Thursday, May 30th 2024

Intel's "Skymont" E-core Posts a Double-digit IPC Gain Over "Crestmont": Leaked Presentation

Amid all the attention the next-generation "Lion Cove" P-cores powering the upcoming "Lunar Lake" and "Arrow Lake" microarchitectures get as they compete with AMD's "Zen 5," it's easy to lose sight of the next-generation "Skymont" E-cores that will feature in both the upcoming Intel microarchitectures, and as standalone cores in the "Twin Lake" low-power processor. Pictures from an Intel presentation, possibly to PC OEMs, got leaked to the web. These are just thumbnails, we can't see the whole slides, but the person who took the pictures captioned them in a now-deleted social media post on the Chinese microblogging platform Weibo.

And now, the big reveal—the "Skymont" E-core is said to offer a double-digit IPC gain over the "Crestmont" E-core powering the current "Meteor Lake" processor, which in itself posted a roughly 4% IPC gain over the "Gracemont" E-cores found in the "Raptor Lake" and "Alder Lake" microarchitectures. Such an IPC gain over "Gracemont" should make the "Skymont" E-core match the IPC of the "Sunny Cove" or "Willow Cove" P-cores powering the "Ice Lake" and "Tiger Lake" microarchitectures, respectively, which were both within the 90th percentile of the AMD "Zen 3" core in IPC.
Intel is achieving this double-digit IPC gain over "Crestmont" through an improved branch prediction unit, a broader 9-wide Decode unit compared to the 6-wide Decode unit of "Crestmont," and an 8-wide integer ALU, compared to 4 Integer ALU on its predecessor, a dependency optimization in the out-of-order engine, and deeper queuing across the engine. The E-cores might still be arranged in clusters that share an L2 cache among a certain number of cores.
Source: HXL (Twitter)
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27 Comments on Intel's "Skymont" E-core Posts a Double-digit IPC Gain Over "Crestmont": Leaked Presentation

#26
DavidC1
"Double-digit" gains are actually 38% on Int and 68% in FP. It's going to beat Golden Cove folks. Lion Cove may be under 10% faster in Int compared to Skymont since Skymont is going to end up being upwards of 10% or more above Golden Cove.
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#27
Darmok N Jalad
InVasManiWhat do you expect in certain workload scenario's the E cores are for MT headroom they aren't intended primary cores, but secondary cores. Peak ST performance will nearly always be on the P cores due HT and clock speed differences, but peak MT favors E cores. The whole point is really to spread the work around for stuff that doesn't need peak ST performance beyond 6 to 8P cores or whatever. Depending on workload scenario's OC on P cores or E cores provides relative advantages and disadvantages.

Typically just dropping E cores clock speeds a bit and pushing P cores a bit harder and/or ensuring they can boost longer w/o thermal problems is fine in practice. Most workloads don't need peak ST performance more than 8 cores anyway. I mean hell we use to live in a world where all we heard was four cores is all you need.

That's still fairly true a good amount of the time since most workloads aren't exactly pegging 8P cores to death or even more than 4P cores in many cases. Workloads vary of course and you can point to whichever data you wish to in order to illustrate or make most points of topic banter arguments.

I'm satisfied with my 14700K for what I got it for it was good deal. Is it perfect not exactly, but does it matter to me not really. Do I even notice in daily operation not all.
Except that's often not what I'm seeing. For example, do a copy/paste of a few thousand rows of data into a spreadsheet with calcs. You'd think it would max out all the cores, but instead, it maxes out the 2 P cores of the i7 and the E cores barely do a thing. The sad thing is, these calcs aren't exactly elaborate math--some IFs SUMIFS, and some XLOOKUPS, and not a lot of dependency. It should be right in the MT wheelhouse, but it will often take my CPU what I feel is way too long. Maybe the E cores should be doing this task, and the scheduler is getting is screwed up, I dunno. All I know is I often observe MT tasks not using all the cores.
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