Creating an event-driven interface for Loadleveler requires two steps.

1. Create and enable the Loadleveler submit filter.
2. Create a suid wrapper to allow global use of the mschedctl -r command.

Step 1: Create a submit filter.

The Loadleveler submit filter functions by taking a user's job command file as STDIN and sending the command file Loadleveler should process to STDOUT. If the submit filter is successful, it should exit with a status of 0. A simple sample script is provided below:

-----------
#!/bin/perl -w
while ()
 {
 $line = $_;
 print STDOUT $line;
 }
# Call wakeup script to moab scheduler
system("/usr/local/sbin/wakeup > /dev/null");
exit(0);
------------

To enable use of this script you must set SUBMITFILTER parameter in the LoadL_config file.

Step 2: Create wrapper

The moab command mschedctl is not normally available to general end users. The wrapper allows users to issue a command to request that scheduling resume to process a newly-submitted job.

A sample wakeup.c wrapper file is included below:

-----
#include 
#include 
#define MOABADMIN    "loadl"
#define SCHEDCTLCMD  /usr/local/bin/mschedctl
int main()
  {
  struct passwd *buf;
  if ((buf = getpwnam(MOABADMIN)) == NULL)
    exit(1);
  setuid(buf->pw_uid);
  system("SCHEDCTLCMD -r 1");
  exit(0);
  }
-----

To enable the wrapper, use the following steps:

• edit 'MOABADMIN' and 'SCHEDCTLCMD' #defines in wakeup.c as needed
• compile code
• make wakeup owned by MOABADMIN - ie, chown loadl wakeup
• make wakeup setuid for owner - ie, chmod 4711 wakeup
• verify non-admin users can successfully run wakeup

   Now submit a job.  If all works correctly, Moab should detect and, if resources are available, start the job within one second.