I think that it depends on your kernel and the way the cluster is booted (for instance initrd size). You can check the memory used by kernel in dmesg output - search for the line starting with "Memory:". This is fixed. It may be also good idea to "reserve" some space for cache and buffers - check htop or /proc/meminfo (Slab) this may depend on your OS (filesystem, hardware modules) and if you have a limited set of applications - workload. Size of this part of memory may depend on "node size", number of cores should be good measurement.
cheers, Marcin 2018-01-17 6:03 GMT+01:00 Greg Wickham <greg.wick...@kaust.edu.sa>: > > We’re using cgroups to limit memory of jobs, but in our slurm.conf the > total node memory capacity is currently specified. > > Doing this there could be times when physical memory is over subscribed > (physical allocation per job plus kernel memory requirements) and then > swapping will occur. > > Is there a recommended “kernel overhead” memory (either % or absolute > value) that we should deduct from the total physical memory? > > thanks, > > -greg > > -- > Dr. Greg Wickham > Advanced Computing Infrastructure Team Lead > Advanced Computing Core Laboratory > King Abdullah University of Science and Technology > Building #1, Office #0124 > greg.wick...@kaust.edu.sa +966 544 700 330 > -- > > > ________________________________ > This message and its contents including attachments are intended solely > for the original recipient. If you are not the intended recipient or have > received this message in error, please notify me immediately and delete > this message from your computer system. Any unauthorized use or > distribution is prohibited. Please consider the environment before printing > this email. >
