Event Driven LL Interface

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

Step 1)  Create a submit filter.

    The LL submit filter functions by taking a users job command file as STDIN and sending the command file LL 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 (<STDIN>)
  {
  $line = $_;
  print STDOUT $line;
  }
 
# Call wakeup script to maui scheduler

system("/usr/local/sbin/wakeup > /dev/null");
 
exit(0);
------------

    1)    create file 'wakeup.c'

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

Step 2)  Create wrapper

    The maui command 'schedctl' 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.

wakeup.c
-----
#include <sys/types.h>
#include <pwd.h>

#define MAUIADMIN        "loadl"
#define SCHEDCTLCMD   /usr/local/bin/schedctl

void main()

{
  struct passwd *buf;

  if ((buf = getpwnam(MAUIADMIN)) == NULL)
    exit(1);

  setuid(buf->pw_uid);

  system("SCHEDCTLCMD -r 1");

  exit(0);
}
-----

    2)    edit 'MAUIADMIN' and 'SCHEDCTLCMD' #defines in 'wakeup.c' as needed

    3)    compile code

    4)    make 'wakeup' owned by MAUIADMIN

                > chown loadl wakeup

    5)    make 'wakeup' setuid for owner

                > chmod 4711 wakeup

    6)    verify non-admin users can successfully run 'wakeup'

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