Hi All,
I have a host with 32 physical CPUs (with hyperthreading disabled to make the math easier). How do I determine host level co-stop percentage?
From vCenter:
Using Host Co-Stop Values (ie sum of all cores)
Avg Co-Stop for Host: 4500
Duration of Window: 20000ms
To go from Co-Stop summation to % I do the following:
Avg_Co-Stop * 100 / 20000
=4500*100/2000
=22.5%
Is my host spending on average 22.5% of time in a co-stop state? (Tuning docs say anything above 3 shows CPU contention on the host.)
Looking at pCPU Co-Stop Values (ie core average)
Instead of looking at the summation value for the entire host (which was 4500), I'll now assume each pCPU had an average of 4500/32 = 140.
Avg_Co-Stop * 100 / 20000
= 140 * 100 /2000
= 0.7%
Is my host actually spending only 0.7% of time in a co-stop state?
As you can see this has a huge affect on determining root cause of performance on vSMP boxes.
Thank you for any insight!