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Subject: Re: [OMPI users] mem lock limit & ulimit
From: Ralph Castain (rhc_at_[hidden])
Date: 2010-08-18 15:08:00


ulimit basically states that a normal user can increase a specific limit up to the maximum specified by root, either via system limit settings or during configuration of the OS.

So the 256 limit you are seeing is one set locally. I would suggest asking your sys admin for a higher limit if you require one.

On Aug 18, 2010, at 12:17 PM, stabeek wrote:

> Hello,
> I've done a good bit of reading and still cannot get my mpirun programs to execute without giving warnings about the memory lock limit not being "unlimited".
> I'm on an infiniband-(openib)-networked cluster under slurm resource mgmt using openmpi.
> Initially I did not want to set max memlock to unlimited because of security concerns, so I concentrated on having slurm negate this limit via its PropagateResourceLimitsExcept=MEMLOCK setting.
> There was little success with this, and then on reading the MPI FAQ @openmpi for a second time, and seeing that openmpi's source code actually recurs to libc's getrlimit() to ascertain the memlock limit, I decided this setting was not-relevant for me. This is hunch as yet, it would be nice to get it verified, though it won't help me resolve the problem really.
> Now I'm faced with having to ask about ulimit on a mailing which is not about ulimit, but I'm hoping for some people's experience here:
> "ulimit -l unlimited" works if:
> 1) the /etc/security/limits.conf file has unlimited soft and hard limits.
> 2) if you are root.
> These conditions solve the problem. But the 2nd is not feasible as should be clear. The problem is that for a normal user running ulimit does not allow a memlock max setting above 256. Its behaviour is one of:
> "Let normaluser increase max memlock only up to 256"
> Can anybody shed any light or make any suggestions, it would be appreciated. Many thanks.
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