Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Wed, 1 Dec 2021 08:57:57 -0800

On 11/29/21 5:27 AM, Jokinen Antti (F4E) wrote:
> On the other hand we managed to improve the remote server performance significantly by updating the kernel plus enabling VT-X on the virtualization software. FYI according to "#sar -d" the average await parameter was ~2000ms before whereas now it's always <30ms. Additionally now the server seems not to struggle under a heavy load anymore and for example in the remote user point of view, all programs are evenly responsive/unresponsive. 

What is "#sar -d"?  "average await" sounds like a disk metric?
Is this related to eg.

https://linux.die.net/man/1/atopsar

I ask because I've run into odd performance regressions with
software running in VMs before, and struggled to understand
what was going on.  So I'm interested in knowing what you
looked at before noticing that the vt-x CPU extension
wasn't being used?

eg. one thing I look for on Linux+QEMU is if the VM process
opens "/dev/kvm".  (and obviously whether "/dev/kvm" exists)

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System