idea of "cores" as a fixed entity as part of their pricing structures... and now it's all muddied.

They "inflated" it from 12 to 24 but recently it looks like they deflated it back to 12 cores. However you count it, a full Power9 chip is competitive with a 24-core Xeon or 32-core Epyc.

A full POWER9 chip should be compared with a 48-core Xeon.

In regards to cores, the distinction is between the PowerVM and Linux (OpenPOWER/PowerNV) ecosystem variants. Both are made to process 96 threads, but the difference is in whether the thread processing units are grouped eight to a core (SMT8) or four to a core (SMT4).

The PowerVM version, some say for licensing reasons, gets the SMT8 cores. Either way, you get 96 threads:

12 cores * SMT8 = 96 threads 24 cores * SMT4 = 96 threads