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Matt_B1
Enthusiast
Enthusiast

High CPU ready on VMs, low CPU usage average on hosts

We are seeing CPU ready values at 500ms or more on almost every VM in our cluster. All VMs are only using 1 vCPU so SMP is not the issue. When looking at esxtop and CPU usage (average in percent), each of the 8 processors in the hosts average 50% usage or less. Why is the CPU usage not higher if the VMs are waiting on CPU cycles as shown in the CPU ready values? I am trying to figure out why the CPU ready values are so high.

Details:

5 hosts (8 CPUs dual-core HP DL585 G2s); ESX 4.0 build 175625; 166 VMs; DRS full auto at priority 3 or higher; 3 resource pools only using shares set to High, Medium, Low for CPU; over 600 vmotions/wk

Please let me know if you need any more info.

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AntonVZhbankov
Immortal
Immortal

500 ms in 20 s period = 2.5%

This is not a problem, and 50% CPU load is not low actually.

According to VMware recommendations CPU Ready less than 5% is not an issue at all, CPU Ready is too high if more than 10%.


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Matt_B1
Enthusiast
Enthusiast

I have several VMs that average 1500 ms CPU ready time or more. I was highlighting that most or all are 500ms or higher. If the CPU ready is reaching 2000ms or more on some VMs, why am I not seeing CPU usage averages almost 75% or more on the hosts? I did find one interesting point on the CPU usage average for the hosts. On 4 of the 5 hosts in this cluster, each one has one processor that is running at 100% while the rest are around 40% each. Can anyone help me understand this?

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