(obviously, as we’ve learned, adjust these numbers to the number of processor cores your system has). It’s when the 15-minute average goes north of 1.0 and stays there that you need to snap to. Frankly, if your box spikes above 1.0 on the one-minute average, you’re still fine. You should definitely be looking at the five or 15-minute averages. Which average should I be observing? One, five, or 15 minute? If your load average is staying above > 0.70, it’s time to investigate before things get worse.This is valid, of course, for single-processor boxes. The “number of cores = max load” Rule of Thumb: on a multicore system, your load should not exceed the number of cores available.īase on experience, I would say that 0.70 is the common threshold to determine if a system might be overloaded or there might be any kind of I/O problem.On a dual-core box, a load of 2.00 is 100% CPU utilization.On single-processor/single-core systems, load of 1.00 means 100% CPU utilization. It depends on the number of physical CPUs / CPU cores of your server. What constitutes “good” and “bad” load average values? Such circumstances can result in an elevated load average, which does not reflect an actual increase in CPU use (but still gives an idea on how long users have to wait). This, for example, includes processes blocking due to an NFS server failure or to slow media (e.g., USB 1.x storage devices). However, Linux also includes processes in uninterruptible sleep states (usually waiting for disk activity), which can lead to markedly different results if many processes remain blocked in I/O due to a busy or stalled I/O system. Most UNIX systems count only processes in the running (on CPU) or runnable (waiting for CPU) states. What is a blocking process?Ī blocking process is a process that is waiting for something to continue. This average value is calculated as the exponentially damped/weighted moving average of the load number (each process using or waiting for CPU increments the load number by 1) but this is out of the scope of this post. Simply put, this is the number of blocking processes in the run queue averaged over a certain time period. Load averages are the three numbers shown with the uptime and top commands – they look like this: load average: 0.10 (1min), 0.08 (5min), 0.01 (15min) You might be familiar with Linux load averages already.
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