Re: [PATCH v2 2/6] powerpc/smp: Enable Asym packing for cores on shared processor

* Shrikanth Hegde [off-list ref] [2023-10-19 21:26:56]:

On 10/18/23 10:07 PM, Srikar Dronamraju wrote:

quoted

If there are shared processor LPARs, underlying Hypervisor can have more
virtual cores to handle than actual physical cores.

Starting with Power 9, a 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 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.

To achieve this, enable SD_ASYM_PACKING flag at CACHE, MC and DIE level.

This would have a conflict with tip/master. 
DIE has been renamed to PKG and Both changelog and code below should 
change DIE to PKG. 

Once the changes are part of powerpc/merge, will rebase and accomodate the
changes from DIE to PKG.


-- 
Thanks and Regards
Srikar Dronamraju