Disk IO and run queue length

[Salman Ahmed Qureshi]

Hi,
If a process is waiting for disk IO con complete, is it added to the run queue length? For example, if on a 2 CPU machine, if there are two processes are waiting for CPU and 2 are waiting for IO to complete before asking from the CPU tipe, would run queue length be 4 in this case? or Run queue lenght is calculate only on the bases of the processes waiting for the CPU?
Thanks

[DeafFrog]

V. Salom ,
On HP-UX 11i, this does not include processes/threads that are waiting for IO to complete, i.e., high-priority sleepers. On previous versions of HP-UX, the Load Average included hi-priority sleepers , and as such the Average load shown might not be accurate.
Regards,
TheFrogIsDeaf.

[Salman Ahmed Qureshi]

Any idea about AIX? It on a 4 CPU machine, it shows me load average of 7 but CPU usage is around 80%

[muruganantham raju]

Hi,
The processes waiting for IO will not accounted for CPU RUN QUEUE calculation. The process is mainly blocked for disk activity and not for CPU.

In AIX, how many physical processors are there in the system? If it is 4, then you might have enable multithreading in which case the total processors are 8. Load average of 7 is not accounting for 100% CPU utilization.

HTH
Muru