If the load average calculation which use sampling to get the run queue value happen to pick the number at this very peak moment, the load average value will be strongly biased for several minutes or dozens of minutes. Unfortunately, on Linux, the load average is considering a thread uninterruptible state to be CPU load while in fact, the CPU is idle and free to do other tasks so you should pay attention to that factor and identify potential cases where the load average is high but the actual contention is low.įinally, there might have situations where the run queue is very high but for a very limited period of time. This is what the load average is designed to show. measuring how many threads are using and competing for the vCPU resources. If multi threaded and CPU bound, it will be detected by both commands, but you have to make sure it is not a legit application or daemon which is loading your machine.Īnother more useful metric is derived from the CPU contention, i.e. What you can do is get the average load for each vCPU during a period of time (mpstat provides that) or the average for all vCPUs combined (vmstat).Įven fully CPU bound, if the hostile CPU consumer is single-threaded, it might not blatantly show up in the latter case because other vCPUs might be idle. There is no such thing as instantaneous 80% busy CPU. Not to mention a single vCPU can only be either 100% idle or 100% busy at any given time. It is then not that simple to define how to compute a CPU load. So, We discussed many ways to check the server load or system load in Ubuntu. It displays the total memory usage, CPU usage, swap usage, load averages, Network, Disk I/O, IRQ, and a list of tasks currently running with their memory and CPU usage. Moreover, cores have often variable clock speed. Here, It shows maximum information in less space. Modern CPUs have multiple cores and often each core supports multiple threads. Check CPU usage, if it is higher than 80% (as example) Do something.
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