What counters not to use

A lot of the time, we assume that some very popular counters would be better to monitor memory performance. However, many times, it leads to something else. This means that these are not an indication of a memory performance issue. If this counter is combined with something else, then it may indicate performance degradation.

In this aspect, don't use two of the most popular counters just to understand whether the memory is under pressure or not:

• Mem.consumed (Consumed Memory)
• Mem.vmmemctl (ballooned memory)

Let me show you what they essentially indicate.

The Mem.consumed counter is the amount of memory consumed by one or all VMs. This is calculated as memory granted minus memory saved by sharing. Now the question is why we should not use this. The reason is that memory allocation will vary dynamically based on the VM's entitlement. It is important that a VM should get whatever it actually demands.

Similarly, Mem.vmmemctl is the amount of ballooned memory. This does not indicate a performance problem as well. However, when it gets combined with host swapping, then it indicates a performance problem.