Hi Rodrigo, good spot. At least, scontrol show job is now saying that each job only requires one "CPU", so it seems all the cores are treated the same way now. Though I still have the problem of not using more than half the cores. So I suppose it might be due to the way I submit (batchtools in this case) the jobs. I'm still investigating even if NumCPUs=1 now as it should be. Thanks.
David On Thu, Oct 8, 2020 at 4:40 PM Rodrigo Santibáñez < rsantibanez.uch...@gmail.com> wrote: > Hi David, > > I had the same problem time ago when configuring my first server. > > Could you try SelectTypeParameters=CR_CPU instead of > SelectTypeParameters=CR_Core? > > Best regards, > Rodrigo. > > On Thu, Oct 8, 2020, 02:16 David Bellot <david.bel...@lifetrading.com.au> > wrote: > >> Hi, >> >> my Slurm cluster has a dozen machines configured as follows: >> >> NodeName=foobar01 CPUs=80 Boards=1 SocketsPerBoard=2 CoresPerSocket=20 >> ThreadsPerCore=2 RealMemory=257243 State=UNKNOWN >> >> and scheduling is: >> >> # SCHEDULING >> SchedulerType=sched/backfill >> SelectType=select/cons_tres >> SelectTypeParameters=CR_Core >> >> My problem is that only half of the logical cores are used when I run a >> computation. >> >> Let me explain: I use R and the package 'batchtools' to create jobs. All >> the jobs are created under the hood with sbatch. If I log in to all the >> machines in my cluster and do a 'htop', I can see that only half of the >> logical cores are used. Other methods to measure the load of each machine >> confirmed this "visual" clue. >> My jobs ask Slurm for only one cpu per task. I tried to enforce that with >> the -c 1 but it didn't make any difference. >> >> Then I realized there was something strange: >> when I do scontrol show job <jobid>, I can spot the following output: >> >> NumNodes=1 NumCPUs=2 NumTasks=0 CPUs/Task=1 ReqB:S:C:T=0:0:*:* >> TRES=cpu=2,node=1,billing=2 >> Socks/Node=* NtasksPerN:B:S:C=0:0:*:2 CoreSpec=* >> >> that is each job uses NumCPUs=2 instead of 1. Also, I'm not sure why >> TRES=cpu=2 >> >> Any idea on how to solve this problem and have 100% of the logical cores >> allocated? >> >> Best regards, >> David >> > -- <https://www.lifetrading.com.au/> David Bellot Head of Quantitative Research A. Suite B, Level 3A, 43-45 East Esplanade, Manly, NSW 2095 E. david.bel...@lifetrading.com.au P. (+61) 0405 263012
