[torqueusers] Re: Memory Limits with torque/maui & enforcement

Tom Pierce thpierce at gmail.com
Sat Sep 20 13:44:51 MDT 2008


Åke Sandgren wrote:

On Thu, 2008-09-18 at 13:18 -0600, Josh Butikofer wrote:

>>You may want to use pvmem as opposed to just pmem. Sometimes Linux has a hard time enforcing pmem
>>because of the way it handles virtual memory. In my experience, pvmem behaves more as expected. I
>>would try both out and see which seems to work better in your case.>>


>To be specific the linux kernel does NOT enforce pmem (RLIMIT_RSS,
>ulimit -m) at all. There was pieces of such code in the kernel up to
> 2.4.15 or so when they removed it completely.
>There is still no such code in at least the 2.6 based kernels.



So to have torque manage the memeory needs of a parallel job, I need to use
#PBS -l nodes=2:ppn=4: pvmem=1500m     would require that a node have
4 processors, and that each process needs 1500 megabytes of memory, so
the node would have to have 4*1500 = 6000m or 6 Gb per node BEFORE it
would "qualify" the node as having adequate resources to run. And then
if the node only had 6 Gb of physical memory, the next job would have
to wait for this node to be freed-up.

Is that how torque resource manager works with the memory requirement?
 or does pvmem allow for swap space as well?




-----------------------
Thanks

Tom


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