Install "Slave Monitor for system load average" plugin.
https://wiki.jenkins-ci.org/display/JENKINS/System+Load+Average+Monitor+Plugin
This plugin do not work for IBM AIX slaves.
Sorry I do not found existing jenkins bug. Could be duplicate.

WARNING: Failed to monitor k35aix01 for System Load Average
java.io.IOException: Remote call on k35aix01 failed
at hudson.remoting.Channel.call(Channel.java:672)
at hudson.plugins.systemloadaverage_monitor.SystemLoadAverageMonitor$1.monitor(SystemLoadAverageMonitor.java:47)
at hudson.plugins.systemloadaverage_monitor.SystemLoadAverageMonitor$1.monitor(SystemLoadAverageMonitor.java:42)
at hudson.node_monitors.AbstractNodeMonitorDescriptor$Record.run(AbstractNodeMonitorDescriptor.java:202)
Caused by: java.lang.NoSuchMethodError: java/lang/management/OperatingSystemMXBean.getSystemLoadAverage()D
at hudson.plugins.systemloadaverage_monitor.SystemLoadAverageMonitor$MonitorTask.call(SystemLoadAverageMonitor.java:73)
at hudson.plugins.systemloadaverage_monitor.SystemLoadAverageMonitor$MonitorTask.call(SystemLoadAverageMonitor.java:64)
at hudson.remoting.UserRequest.perform(UserRequest.java:118)
at hudson.remoting.UserRequest.perform(UserRequest.java:48)
at hudson.remoting.Request$2.run(Request.java:326)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:284)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:665)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:690)
at java.lang.Thread.run(Thread.java:810)
Jul 3, 2012 1:26:43 AM hudson.node_monitors.AbstractNodeMonitorDescriptor$Record run