Parallel Computing Toolbox - Limit of number of workers - R2021a

Hi,

I am using Matlab R2021a along with the Parallel Computing Toolbox.

I would like to know how many cores can PCT support? For example, can it support a machine with 128 physical cores (quad processor motherboard)?

I was searching the Parallel Computing User Guide, but there wasn't any hard limit on the cores, only a note in the "Pool Size and Cluster Selection" section (p. 2-58), saying:

"A local cluster running on the client machine requires nolicensing beyond the one for Parallel Computing Toolbox. The limit on the number of workers is high enough to support the range of known desktop hardware".

So what exaclty is that limit?

Thank you in advance for your supoprt and time.

Kind regards,

Nassos

Answer 1

[Raymond Norris]

Based on what your stating, I'm gather it's a single motherboard, with 32 sockets, each socket with 4 physical cores. Is that right? If not, give a bit more detail about your hardware.

• Single or multi-motherboard?
• sockets per motherboard
• cores per socket
• Hyperthreading enabled/disabled

And, are you running Windows or Linux?

Lastly, what does this return

feature('numcores');

[nassos]

Hi,

thanks for your response.

I am looking to buy a new machine which will have a single quad-socket motherboard (so 4 sockets) with 4 chips (32 physical cores in each chip). That is why I would like to understand if there is a limit on the number of cores that can be used form the PCT. And aparently from the PCT user guide there is, but I cannot find where it is documented.

If for example PCT can support only 28 cores, there is no point in building a machine like that and I can restrict myself to a single socket motherboard and single chip with 32 physical cores.

Can you please point me to a documentation that reports this limit?

Thank you in advance for your help.

Kind regards,

Nassos

[Raymond Norris]

PCT will support 128 cores on a Linux machine, bound to a single motherboard.

As an example, I've started a 48-core, bare metal machine on AWS. Notice I'm able to start a local pool of 48 workers.

I'll see if I can jump on a 128 core machine later and show you it running as well.

[nassos]

Thanks!

[Walter Roberson]

I am not certain the same is true for Windows, as Windows has a limit of 64 cores per process group.

I have read that there are third-party drivers that can bundle together cores to extend the effective number of cores per process group.

[Raymond Norris]

Agreed @Walter Roberson