[mvapich-discuss] How & where to set ulimit ?

[Jonathan Perkins]

On Thu, Sep 25, 2008 at 09:26:00PM +0530, yogeshwar sonawane wrote:
> Hi all,
> 
> I am using mvapich2 on OFED stack. Referring to user guide, i have set
> memlock limit to unlimited in /etc/security/limits.conf &
> /etc/init.d/sshd. ssh service is restarted. Now, if i do a relogin,
> ulimit -a should show unlimited. But it is showing 32Kb only. The
> account used is user account, not root account.
> Am i doing the correct steps ?

Did you use 'ulimit -l unlimited' in the /etc/init.d/sshd file before it
created the sshd daemon?  If so, it seems that you're following the
correct steps.

> 
> I tried to set this command in .bashrc of the user account. But at
> every login, following error comes:-
> -bash: ulimit: max locked memory: cannot modify limit: Operation not permitted
> 
> I tried to set some number, i.e. ulimit -l 4096. This is successful.
> But setting to 4097 is failing.
> Can somebody give me the correct steps & info ?
> 

Is there a hard memlock limit set?  You may want to try setting this as
well to see if this gives you better results.

Which Linux distribution are you using?  I found that with RHEL5 I can
simply set the soft and hard memlock limits in /etc/security/limits.conf
without even touching /etc/init.d/sshd.

> Mainly, i am running HPL. So whether these settings can hamper the
> performance figures ?
> OR what are the optimal settings ?

I'm not sure if there is a such thing as optimal settings for this.  It
depends on how much memory you want to allow user processes to lock
compared to how much is left for the OS to do its work.

> 
> Thanking you,
> Yogeshwar
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-- 
Jonathan Perkins
http://www.cse.ohio-state.edu/~perkinjo