Friday, February 23rd 2024
Intel's Desktop and Mobile "Arrow Lake" Chips Feature Different Versions of Xe-LPG
Toward the end of 2024, Intel will update its client processor product stack with the introduction of the new "Arrow Lake" microarchitecture targeting both the desktop and mobile segments. On the desktop side of things, this will herald the new Socket LGA1851 with more SoC connectivity being shifted to the processor; and on the mobile side of things, there will be a much-needed increase in CPU core counts form the current 6P+8E+2LP. This low maximum core-count for "Meteor Lake" is the reason why Intel couldn't debut it on the desktop platform, and couldn't use it to power enthusiast HX-segment mobile processors, either—it had to tap into "Raptor Lake Refresh," and use the older 14th Gen Core nomenclature one last time.
All hopes are now pinned on "Arrow Lake," which could make up Intel's second Core Ultra mobile lineup; its first desktop Core Ultra, and possibly push "Meteor Lake" to the non-Ultra tier. "Arrow Lake" carries forward the Xe-LPG graphics architecture for the iGPU that Intel debuted with "Meteor Lake," but there's a key difference between the desktop- and mobile "Arrow Lake" chips concerning this iGPU, and it has not just to do with the Xe core counts. It turns out, that while the desktop "Arrow Lake-S" processor comes with an iGPU based on the Xe-LPG graphics architecture; the mobile "Arrow Lake" chips spanning the U-, P-, and H-segments will use a newer version of this architecture, called the Xe-LPG+.Intel tends to give its desktop S-segment and enthusiast mobile HX-segment processors their smallest tiers of iGPUs to accommodate the relatively higher CPU core counts. In comparison, it tends to give its mobile U, P, and H-segments better endowed iGPUs with higher shader counts, with the guiding principle being that these notebooks tend to lack discrete graphics, and so you'd want to give users the best possible graphics from the processor.
It's likely that Intel is extending this principle even to the graphics architectures behind its future iGPUs. At this point, we don't exactly know what constitutes the "+" in Xe-LPG+. One line of speculation holds that Intel might be updating the media accelerators and display engines of the iGPU while retaining the Xe-LPG ISA for the Xe Cores. But it turns out that Intel has done the opposite—a Coelacanth's Dream article says that Xe-LPG+ is an update to the ISA side of things, rather than to ancillaries such as media or display.
Apparently, LPG+ gets support for DPAS (dot product accumulate systolic), something that's already available on the Xe-HPG, but which the original iteration of Xe-LPG lacks. DPAS enables FP16, BF16, and INT4 multiplication with 16 or 32 bits accumulate. Xe-LPG is an "in between" to the Xe-LP architecture powering older generation Intel iGPUs; and the Xe-HPG powering its Arc discrete GPUs. Xe-LPG features the full DirectX 12 Ultimate machinery from the Xe-HPG, but lacks its XMX AI acceleration engine. XeSS falls back to a DP4a codepath on Xe-LPG.
Intel is expected to debut "Arrow Lake" in Q4-2024.
All hopes are now pinned on "Arrow Lake," which could make up Intel's second Core Ultra mobile lineup; its first desktop Core Ultra, and possibly push "Meteor Lake" to the non-Ultra tier. "Arrow Lake" carries forward the Xe-LPG graphics architecture for the iGPU that Intel debuted with "Meteor Lake," but there's a key difference between the desktop- and mobile "Arrow Lake" chips concerning this iGPU, and it has not just to do with the Xe core counts. It turns out, that while the desktop "Arrow Lake-S" processor comes with an iGPU based on the Xe-LPG graphics architecture; the mobile "Arrow Lake" chips spanning the U-, P-, and H-segments will use a newer version of this architecture, called the Xe-LPG+.Intel tends to give its desktop S-segment and enthusiast mobile HX-segment processors their smallest tiers of iGPUs to accommodate the relatively higher CPU core counts. In comparison, it tends to give its mobile U, P, and H-segments better endowed iGPUs with higher shader counts, with the guiding principle being that these notebooks tend to lack discrete graphics, and so you'd want to give users the best possible graphics from the processor.
It's likely that Intel is extending this principle even to the graphics architectures behind its future iGPUs. At this point, we don't exactly know what constitutes the "+" in Xe-LPG+. One line of speculation holds that Intel might be updating the media accelerators and display engines of the iGPU while retaining the Xe-LPG ISA for the Xe Cores. But it turns out that Intel has done the opposite—a Coelacanth's Dream article says that Xe-LPG+ is an update to the ISA side of things, rather than to ancillaries such as media or display.
Apparently, LPG+ gets support for DPAS (dot product accumulate systolic), something that's already available on the Xe-HPG, but which the original iteration of Xe-LPG lacks. DPAS enables FP16, BF16, and INT4 multiplication with 16 or 32 bits accumulate. Xe-LPG is an "in between" to the Xe-LP architecture powering older generation Intel iGPUs; and the Xe-HPG powering its Arc discrete GPUs. Xe-LPG features the full DirectX 12 Ultimate machinery from the Xe-HPG, but lacks its XMX AI acceleration engine. XeSS falls back to a DP4a codepath on Xe-LPG.
Intel is expected to debut "Arrow Lake" in Q4-2024.