[llvm] [llvm-exegesis] Add support for pinning benchmarking process to a CPU (PR #85168)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> Is this happening in practice, and does it make a significant difference on the output ?

Yes, at least if the system is doing other things/isn't quiet. The source of https://github.com/llvm/llvm-project/issues/80957 from what I can tell is that the benchmarking process gets swapped in and out, changing the values enough that there is a reasonable probability the reported result is negative. This patch won't fix that issue, but does prevent any potential interference from other processes.

https://github.com/llvm/llvm-project/pull/85168