[R] Assigning cores

[Jeff Newmiller]

Do you have 20 actual cores or 10 cores/20 threads? detectCores() doesn't usually know the difference but the CPU may be too busy accessing memory to let that last thread get any useful work done. I often find that allocating real cores is more practical than thinking in terms of thread so try allocating 9 workers and watch your cpu usage.

Experiment with your settings... the right balance may be dependent on your other activities as well as your hardware, since your analysis may not be completely memory access limited and threads might make (some) sense for you.

On September 3, 2020 10:44:34 AM PDT, Leslie Rutkowski <leslie.rutkowski using gmail.com> wrote:
>Hi all,
>
>I'm working on a large simulation and I'm using the doParallel package
>to
>parallelize my work. I have 20 cores on my machine and would like to
>preserve some for day-to-day activities - word processing, sending
>emails,
>etc.
>
>I started by saving 1 core and it was clear that *everything* was so
>slow
>as to be nearly unusable.
>
>Any suggestions on how many cores to hold back (e.g., not to put to
>work on
>the parallel process)?
>
>Thanks,
>Leslie
>
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

-- 
Sent from my phone. Please excuse my brevity.