Load indices
Use the following predefined load indices to measure the availability of resources.
| 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 | Not applicable | 30 seconds |
| it | idle time | minutes | decreasing | Not applicable | 30 seconds |
| swp | available swap space | MB | decreasing | Not applicable | 15 seconds |
| mem | available memory | MB | decreasing | Not applicable | 15 seconds |
| tmp | available space in temporary file system | MB | decreasing | Not applicable | 120 seconds |
| io | disk I/O | KB per second | increasing | 1 minute | 15 seconds |
| freeslot | available CPU slots | CPU slots | Not applicable | Not applicable | 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®, 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).
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.
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 who are logged in. Each user is counted once, no matter how many times they have logged in to the host.
Interactive idle time (it)
On Linux, 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 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)
- /tmp on Linux
- 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.
Input and output rate (io)
The io index measures input and output throughput to disks attached directly to this host, in KB per second. It does not include input and output to disks that are mounted from other hosts.
Free slots (freeslot)
The current number of available slots for this host across all resource groups.