Srikar Dronamraju <sri...@linux.vnet.ibm.com> writes: > If there are shared processor LPARs, underlying Hypervisor can have more > virtual cores to handle than actual physical cores. > > Starting with Power 9, a big core (aka SMT8 core) has 2 nearly > independent thread groups. On a shared processors LPARs, it helps to > pack threads to lesser number of cores so that the overall system > performance and utilization improves. PowerVM schedules at a big core > level. Hence packing to fewer cores helps. >
.... > +/* > + * On shared processor LPARs scheduled on a big core (which has two or more > + * independent thread groups per core), prefer lower numbered CPUs, so > + * that workload consolidates to lesser number of cores. > + */ > +static __ro_after_init DEFINE_STATIC_KEY_FALSE(splpar_asym_pack); DEFINE_STATIC_KEY_FALSE_RO ? > + > /* > * P9 has a slightly odd architecture where pairs of cores share an L2 cache. > * This topology makes it *much* cheaper to migrate tasks between adjacent > cores > @@ -1011,9 +1018,20 @@ static int powerpc_smt_flags(void) > */ -aneesh
