--threads not respected by openblas / default --threads to number of CPU cores

[klosax]

By default openblas will utilize maximum available threads.

You could set the threads in openblas by using

void goto_set_num_threads(int num_threads);
void openblas_set_num_threads(int num_threads);

https://github.com/xianyi/OpenBLAS#setting-the-number-of-threads-at-runtime

The default for --threads is std::thread::hardware_concurrency() which returns the max threads including hyper-threads. This is not the same as the number of CPU cores. Using threads == cores usually gives the best performance. Here is how you can determinate the number of CPU cores: https://github.com/ggerganov/llama.cpp/blob/d783f7982e0e823a2626a9956359c0d36c1a7e21/examples/common.cpp#L34-L68

[leejet]

Thanks for your suggestion.
I've already set the default value of n_threads to the number of physical cores. However, I do think that GGML should control the number of threads for BLAS. Would you be willing to create an issue in the GGML repository regarding this matter?

[klosax]

Great! I created an issue about the openblas threads here ggml-org/ggml#452

[klosax]

Closed the issue since there is no real benefit of using openblas at all.

[leejet]

Should be fixed now