Can we just postpone these changes to next year?
The mixture of performance and efficiency CPUs in Intel’s 12th-gen Core processors, code-named Alder Lake, hasn’t just caused problems for some Windows gamers – it’s led to complications for Linux. Phoronix’ Michael Larabel noticed that Release Candidate 1 of the future kernel ran slower than expected on Alder Lake motherboards.. What may be a partial fix, at least, has just landed. This performance regression involves two related problems. What’s interesting is that the origins of at least one of the issues affecting the latest Intel chips lies in a totally different architecture. Earlier this year, Intel officially canned Lakefield, its first effort at hybrid chips – but Lakefield’s Tremont efficiency cores live on. They are the basis for a range of specialist server processors, such as the network-infrastructure-oriented Atom P5900 series, codenamed «Jacobsville» and «Snow Ridge». These are manycore chips with eight to 24 Atom cores, arranged in clusters which share resources such as cache memory. Huawei subsidiary Hisilicon’s Kunpeng 920, a manycore ARM chip, shares a similar clustered design. Which is the reason that a cluster-aware scheduling patch was submitted together by Intel and HiSilicon engineers. It makes the kernel’s scheduler aware that clusters of cores have shared cache. The goal of this on-by-default scheduling system is to balance the threads running in each cluster.
