Under /usr/spool/queue you may create several directories for batch jobs, each identified with the class of the batch job (e.g., sas or splus). You may then place restrictions on that class, such as maximum number of jobs running, or total CPU time, by placing a profile file like this one in that directory.

However, the now queue is mandatory; it is the directory used by the -i mode (immediate moe) of queue to launch jobs over the network immediately rather than as batch jobs.

Specify that this queue is turned on:

exec on

The next two lines in profile may be set to an email address rather than a file; the leading / identifies then as file logs. Files now beginning with cf,of, or ef are ignored by the queued:

mail /usr/local/com/queue/now/mail_log
supervisor /usr/local/com/queue/now/mail_log2

Note that /usr/local/com/queue is our spool directory, and now is the job batch directory for the special now queue (run via the -i or immediate-mode flag to the queue executable), so these files may reside in the job batch directories.

The pfactor command is used to control the likelihood of a job being executed on a given machine. Typically, this is done in conjunction with the host command, which specifies that the option on the rest of the line be honored on that host only.

In this example, pfactor is set to the relative MIPS of each machine, for example:

host fast_host pfactor 100
host slow_host pfactor  50

Where fast_host and slow_host are the hostnames of the respective machines.

This is useful for controlling load balancing. Each queue on each machine reports back an `apparant load average' calculated as follows:

1-min load average/ (( max(0, vmaxexec - maxexec) + 1)*pfactor)

The machine with the lowest apparant load average for that queue is the one most likely to get the job.

Consequently, a more powerful pfactor proportionally reduces the load average that is reported back for this queue, indicating a more powerful system.

Vmaxexec is the "apparant maximum" number of jobs allowed to execute in this queue, or simply equal to maxexec if it was not set. The default value of these variables is large value treated by the system as infinity.

host fast_host vmaxexec 2
host slow_host vmaxexec 1
maxexec 3

The purpose of vmaxexec is to make the system appear fully loaded at some point before the maximum number of jobs are already running, so that the likelihood of the machine being used tapers off sharply after vmaxexec slots are filled.

Below vmaxexec jobs, the system aggressively discriminates against hosts already running jobs in this Queue.

In job queues running above vmaxexec jobs, hosts appear more equal to the system, and only the load average and pfactor is used to assign jobs. The theory here is that above vmaxexec jobs, the hosts are fully saturated, and the load average is a better indicator than the simple number of jobs running in a job queue of where to send the next job.

Thus, under lightly-loaded situations, the system routes jobs around hosts already running jobs in this job queue. In more heavily loaded situations, load-averages and pfactors are used in determining where to run jobs.

Additional options in profile

exec

on, off, or drain. Drain drains running jobs.

minfree

disk space on specified device must be at least this free.

maxfree

maximum number of jobs allowed to run in this queue.

loadsched

1 minute load average must be below this value to launch new jobs.

loadstop

if 1 minute load average exceeds this, jobs in this queue are suspended until it drops again.

timesched

Jobs are only scheduled during these times

timestop

Jobs running will be suspended outside of these times

nice

Running jobs are at least at this nice value

rlimitcpu

maximum cpu time by a job in this queue

rlimitdata

maximum data memory size by a job

rlimitstack

maximum stack size

rlimitfsize

maximum fsize

rlimitrss

maximum resident portion size.

rlimitcore

maximum size of core dump

These options, if present, will only override the user's values (via queue) for these limits if they are lower than what the user has set (or larger in the case of nice).