Linux 5.13 To Add Perf Support For Intel Alder Lake
Supporting the performance counters/events for Intel Alder Lake processors was more tricky than their usual new CPU enablement due to the new hybrid architecture. With Alder Lake featuring a mix of Golden Cove high performance cores and the low-power Gracemont cores, special handling is necessary within the perf subsystem and other select areas of the kernel due to the different capabilities between the high performance and power-saving CPU cores.
The Intel perf code within the Linux kernel saw hybrid PMU support introduced and a lot of other code refactoring needed due to the hybrid design of Alder Lake. Within the context of perf, the Golden Cove cores are using the cpu_core PMU while the Gracemont cores are using the cpu_atom PMU. These PMUs support different capabilities with "cpu_core" being similar to Sapphire Rapids while "cpu_atom" is close to Tremont.
One of the patches does note that with Intel Alder Lake platforms, from the BIOS it will be possible to disable the CPU cores of a particular CPU type. This capability will also exist from the Linux command line as well, in making for interesting benchmark comparisons and testing.
The perf bring-up for Intel Hybrid Technology and Alder Lake is in perf/core ahead of the Linux 5.13 cycle kicking off.
Intel 12th Gen Core "Alder Lake" processors are expected to debut later this calendar year. At this point it appears most of the Alder Lake enablement work is out there and on its way into appearing in upstream, released components prior to launch. Stay tuned for more on the Linux support/status as the launch nears.
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