Xi-Batch User Priority Ranges

Xi-BatchXi-Batchpermissionsschedulingbtuchangebtulistbtuser

Every Xi-Batch user has a default priority and a range of priorities they may ask for, and a submission outside that range is refused. This article says what a priority controls, where the range is checked, and how to read and set it.

Priority decides queue order

Every job carries a priority. The priority decides where the job sits in the queue, and so the order in which ready jobs are considered for starting when the load level allows another one to run.

• Priority range: 1 to 255
• Higher number, higher priority
• A job is placed ahead of every queued job with a lower priority and behind those with the same or higher

Priority governs order. A high-priority job still waits where starting it would take the system over its load level.

Each user has three priority settings

They are held in the Xi-Batch user file:

Default priority
Given to a job whose submission does not specify one

Minimum priority
The lowest priority this user may ask for

Maximum priority
The highest priority this user may ask for

Values Xi-Batch ships with:

Default: 150
Minimum: 100
Maximum: 200

These are the values written into the default record when the user file is first created, and every user without an entry of their own runs on them. Changing the default record moves every such user.

The range is checked at submission and at change

The minimum and maximum are checked in two places:

• At submission - btr, bts, the interactive screens and the network interface all validate the priority before the job reaches the queue
• At change - btjchange -p and the priority field in btq apply the same test

A priority outside the range is refused and nothing is queued or changed. The range belongs to the user making the request, so a job may be given a priority its owner could not have asked for, by an administrator whose own range is wider.

# jsmith has minimum 100, maximum 200

btr -p 90 script.sh
# Refused - invalid priority

btr -p 210 script.sh
# Refused - invalid priority

btr -p 150 script.sh
# Queued

btjchange -p 250 15033
# Refused - invalid priority

Two ranges that refuse a submission

Force the user to state a priority

Default: 50   (below the minimum)
Minimum: 100
Maximum: 200

A submission with no -p picks up the default, fails the range test, and is refused with a message telling the user to specify a priority. A submission that names a priority in range succeeds as usual. Setting the default above the maximum has the same effect.

This suits a site where the priority of every job is a deliberate choice.

Stop the user submitting at all

Minimum: 200
Maximum: 100

With the minimum above the maximum no priority can satisfy both, and every submission is refused with a message saying the user cannot use Xi-Batch.

Removing the create entry privilege refuses the submission on its own terms and shows in the privilege column:

btuchange -u -p -CR jsmith

Reading the settings

Your own:

btuser -d

Prints your minimum, maximum and default priorities along with your load levels, privileges and default modes. No privilege is required. Run from a user's own account, it shows the range that user is working under.

All users (requires the read admin file privilege):

# The default listing includes the three priorities
btulist -H

# Just the priorities
btulist -H -F "%u %g %d %l %m"

The format letters are %d default, %l minimum ("lower") and %m maximum. The listing opens with a DEFAULT line giving the settings inherited by users with no entry of their own; -s suppresses it.

User    Group  Defp Minp Maxp
DEFAULT         150  100  200
jsmith  staff   150  100  200
prodops ops     200  180  220

Interactively:

# Read-only, requires read admin file
btuser -v

# Editable, requires write admin file
btuser -i

Setting a user's priorities

Requires: write admin file privilege

Command line:

# One user
btuchange -u -d 175 jsmith

# Whole range at once, several users
btuchange -u -d 200 -l 180 -m 220 prodops nightops

-u takes no value - it means "act on users", and the user names follow the options. Omitting the names applies the change to every user. The three options are -l minimum, -d default and -m maximum, and each takes a value from 1 to 255.

Interactively, in btuser -i:

1. Move to the user with j and k
2. Press l for the minimum, u for the maximum, d for the default
3. Type the value and press Return

The capitals L, U and D edit the same three settings on the DEFAULT line instead.

Changing the default record

# Change the default record only
btuchange -D -d 150 -l 100 -m 200

# Change it and copy the whole default record over every user
btuchange -D -A -d 150 -l 100 -m 200

-D edits the default record and cannot be combined with user names. -A overwrites every user's priorities, load levels, privileges and default modes with the defaults - it is not confined to the priorities. In btuser -i the same operations are a (copy the defaults to the user under the cursor) and A (copy them to every user).

Tiers are a local convention

Xi-Batch enforces the range and attaches no significance to any particular number, so the meaning of a value such as 180 is a site convention that needs writing down. A worked example, with the shipped 100-200 as the middle band:

btuchange -u -d 200 -l 180 -m 220 prodops
btuchange -u -d 150 -l 120 -m 180 appteam
btuchange -u -d 120 -l 100 -m 140 devteam

Overlapping ranges let a user reach into the next tier; disjoint ranges stop them. The only technical consequence is that a job cannot be given a priority its submitter's range excludes.

Listing by priority

Jobs in priority order:

btjlist lists the queue in queue order, which is priority order, so the highest-priority jobs are already at the top. To see the priorities alongside:

btjlist -H -F "%N %p %U %H"

Users whose range reaches high:

btulist -N -s -F "%m %u" | sort -rn

-N drops the header and -s the DEFAULT line, so the sort sees user rows only.

Related articles

All articles · Release notes · Contact support