If I have a CPU with 8 cores, is it okay to have a consistent average load of 2.5? Or should it always remain below 1, irrespective of the number of processors / cores?
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Yes. There is no specific load average that is okay or not okay, and because the load average measures I/O as well as CPU usage, the number of cores is basically irrelevant. If the system is performing acceptably, then it's acceptable. If not, not.
David Schwartz
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Let me cite from my training's documentation. This will answer your question.
The load average is displayed using three different sets of numbers, as shown in the following example:
The last piece of information is the average load of the system. Assuming our system is a single-CPU system, the 0.25 means that for the past minute, on average, the system has been 25% utilized. 0.12 in the next position means that over the past 5 minutes, on average, the system has been 12% utilized; and 0.15 in the final position means that over the past 15 minutes, on average, the system has been 15% utilized. If we saw a value of 1.00 in the second position, that would imply that the single-CPU system was 100% utilized, on average, over the past 5 minutes; this is good if we want to fully use a system. A value over 1.00 for a single-CPU system implies that the system was over-utilized: there were more processes needing CPU than CPU was available.
If we had more than one CPU, say a quad-CPU system, we would divide the load average numbers by the number of CPUs. In this case, for example, seeing a 1 minute load average of 4.00 implies that the system as a whole was 100% (4.00/4) utilized during the last minute.
Short term increases are usually not a problem. A high peak you see is likely a burst of activity, not a new level. For example, at start up, many processes start and then activity settles down. If a high peak is seen in the 5 and 15 minute load averages, it would may be cause for concern.
Ely
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