The ESX page-sharing statistics.
"shared": the amount of guest physical memory that is being shared.
"common": the amount of machine memory that is common across World(s).
"saving": the amount of machine memory that is saved due to page-sharing.
The monitor maps guest physical memory to machine memory. VMKernel selects to map guest physical pages with the same content to the same machine page. In other words, those guest physical pages are sharing the same machine page. This kind of sharing can happen within the same VM or among the VMs.
Since each VM's "shared" memory measures guest physical memory, the host's "shared" memory may be larger than the total amount of machine memory if memory is overcommitted. "saving" illustrates the effectiveness of page sharing for saving machine memory.
"shared" = "common" + "saving".
Note that esxtop only shows the pshare stats for VMs, excluding the pshare stats for user worlds.
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