Hey folks 
I recently deployed a NetScaler 12 VPX appliance onto a vSphere 6.5 environment and came across an issue where the appliance seemed to be running at 100% CPU even though it wasn’t doing anything. This didn’t seem right so I did a big of digging and it turns out it is a common issue. Citrix tell us it is expected behaviour as they have disabled CPU yielding for the VPX Appliance. So effectively what is happening is that the NetScaler appliance is taking the whole CPU for itself. Not good!!
We can disable this by running the following command from the NetScaler command line:
set ns vpxparam –cpuyield YES
Or you can enable it in the GUI:
After enabled it I can see a huge reduction straight away in CPU Usage
Before:
After:
You can read more about the issue here:
It seems it locks a core and not a whole CPU. Whilst still not great, and I still set yield to ‘yes’, it’s not thát big a issue.