Description
Load average shows how many processes are waiting in the run queue for a system resource (usually a processor). The higher the load average, the more processes are waiting.
Determination
One way to determine whether a machine has high load average is to use an operating system command such as uptime
or top
while the application is running.
uptime
The uptime
output below shows that the load average is 0.40, 0.46, 0.43 over the last 1, 5 and 15 minutes, respectively.
uptime 15:37:27 up 107 days, 2:24, 32 users, load average: 0.40, 0.46, 0.43
top
The top
output shows, among other things, load average, CPU usage percentages and I/O wait (iowait) percentage. The iowait percentage is the percentage of time the CPU is waiting for an I/O to complete. The output below shows a fairly high load average over the past 1 minute (10.40) for the number of CPUs. It also shows that the CPUs are mostly in use (idle=3.0%) and that I/O wait percentage is low (0.4%).
12:49:24 up 113 days, 23:36, 35 users, load average: 10.40, 5.20, 2.30 615 processes: 587 sleeping, 27 running, 1 zombie, 0 stopped CPU states: cpu user nice system irq softirq iowait idle total 61.7% 0.0% 31.4% 0.5% 2.5% 0.4% 3.0% PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND 22523 user1 15 0 1102M 1.1G 18068 R 3.6 14.1 0:24 1 java 22778 user1 15 0 1102M 1.1G 18068 R 2.1 14.1 0:02 1 java 22682 user1 15 0 1102M 1.1G 18068 R 1.4 14.1 0:07 1 java 22698 user1 15 0 1102M 1.1G 18068 R 1.4 14.1 0:10 0 java 19286 user1 15 0 1100M 1.1G 18080 R 0.5 14.1 0:25 0 java
vsd
Another way to determine whether a machine has high load average is to use vsd
to display the load average values contained in a given Geode statistics archive.
LinuxSystemStats
The chart below shows the LinuxSystemStats loadAverage1, loadAverage5 andloadAverage15 values.
Action
Determining that there is high load is one thing. Finding the source of the load is another (whether it be CPU or I/O). Use the output from top
to help determine if the high load is due to CPU or I/O. If the high load is due to CPU, see the Action section of theTroubleshooting CPU document for actions that can help alleviate CPU issues. If the high load is due to I/O wait percentage, then it might be related to disk I/O. See the Apache Geode Documentation for actions that can help alleviate disk issues for persistent regions.