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Intel's Lion Cove P-Core and Gaming Workloads
- samrus 1y ago122 points and no comments? Is this being botted or something?
- PhilipRoman 1y agoCould be. Usually it means the subject is too advanced for the average HN user yet something that they are interested in.
- adrian_b 1y agoSuch articles are very interesting for many people, because nowadays all CPU vendors are under-documenting their products. Most people do not have enough time or knowledge (or money to buy CPU samples that may prove to be not useful) to run extensive sets of benchmarks to discover how the CPUs really work, so they appreciate when others do this and publish their results. Besides learning useful details about the strengths and weaknesses of the latest Intel big core, which may help in the optimization of a program or in assessing the suitability of an Intel CPU for a certain application, there is not much to comment about it.
- HelloNurse 1y agoIt is an interesting but particularly non-actionable analysis: only a handful of engineers at Intel are in a position to design an improved Lion Cove, while the main takeaway for the game programmers who care about game workload performance is that nothing performs too badly and therefore general performance improvement techniques like accessing less memory are a good fit for this processor.
- whatever10 1y agoI mean what is there to comment. Intel botched another product release. It is just a sad state of affairs.
- Nursie 1y agoHow so? Not that I disbelieve, I just wasn't especially picking that up from the article.
- la_oveja 1y agothey still cannot reach power figures they had in the last, 3? generations. 13 and 14 series, which made these figures by literally burning themselves to the point of degradation. intel has no competition to amd in the gaming segment right now. they control both the low energy efficiency market and the high performance one.
- orthoxerox 1y agoDo they? I thought Lunar Lake was an incredibly good efficiency generation.
- high_na_euv 1y agoIt is
- adrian_b 1y agoWhile Lunar Lake has excellent energy efficiency and AMD does not really have any CPU designed for low power levels, Lunar Lake had also a very ugly hardware bug (sporadic failure of MWAIT to detect the waking event). This bug has disqualified Lunar Lake for me, and I really do not understand how such a major bug has not been discovered before the product launch (the bug has been discovered when in many computers running Linux the keyboard or the mouse did not function properly, because their events were not always reported to the operating system; there are simple workarounds for the bug, but not using MONITOR/MWAIT eliminates one of the few advantages that Intel/AMD CPUs have over Arm-based CPUs, so I do not consider this as an acceptable solution).
- FirmwareBurner 1y ago>122 points and no comments? Better no comments than having to trod through the typical FUD or off topic rants that tend to plague Intel and Microsoft topics.
- baq 1y agoexactly. I'm very happy to notice there are no 'x86 bad arm good' comments here as of now. a welcome change. also - or maybe, first and foremost - it's just a very good article.
- xxs 1y agoit's a very good article.
- wuming2 1y agoSubstack.
- onli 1y agoTo see what that means in practice, in my multi generational meta benchmark the 285K lands currently only on rank 12, behind the top Intel processors from the last two generations (i7-13700K and 14700K plus the respective i9) and several AMD processors. https://www.pc-kombo.com/us/benchmark/games/cpu https://www.pc-kombo.com/us/benchmark/games/cpu. The 3D cache just helps a lot in games, but the loss against the own predecessor must hurt even more.
- vladvasiliu 1y agoI don't fully follow this, so what has been gained with the new models? I seem to remember you'd need dedicated industrial cooling for the 14700k. Does the new model at least pump much less power?
- onli 1y agoSo, for one in other software the new processors do better. The 285K beats the i9-14900KS by a bit in my app benchmark collection (which is less extensive, but still). And second yes, according to https://www.computerbase.de/artikel/prozessoren/intel-core-ultra-200s-285k-265k-245k-test.90019/seite-5 https://www.computerbase.de/artikel/prozessoren/intel-core-u... for example they are less extreme in their energy usage and more efficient in general, albeit not more efficient than the AMD processors. But it is a valid question.
- KronisLV 1y ago> I don't fully follow this, so what has been gained with the new models? There were power efficiency gains, as well as nice productivity improvements for some workloads: https://www.youtube.com/watch?v=vjPXOurg0nU https://www.youtube.com/watch?v=vjPXOurg0nU For gaming, those CPUs were a sidegrade at best. To be honest, it wouldn't have been a big issue, especially for folks upgrading from way older hardware, if only their pricing wasn't so out of line with the value that they provide (look at their GPUs, at least there the MSRP makes the hardware good value).
- Aurornis 1y ago> I seem to remember you'd need dedicated industrial cooling for the 14700k. Those CPUs run hot, but it got exaggerated a lot online. It’s not hard to handle their heat with a good air cooler (even some of the $50 units like the Peerless Assassin) or a run of the mill closed loop water cooler. There are a lot of old notions in the gaming community that you need to keep CPUs under arbitrary temperature thresholds or that any throttling is bad. Modern CPUs and GPUs run themselves deep into the performance curves and slight throttling is barely noticeable.
- mort96 1y ago> E-Cores are turned off in the BIOS, because setting affinity to P-Cores caused massive stuttering in Call of Duty. I understand doing this for the purpose of specifically analyzing the P-core microarchitecture in isolation. However this does make the test less interesting for potential customers. I don't think many people would disable E-cores in BIOS if they bought this CPU, so for the purpose of deciding which CPU to buy, it would be more interesting to see results which factor in the potential software/scheduling issues which come from the E-core/P-core split. This isn't a criticism, just an observation. Real-world gaming results for these CPUs would be worse than what these results show.
- pjmlp 1y agoI think many haven't yet grasped the future is heterogeneous computing, especially, when many desktops are actually laptops nowadays. Software working poorly in such setup means no effort was made to actually make it perform well in first place. Games requiring desktop cases looking like a rainbow aquarium with top everything will become a niche, in today's mobile computing world, and with diminishing sales and attention spans, maybe that isn't the way to keep studios going.
