I am not familiar with using Slurm with VMs, but do note that Slurm can behave a bit "unexpectedly" with memory constraints due to the memory consumed by OS, etc. E.g., if I had a 16 core machine with 64 GB of RAM and requested 16 cores with 4 GB/core, it would not fit on this machine because some of the RAM is being used by the OS. Whereas if I requested 3.75 GB/core it likely would fit.
As Michael Di Domenico, can you detail how you are concluding that 2 CPU cores are assigned to the 16 GB job? E.g. if your VM nodes are 2 core and 32 GB, then I would expect placing a 1 core 16 GB job will prevent another such job being scheduled to that node. I would suggest reducing your default/max RAM per core a little bit so you have a GB or two left over for the system, and things should work more as expected. On Tue, Sep 29, 2020 at 11:22 AM Luecht, Jeff A <jeff.lue...@pnc.com> wrote: > There are three pieces of information that may provide Useful: > > 1 - these are VMs and not physical servers > 2 - the OS is RedHat 7.8 > 2 - As far as I can tell, hyperthreading is not enabled, but will check > for sure > 3 - when we ask for 15Gb memory - we will only get 1 CPU > > -----Original Message----- > From: slurm-users [mailto:slurm-users-boun...@lists.schedmd.com] On > Behalf Of Michael Di Domenico > Sent: Tuesday, September 29, 2020 10:20 AM > To: Slurm User Community List <slurm-users@lists.schedmd.com> > Subject: EXTERNAL: Re: [slurm-users] Memory per CPU > > ** This email has been received from outside the organization – Think > before clicking on links, opening attachments, or responding. ** > > what leads you to believe that you're getting 2 CPU's instead of 1? > 'scontrol show job <id>' would be a helpful first start. > > On Tue, Sep 29, 2020 at 9:56 AM Luecht, Jeff A <jeff.lue...@pnc.com> > wrote: > > > > I am working on my first ever SLURM cluster build for use as a resource > manager in a JupyterHub Development environment. I have configured the > cluster for SelectType of ‘select/con_res’ with DefMemPerCPU and > MaxMemPerCPU of 16Gb. The idea is to essentially provide for jobs that run > in a 1 CPU/16Gb chunks. This is a starting point for us. > > > > > > > > What I am seeing is that when users submit jobs and ask for memory only > – in this case, 16Gb, SLURM actually allocates 2 CPUs, not 1 that I would > expect. Is my understanding of how this particular configuration works > incorrect? > > > > > > The contents of this email are the property of PNC. If it was not > addressed to you, you have no legal right to read it. If you think you > received it in error, please notify the sender. Do not forward or copy > without permission of the sender. This message may be considered a > commercial electronic message under Canadian law or this message may > contain an advertisement of a product or service and thus may constitute a > commercial electronic mail message under US law. You may unsubscribe at any > time from receiving commercial electronic messages from PNC at > http://pages.e.pnc.com/globalunsub/ > > PNC, 249 Fifth Avenue, Pittsburgh, PA 15222; pnc.com > > > > > > > The contents of this email are the property of PNC. If it was not > addressed to you, you have no legal right to read it. If you think you > received it in error, please notify the sender. Do not forward or copy > without permission of the sender. This message may be considered a > commercial electronic message under Canadian law or this message may > contain an advertisement of a product or service and thus may constitute a > commercial electronic mail message under US law. You may unsubscribe at any > time from receiving commercial electronic messages from PNC at > http://pages.e.pnc.com/globalunsub/ > PNC, 249 Fifth Avenue, Pittsburgh, PA 15222; pnc.com > > > -- Tom Payerle DIT-ACIGS/Mid-Atlantic Crossroads paye...@umd.edu 5825 University Research Park (301) 405-6135 University of Maryland College Park, MD 20740-3831