Load indices


Index

Measures

Units

Direction

Averaged over

Update Interval

status

host status

string

15 seconds

r15s

run queue length

processes

increasing

15 seconds

15 seconds

r1m

run queue length

processes

increasing

1 minute

15 seconds

r15m

run queue length

processes

increasing

15 minutes

15 seconds

ut

CPU utilization

percent

increasing

1 minute

15 seconds

pg

paging activity

pages in + pages out per second

increasing

1 minute

15 seconds

ls

logins

users

increasing

N/A

30 seconds

it

idle time

minutes

decreasing

N/A

30 seconds

swp

available swap space

MB

decreasing

N/A

15 seconds

mem

available memory

MB

decreasing

N/A

15 seconds

tmp

available space in temporary file system

MB

decreasing

N/A

120 seconds

io

disk I/O

KB per second

increasing

1 minute

15 seconds

freeslot

available CPU slots

CPU slots

60 seconds


CPU run queue lengths (r15s, r1m, r15m)

The r15s, r1m and r15m load indices are the 15-second, 1-minute and 15-minute average CPU run queue lengths. This is the average number of processes ready to use the CPU during the given interval.

On Linux/UNIX, run queue length indices are not necessarily the same as the load averages printed by the uptime(1) command; uptime load averages on some platforms also include processes that are in short-term wait states (such as paging or disk I/O).

Effective run queue length

On multiprocessor systems, more than one process can execute at a time. The run queue value on multiprocessor systems is scaled to make the CPU load of uniprocessors and multiprocessors comparable. The scaled value is called the effective run queue length.

Normalized run queue length

The CPU run queue length is adjusted based on the relative speeds of the processors (the CPU factor). The normalized run queue length is adjusted for both number of processors and CPU speed. The host with the lowest normalized run queue length runs a CPU-intensive job the fastest.

CPU utilization (ut)

The ut index measures CPU utilization, which is the percentage of time spent running system and user code. A host with no process running has a ut value of 0 percent; a host on which the CPU is completely loaded has a ut of 100 percent.

Paging rate (pg)

The pg index gives the virtual memory paging rate in pages per second. This index is closely tied to the amount of available RAM memory and the total size of the processes running on a host; if there is not enough RAM to satisfy all processes, the paging rate is high. Paging rate is a good measure of how a machine responds to interactive use; a machine that is paging heavily feels very slow.

Login sessions (ls)

The ls index gives the number of users logged in. Each user is counted once, no matter how many times they have logged into the host.

Interactive idle time (it)

On Linux/UNIX, the it index is the interactive idle time of the host, in minutes. Idle time is measured from the last input or output on a directly attached terminal or a network pseudo-terminal supporting a login session. This does not include activity directly through the X server such as CAD applications or emacs windows, except on Solaris and HP-UX systems.

On Windows, the it index is based on the time a screen saver has been active on a particular host.

Temporary directories (tmp)

The tmp index is the space available in MB on the file system that contains the temporary directory:
  • /tmp on Linux/UNIX

  • C:\temp on Windows

Swap space (swp)

The swp index gives the currently available virtual memory (swap space) in MB. This represents the largest process that can be started on the host.

Memory (mem)

The mem index is an estimate of the real memory currently available to user processes. This represents the approximate size of the largest process that could be started on a host without causing the host to start paging.

Free memory is calculated as a sum of physical free memory, cached memory, buffered memory and an adjustment value.

I/O rate (io)

The io index measures I/O throughput to disks attached directly to this host, in KB per second. It does not include I/O to disks that are mounted from other hosts.

Free slots (freeslot)

Current number of available slots for this host across ALL resource groups.