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Re: R, openBlas and max thread?
From: |
zimoun |
Subject: |
Re: R, openBlas and max thread? |
Date: |
Fri, 22 Feb 2019 16:11:40 +0100 |
Dear Eric,
Thank you for your answer.
On Wed, 20 Feb 2019 at 05:19, Eric Bavier <address@hidden> wrote:
> OpenBLAS will use as many threads as the OpenMP runtime will give it,
> which is by default one per CPU. I think this default does not take
> into account hyperthreads, which htop shows as a separate "cpu".
Yes for sure, htop shows hyperthreads number of CPU. :-)
Maybe I have wrong, but if hyperthread is activated, then why not use
it by default.
In other words, OpenMP should be set by default at "hyperthread CPU"
and not "physical CPU". I think Debian is doing that for example.
What do you think ?
> You can set the "OMP_NUM_THREADS" environment variable and OpenBLAS
> should pick it up. I don't know whether R does anything for setting
> OpenMP runtime settings.
I do not know neither.
Hum? R does not seems to use OMP_NUM_THREADS. I do not know.
All the best,
simon