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Thanks.

Just to confirm, the openmp reflects threads and not cores? In other words, on we have a 4 core machine with hyperthreading, so with 4 cores we have 8 threads available.

In that scenario, would the -openmp 4 option reflect 4 cores/8 threads or just 4 threads.

Thanks again.

d.m. ________________________________ From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Greve, Douglas N.,Ph.D. DGREVE@mgh.harvard.edu Sent: Wednesday, November 18, 2020 6:09 PM To: freesurfer@nmr.mgh.harvard.edu freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] -openmp vs -threads, -parallel options in recon-all

They are exactly the same. The two flags go to the same code. ________________________________ From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of d m fmrilog@outlook.com Sent: Wednesday, November 18, 2020 5:59 PM To: freesurfer@nmr.mgh.harvard.edu freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] -openmp vs -threads, -parallel options in recon-all

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Hello,

What is the difference between the -openmp and -threads option for recon-all?

Do they reflect the same thing: Number of threads used concurrently?

If we want to use 10 threads for the recon-all command, which option should we use? -openmp or -threads? How does this relate to the -parallel option?

Does every part of recon-all use multi-threading or only does only a subset of parts within recon-all use multi-threading?

Thanks in advance.

d.m.