[Beowulf] first cluster  Mark Hahn hahn at mcmaster.ca Thu Jul
15 18:29:59 PDT 2010  >> Disadvantage is of course, when the
system runs out of >> memory the oom-killer will look for an
eligible process >> to be killed to free up some space. > That
assumes that you are permitting your compute nodes > to
overcommit their memory, if you disable overcommit I > believe
that you will instead just get malloc()'s failing > when there
is nothing for them to grab.  sysctl (and the associated
vm.overcommit_ratio.)  every distro I've seen leaves these at
the default seting: vm.overcommit_memory=0.  this  is basically
the traditional setting that tells the kernel to feel free
conserve memory (malloc returning zero), and often kills
processes that where a node may be shared across users/jobs, OOM
can result serious  collateral damage...  we've used
vm.overcommit_memory=2 fairly often.  in this mode, the kernel
limits its VM allocations to a combination of the size of ram
and swap. this is reflected in /proc/meminfo:CommitL