We are running a online application on a 3-year old server (quadcore Xeon, 4GB RAM, SAN-disks). The server hosts besides the web application a SQL-, FTP-, SFTP, SMTP, and POP-services.
Over the years the number of customers has increased significantly and the server is now pushed to the limits, often reaching 100% CPU over large time frames.
When I monitors the server performance I noticed that Task manager often reports 100% CPU (performance tab) or close to it but System Idle process (process tab) reports something like 30%.
Can the total CPU workload be 100% despite System Idle process having > 0% ? Is my observation correct?
TomTom kindly answered my qestion and gave the following information:
- A task waiting for disc IO will be taken off the CPU until that has been answered by the scheduler.
- Yes, it is possible to hav a100% workload and spend 30% of that in the idle process. Because this does not mean those 30% are wasted.
- What IS possible is that the CPU is 100% busy but in power savings mode becacause of all the
- An example for
waitingcould be: Because it may be waiting for disc IO.
Rephrased question: In the picture below, it shows CPU usage = 100% Why isn't the total CPU usage
100 - 58 = 42?