Is there a way to replace Pthread threading backend to OpenMP?

mukula_seethi · 2025-01-27T04:02:34.654Z

I have done benchmarking of MongoDB using YCSB tool. I observe that it takes more time to run workloads on ARM machine compared to X86. I am curious to know if there is a way to implement OpenMP threading in MongoDB. If yes, it would be of great help if someone could help me do that.

Chris_Kelly · 2025-02-07T23:04:55.646Z

Hi @mukula_seethi.

Regarding ARM performance differences:

YCSB and the topology used are not always good predictors of real world performance
We run hundreds of benchmarks and workloads and some perform better and some perform worse.

Regarding threading backend changes:

MongoDB doesn’t officially support changing this.
My initial understanding is it would require a number of code changes to support.
I’m initially unsure of how much work this would be to try. I think it would be an interesting experiment for comparison, depending on the level of engineering effort involved here.

Ger_Hartnett · 2025-02-10T10:18:28.515Z

Hi @mukula_seethi : as my colleague Chris said, some workloads perform better on X86 and some on Arm. Sometimes it can depend on the exact CPU of each kind that you compare. I would be surprised if switching to OpenMP was the only way to close the performance gap for your workload. If your organization has a commercial relationship with MongoDB, I suggest contacting our Technical Services team. They have successfully helped many customers tune MongoDB performance for specific workloads and CPUs.