[Beowulf] User resource limits

Chris Samuel csamuel at vpac.org
Mon Jun 9 23:56:28 EDT 2008


----- "Prentice Bisbal" <prentice at ias.edu> wrote:

> I think David was assuming I was running Linux, and he was correct.
> thanks for your help. I have to go read some man pages now.

Be very aware that there are two different ulimits that affect
memory allocations, *depending on the size of the allocation that
is asked for*, if you have glibc 2.3 or newer (so most distros
still in use).

For allocations < 128KB the standard memory limit is applied
as it uses brk(), but for allocations greater than that it
uses mmap().

Unfortunately the kernel implementation of mmap() doesn't check
the maximum memory size (RLIMIT_RSS) or maximum data size (RLIMIT_DATA)
limits which were being set, but only the maximum virtual RAM size
(RLIMIT_AS) - this is documented in the setrlimit(2) man page.

:-(

-- 
Christopher Samuel - (03) 9925 4751 - Systems Manager
 The Victorian Partnership for Advanced Computing
 P.O. Box 201, Carlton South, VIC 3053, Australia
VPAC is a not-for-profit Registered Research Agency
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