On Thu, Mar 08, 2018 at 09:41:17PM +0100, Brice Goglin wrote: > > > Is there a good reason for diverging instead of adjusting the > > core_sibling mask? On x86 the core_siblings mask is defined by the last > > level cache span so they don't have this issue. > > No. core_siblings is defined as the list of cores that have the same > physical_package_id (see the doc of sysfs topology files), and LLC can > be smaller than that. > Example with E5v3 with cluster-on-die (two L3 per package, core_siblings > is twice larger than L3 cpumap): > https://www.open-mpi.org/projects/hwloc/lstopo/images/2XeonE5v3.v1.11.png > On AMD EPYC, you even have up to 8 LLC per package. Right, I missed the fact that x86 reports a different cpumask for topology_core_cpumask() which defines the core_siblings exported through sysfs than the mask used to define MC level in the scheduler topology. The sysfs core_siblings is defined by the package_id, while the MC level is defined by the LLC. Thanks for pointing this out. On arm64 MC level and sysfs core_siblings are currently defined using the same mask, but we can't break sysfs, so using different masks is the only option. Morten -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