- jama211 1y agoNot “no effort to make sure it performs well in the first place”, that isn’t fair. Lots of effort probably went into it performing well, just this case isn’t handled yet and to be fair this only impacts some people currently and there is a chance to update it. This just reads like “if they haven’t handled this specific case they’ve made no effort at all across the board” which seems extreme.
- pjmlp 1y agoThen why taking the effort to look better that it actually is?
- mort96 1y agoAre you asking why the author of this article is disabling e-cores? That'd be because this article is trying to analyze Intel's Lion Cove cores. The e-cores and issues caused by heterogeneous cores are therefore irrelevant, only the P-cores are Lion Cove.
- moffkalast 1y agoSay, is there any talk about Intel working on an AMD Strix Halo competitor, i.e. quad channel LPDDR5X in the consumer section?
- jeffbee 1y agoI am still waiting on evidence that memory architecture helps anyone.
- moffkalast 1y agoI'm pretty sure memory is still the main bottleneck in the vast majority of operations, and why the X3D is such a monster with so much L3 cache. There's almost nothing that doesn't benefit from having twice the memory bandwidth.
- jeffbee 1y agoDid you read the article?
- moffkalast 1y agoThe article literally says this very thing? > Lion Cove suffers harder with backend memory latency, but far less from frontend latency. Part of this can be explained by Zen 4’s stronger data-side memory subsystem. The AMD Ryzen 9 7950X3D I previously tested on has 96 MB of L3 cache on the first die, and has lower L3 latency than Lion Cove in Intel’s Arrow Lake platform. Beyond L3, AMD achieves better load-to-use latency even with slower DDR5-5600 36-36-36-89 memory. Intel’s interconnect became more complex when they shifted to a chiplet setup, and there’s clearly some work to be done. They only compared three games of roughly the same genre in terms of mechanics which is not exactly a representative benchmark either, even for games. The average shooter with a fixed map and say, Minecraft, have vastly different memory access demands.
- jeffbee 1y ago
- deleted 1y ago[deleted]
- fortmeier 1y agoI would like to understand more of the article, which book should I read?
- yvdriess 1y agohttps://archive.org/details/computerarchitectureaquantitativeapproach6thedition https://archive.org/details/computerarchitectureaquantitativ...
- throwaway31131 1y agoThat's more of a graduate level book. If you would like a book by the same author, that is lighter in content but much more approachable, I recommend this version: https://www.cs.sfu.ca/~ashriram/Courses/CS295/assets/books/HandP_RISCV.pdf https://www.cs.sfu.ca/~ashriram/Courses/CS295/assets/books/H... And don't forget to look at the online appendices on the MK website. They are also all very good.
- celeritascelery 1y agoAnother thing you could do if you want to understand more of the details is open this article with an LLM and ask it questions. Have it explain unfamiliar terms and comparisons to you
- fschutze 1y agoFantastic article -as always. Regarding the top-down analysis: I was a bit surprised to see that in ~1/5 of the cases the pipeline stalls b/c the pipeline is Frontend Bound. Can that be? Similarly, why is Frontend Bandwidth a subgroup of Frontend Bound? Shouldn't one micro-op be enough?
- yvdriess 1y agoTake front end bound with a grain of salt. Frequently I find a backend backpressure reason for it, e.g. long-tail memory loads needed for a conditional branch or atomic. There are limitations to sampling methods and top down analysis, consider it a start point to understanding the potential bottlenecks, not the final word.
- fschutze 1y agoInteresting. You realize this by identifying the offending assembly instructions and then see that one operands comes from memory?
- yvdriess 1y agoThere's no single good way, but yes as you said, logical deduction based on the surrounding instructions and their hardware counters is a way to do it. Instruction B might be collecting a ton of hardware counted cycles, but it could be because instruction A it depends on is slow. Sometimes, those dependencies are even implicit, since x86 is in-order commit some instructions like lock/atomics have implicit and dynamic dependencies based on what is in the reorder buffer at the time. To give a concrete example I encountered analysing a GC: traversing the object graph in a loop means calculating the address of an object, loading that object, doing some work on it and then grabbing the bits to calculate the children to visit next. This creates a long brittle chain of data-dependent conditionals, depending on a calculation that eventually came from a much earlier load. That conditional branch might be 30/70 taken/untaken, so the branch predictor often does not speculate, reducing the ILP and making it harder to hide the load's latencies. Now, dear Watson, would you say the blame is to the front end? There are no stalls when all the loads go to fast cache, only when there is the occasional remote LLC hit, DRAM hit or god forbid cross-NUMA hit. What if I tell you that there's an atomic operation to mark the object as visited, which is fast in itself but can only be issued when all prior loads have completed and stops from newer instructions to be issued while it hasn't been committed. You need to look at a whole bunch of surrounding instructions and a variety of hardware counters to start forming a picture. Insert Always Sunny in Philadelphia meme with the red wire crime board here.
- Avlin67 1y agoI suggests using a Xeon w7 2595X so that you have 26P cores and 0E cores
- ece 1y agoAnother article with some original slides from Intel. https://www.hwcooling.net/en/intels-new-p-core-lion-cove-is-the-biggest-change-since-nehalem/ https://www.hwcooling.net/en/intels-new-p-core-lion-cove-is-...
- Sohcahtoa82 1y agoSeeing that the Lion Cove L3 cache takes ~83 cycles while the previous generation was only ~68 cycles explains why Lion Cove is an utter dud of a CPU for gaming and why it loses to the Raptor Cove in so many gaming benchmarks. Meanwhile, the Zen 5 is only 47 cycles, and if you get the X3D variant, you get a TON of that L3 cache, which just turbo-charges games. How did Intel allow such a major performance regression in their L3 cache?