We have a VM running RedHat that seems to have very high system (kernel) utilisation compared to our physical servers running the same OS and workload that show normal system time utilisation.
Any ideas?
Thanks in advance.
what virtual manchine software ?
and how you measure the cpu usage?
i have seen some virtualization software report some weird things to the emulated kernel, so the emulated kernel wuld try to make the maths to get a percentage of cpu used and fail
Hi broli thanks for the pointer. We are using ESX 3.5 with the linux VM running RedHat 4 kernel (due to the app requirements).
We have just upped the VM to have 4 vCPUs to match the physical cousins and this has made things better, the run queue is lighter (as you would expect) and the %system is lower but still a bit higher than expected copmpared to the physical boxes.
VMware Tools is installed as well.
We are measuring the CPU usage with the usual suspects top/sar/vmstat/mpstat.
The VM is not waiting on any I/O either.