Contents
What does proc stat mean?
/proc/stat file. All of the numbers reported in this file are aggregates since the system first booted. These numbers identify the amount of time the CPU has spent performing different kinds of work. Time units are in USER_HZ or Jiffies (typically hundredths of a second).
How often is proc stat update?
/proc/[pid]/stat refresh period That values are called utime and stime. In test environment, this file refreshed 1 ~ 2 sec, so I assume this file often updated by system at least 1 sec.
How to understand CPU utilization?
CPU utilization refers to a computer’s usage of processing resources, or the amount of work handled by a CPU. Actual CPU utilization varies depending on the amount and type of managed computing tasks. Certain tasks require heavy CPU time, while others require less because of non-CPU resource requirements.
How do you calculate CPU usage time?
The calculated CPU time that is derived from the reported consumed CPU time divided by the reported available capacity is 50% (45 seconds divided by 90 seconds). The interactive utilization percentage is 17% (15 seconds divided by 90 seconds). The batch utilization percentage is 33% (30 seconds divided by 90 seconds).
How to calculate CPU usage using proc Stat?
It uses /proc/stat to get CPU times and /proc/ /stat to get the process CPU usage. I added top output here, just to compare results and to be sure it’s (about) correct.
Why does / Proc / Stat not match top?
As you can see, CPU utilization reported by /proc/stat and that reported by top does not match. This happened because we didn’t specify the interval for top, it runs with the default sampling interval of 3 seconds. But in case of /proc/stat it was specified to run with sampling interval of 1 second.
What do the numbers mean in / proc / cpuinfo?
The number of “cpuN” lines is equal to the number of CPUs reported on /proc/cpuinfo. The numbers behind the “cpu” lines identify the amount of time the CPU has spent performing different kind of work: Time spent with normal processing in user mode. Time spent with niced processes in user mode. Time spent running in kernel mode.
How to get the percentage of CPU utilization?
The result is equal to multiplying USER_HZ with the number of CPUs on your system and the seconds between the reads. The difference of column 4 (idle) gives us the time spent idle. The sum minus the idle time gives us the total CPU utilization. Divided by the sum we get the percentage of CPU utilization.