The Intel 12th Gen Core i9-12900K Review: Hybrid Performance Brings Hybrid Complexity
by Dr. Ian Cutress & Andrei Frumusanu on November 4, 2021 9:00 AM ESTCPU Tests: SPEC MT Performance - DDR5 Advantage
Multi-threaded performance is where things become very interesting for Alder Lake, where the chip can now combine its 8 P-cores with its 8 E-cores. As we saw, the 8 E-cores are nothing to sneeze about, but another larger consideration for MT performance is DDR5. While in the ST results we didn’t see much change in the performance of the cores, in MT scenarios when all cores are hammering the memory, having double the memory channels as well as +50% more bandwidth is going to be extremely beneficial for Alder Lake.
As we noted, the DDR5 vs DDR4 results showcase a very large performance gap between the two memory technologies in MT scenarios. Running a total of 24 threads, 16 for the SMT-enabled P-cores, and 8 for the E-cores, Alder Lake is able to take the performance crown in quite a lot of the workloads. There are still cases where AMD’s 16-core setup with larger cores are able to perform better, undoubtedly also partly attributed to 64MB of on-chip cache.
Compared to the 11900K, the new 12900K showcases giant leaps, especially when paired with DDR5.
In the FP suite, the DDR5 advantage in some workloads is even larger, as the results scale beyond that of the pure theoretical +50% bandwidth improvement. What’s important for performance is not just the theoretical bandwidth, but the actual utilised bandwidth, and again, the doubled up memory channels of DDR5 here are seemingly contributing to extremely large increases, if the workload can take advantage of it.
In the aggregate results, there’s very clearly two conclusions, depending on whether you use the chip with DDR5 or DDR4.
With DDR4, Alder Lake and the 12900K in particular, is able to showcase very good and solid increases in performance, thanks to the IPC gains on the Golden Cove core, but most importantly, also thanks to the extra 8 Gracemont cores, which do carry their own weight. The 12900K falls behind AMD’s 5900X with DDR4, which is fair given the pricing of the chips here are generally in line with teach other.
With DDR5, the 12900K is able to fully stretch its multi-threaded performance legs. In less memory dependent workloads, the chip battles it out with AMD’s 16-core 5950X, winning some workloads, losing some others. In more memory dependent workloads, the DDR5 advantage is extremely clear, and the 12900K is able to blow past any competition, even slightly edging out the latest Apple M1 Max, released a few weeks ago, and notable for its memory bandwidth.
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mode_13h - Saturday, November 6, 2021 - link
> Consumers deserve non-broken products that aren’t sold via smoke and mirrors tactics.What's broken, exactly? They said you wouldn't have AVX-512. That someone figured out how to enable it is just bonus.
mode_13h - Saturday, November 6, 2021 - link
Why are you convinced it's so consequential?mode_13h - Saturday, November 6, 2021 - link
Oops, that was a response to:OG> The current situation is inexcusable.
Oxford Guy - Sunday, November 7, 2021 - link
That question is meritless.mode_13h - Sunday, November 7, 2021 - link
If the issue isn't terribly consequential, then why is it inexcusable? The gravity of alleged misconduct usually derives from its impacts.Oxford Guy - Monday, November 8, 2021 - link
I have been suspicious that you’re some sort of IBM AI. Posts like that go a long way toward supporting that suspicion.You were the poster who claimed it’s of little consequence. I was the poster who said it’s inexcusable. Either you’re AI that needs work or your mind is rife with confusion in your quest to impress the community via attempts at domination.
Not a good look, again. Posting your own claims as if they’re mine and using my claims to create a false incompetence situation is a bit better than your pathetic schoolyard taunts. So, perhaps I should praise you for improving the quality of your posts via being merely incompetent — like Intel’s handling of this situation you’re trying to downplay. I shouldn’t make that equivalence, though, as lying to the community in terms of a retail product is worse than any of your parlor tricks.
mode_13h - Tuesday, November 9, 2021 - link
> I have been suspicious that you’re some sort of IBM AI.No way. Their artificial intelligence is no match for my natural stupidity.
:D
> You were the poster who claimed it’s of little consequence.
No, I asked *you* why it's so consequential.
> I was the poster who said it’s inexcusable.
Which sort of implies that it's very consequential. If it's of not, then why would it be inexcusable?
> Either you’re AI that needs work or your mind is rife with confusion in your quest to
> impress the community via attempts at domination.
If you wouldn't waste so much energy posturing and just answer the question, maybe we could actually get somewhere.
I don't honestly care what the community thinks of me. That's the beauty of pseudonymity! I don't even need people to believe I'm somehow affiliated with a prestigious university. Either my points make sense and are well-founded or they aren't. Similarly, I don't care if you're "just" the Oxford garbage collector. If you contribute useful information, then we all win. If you're just trolling, flaming, or pulling the thread into irrelevant tangents, then we all lose.
The main reason I post on here is to share information and to learn. I asked what should be a simple question which you dismissed as meritless, and without explaining why. As usual, only drama ensues, when I try to press the issue. I always want to give people the opportunity to justify their stance, but so often you just look for some way to throw it back in my face.
This kind of crap is extremely low value. I hope you agree.
mode_13h - Saturday, November 6, 2021 - link
> and the sentence about how it could be eliminated in the future.It's true. Intel can disable instructions in microcode updates and in future steppings of the CPU. So, even having the BIOS option is no guarantee.
mode_13h - Saturday, November 6, 2021 - link
> Since the silicon is there, if they can get the scheduler to manage> heterogeneous (P/E) cores there is now no down side with enabling AVX-512.
This will not happen. The OS scheduler cannot compensate for lack of app awareness of the heterogeneous support for AVX-512. I'm sure that was fiercely debated, at Intel, but the performance downsides for naive code (i.e. 99%+ of the AVX-512 code in the wild) would generate too many complaints and negative publicity from the apps where enabling it results in performance & power regressions.
Oxford Guy - Saturday, November 6, 2021 - link
So, Alder Lake is a turkey as a high-end CPU, one that should have never been released? This is because each program has to include Alder Lake AVX-512 support and those that don’t will cause performance regressions?So, Intel designed and released a CPU that it knew wouldn’t be properly supported by Windows 11 — yet the public was sold Windows 11 primarily on the basis of how its nifty new scheduler will support this CPU?
‘The OS scheduler cannot compensate for lack of app awareness of the heterogeneous support for AVX-512’
Is Windows 11 able to support a software utility to disable the low-power cores once booted into Windows or are we restricted to disabling them via BIOS? If the latter is the case then Intel had the responsibility for mandating such a switch for all Alder Lake boards, as part of the basic specification.