* Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> [2023-11-15 10:57:08]:
> 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. > > > > For example: Lets says there are two 8-core Shared LPARs that are > > actually sharing a 8 Core shared physical pool, each running 8 threads > > each. Then Consolidating 8 threads to 4 cores on each LPAR would help > > them to perform better. This is because each of the LPAR will get > > 100% time to run applications and there will no switching required by > > the Hypervisor. > > > > Will this patch consolidate things to first 8 threads or just the one > Big core? /me continues to look at other patches and wonder whether 4/5 > should come before this? It will consolidate 1 thread per small core aka SMT domain or 2 threads per Big core. If the load is such that there are more unbound threads than SMT domains, asym packing will not kick-in. 4/5 would make sense only once we enable asym_packing above SMT domain. > > > > > > To achieve this, enable SD_ASYM_PACKING flag at CACHE, MC and DIE level > > when the system is running in shared processor mode and has big cores. > > > > Signed-off-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com> > > > -aneesh -- Thanks and Regards Srikar Dronamraju
