Hallo, the cpu vs. cores vs. threads issues also confused me at the very beginning. Although, in general, we do not encourage our users to make use of hyperthreading, we have decided to leave it enabled in the BIOS as there are some use cases that are known to benefit from hyperthreading.
I think with NodeName=hpathuri-linux CPUs=8 RealMemory=15833 Sockets=1 CoresPerSocket=4 ThreadsPerCore=2 State=UNKNOWN and SelectTypeParameters=CR_CPU you'll indeed be able to schedule up to 8 tasks on that node as you were expecting. However, you'll also have to check carefully how tasks are then get pinned to the CPUs. For a 2 task job (-n 2) this will probably by default pin both processes to one and the same physical core which may not be what you want. I found the following discussion very helpful: https://bugs.schedmd.com/show_bug.cgi?id=1328 For our test environment which serves as a sandbox for our next cluster system I've ended up with NodeName=DEFAULT CPUs=16 Sockets=2 CoresPerSocket=8 ThreadsPerCore=2 State=UNKNOWN and SelectTypeParameters=CR_Core_Memory This is for compute nodes that have 2 sockets, 2 x 8 core processors with hyperthreading enabled in the BIOS. So I followed the "CPUs=<core_count -- not thread_count>" approach suggested in the discussion above. This will tell Slurm to only schedule the physical cores. With this setting Slurm does also show the total physical core count instead of the thread count and also treats the --mem-per-cpu option as "--mem-per-core" which is in our case what most of our users expect. Best regards Jürgen -- Jürgen Salk Scientific Software & Compute Services (SSCS) Kommunikations- und Informationszentrum (kiz) Universität Ulm Telefon: +49 (0)731 50-22478 Telefax: +49 (0)731 50-22471 * mercan <ahmet.mer...@uhem.itu.edu.tr> [190712 21:52]: > Hi; > > If you want to use the threads as cpus, you should set CR_CPU, instead of > CR_Core. > > Regards; > > Ahmet M. > > > 12.07.2019 21:29 tarihinde mercan yazdı: > > Hi; > > > > You can find the Definitions of Socket, Core, & Thread at: > > > > https://slurm.schedmd.com/mc_support.html > > > > Your status: > > > > CPUs=COREs=Sockets*CoresPerSocket=1*4=4 > > > > Threads=COREs*ThreadsPerCore=4*2=8 > > > > Regards; > > > > Ahmet M. > > > > > > > > 12.07.2019 20:15 tarihinde Hanu Pathuri yazdı: > > > > > > Hi, > > > > > > Here is my node information. I am confused with the terminology > > > w.r.t CPU vs CORE. > > > > > > NodeName=hpathuri-linux CPUs=8 RealMemory=15833 Sockets=1 > > > CoresPerSocket=4 ThreadsPerCore=2 State=UNKNOWN. > > > > > > I am unable to schedule more than 4 tasks without over subscribing > > > even through my configuration looks like this: > > > > > > SchedulerType=sched/backfill > > > > > > #SchedulerPort=7321 > > > > > > SelectType=select/cons_res > > > > > > SelectTypeParameters=CR_Core > > > > > > PreemptMode=suspend,GANG > > > > > > Could help clarify what is going on? > > > > > > I was expecting to schedule 8 tasks. > > > > > > Thanks > > > > > > -- GPG A997BA7A | 87FC DA31 5F00 C885 0DC3 E28F BD0D 4B33 A997 BA7A
