I recently attended a practice talk for next week's Partner Exchange hosted by Kit Colbert, one of our senior engineers, who is leading a whole bunch of cool efforts around performance. I wanted to "leak" one slide that his showed us that we'll be touching up for publication. Some of you that are curious about memory counters and want a different take from Memory Performance Analysis and Monitoring may find this interesting.



Some of this stuff won't make sense outside of Kit's presentation, but let me point out a few things that may help consume the information in this incredible chart:

• One of the key messages from Kit's presentation is that ESX reports memory with respect to the guest (the VM) and the host. The very top rectange shows memory stats reported for each VM. The second rectangle shows the single VM's memory stats reported by each host.
• As can be seen from the above, the consumed memory in the host represents everything in the VM, minus the savings due to page sharing.
• This graph doesn't yet highlight the difference between ballooned memory and swapped memory from the guest perspective. From the guest's perspective, swapped memory is much more attractive then ballooned memory, as the guest doesn't know that the swapped memory is gone. But it does see the ballooned memory as pinned. ESX is clever enough to deflate the balloon driver, if possible, when the guest starts to access swapped memory to avoid the host's swapping of guest memory.
• The final rectangle shows memory of all VMs from the host's perspective. Don't pay attention to the reserved and unreserved memory; I'm told those are unnecessary distractions that will be removed.