On Tue, Aug 04, 2020 at 09:03:07AM +0530, Srikar Dronamraju wrote: > On Power9 a pair of cores can be presented by the firmware as a big-core > for backward compatibility reasons, with 4 threads per (small) core and 8 > threads per big-core. cpu_smt_mask() should generally point to the cpu mask > of the (small)core. > > In order to maintain userspace backward compatibility (with Power8 chips in > case of Power9) in enterprise Linux systems, the topology_sibling_cpumask > has to be set to big-core. Hence override the default cpu_smt_mask() to be > powerpc specific allowing for better scheduling behaviour on Power.
Why does Linux userspace care about this?
