Subject: Re: G98 + Linda Linux Cluster Scheduler

From: uccatvm <[email-masked]>
Date: Wed, 27 Nov 2002 09:00:55 +0000 (GMT)

Hi Daniel,

I have no experience in running G98 in parallel with Linda, but I
encountered the Shmmax Failed problem when running G98 over 2
prcessors with shared memory and when running NWChem in parallel
over different nodes, so I assume it is the same problem.

The Linux kernel has traditionally fairly small limit for the shared
memory segment size (SHMMAX), and this needs to be increased. On my
dual Xeon (with 2 Gb memory) I have set it to 0.5 Gig, while on some
other 2Gb Xeons in our department it is set to 1Gb.

The way to do it permanently is to put (as root) the lines

# Increase max shared memory
kernel.shmmax=536870912

into /etc/sysctl.conf before rebooting.

The temporary solution is

echo 536870912 > /proc/sys/kernel/shmmax

Hope this helps,

Tanja
-- 
  =====================================================================
   Tanja van Mourik                                                
   Royal Society University Research Fellow
   Chemistry Department 
   University College London  phone:  +44 (0)20-7679-4663      
   20 Gordon Street          e-mail: work: [email-masked] 
   London WC1H 0AJ, UK               home: [email-masked]

   http://www.chem.ucl.ac.uk/people/vanmourik/index.html
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