Why don the CPU states sum up to 100%?
Because the CPU plugin does not collect the CPU usage in percent, but rather in “jiffies”. A jiffy is the time-unit which the scheduler in the operating systems uses to manage run times of applications. Under Linux, the default configuration is to have 100 jiffies per second, which leads many users to believe they’re getting a percentage. You can, however, configure your kernel at compile time to use 250 or 1000 jiffies per second, usually resulting in a more responsive system but IO-throughput is decreased. Especially on busy systems, virtual systems and systems with a “tickless kernel” there may not always be the exact number of intended jiffies in one second, resulting in the variance you’ve notice in the graphs. By the way, that you see this issue in collectd but not in other similar tools is due to the fact that collectd collects data much more frequently.
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