[Openmp-commits] [PATCH] D102188: [OpenMP] Add experimental nesting mode

[Terry Wilmarth via Phabricator via Openmp-commits]

tlwilmar added a comment.

In D102188#2755329 <https://reviews.llvm.org/D102188#2755329>, @tlwilmar wrote:

> In D102188#2752410 <https://reviews.llvm.org/D102188#2752410>, @ye-luo wrote:
>
>> Why "12 threads per parallel region" instead of 24? I thought hyper-threads are used by default. Maybe you assume no-SMT in your example? it will be helpful if you make it clear.
>
> Yes, it works that way if SMT is available. So, if there are 2 threads available per core, it would allow for a third nesting level, with size 2.

I should also add, since it uses whatever topology hwloc discovers, if it sees NUMA nodes, tiles, etc., it adds levels for those too -- any level in the topology that is distinct and has more than one item gets a nesting level.


Repository:
  rOMP OpenMP

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D102188/new/

https://reviews.llvm.org/D102188