Improve process memory stats

PsUtil 4+ introdices:

memory_full_info()

This method returns the same information as memory_info(), plus, on some platform (Linux, macOS, Windows), also provides additional metrics (USS, PSS and swap). The additional metrics provide a better representation of “effective” process memory consumption (in case of USS) as explained in detail in this blog post. It does so by passing through the whole process address. As such it usually requires higher user privileges than memory_info() and is considerably slower. On platforms where extra fields are not implemented this simply returns the same metrics as memory_info().

• uss (Linux, macOS, Windows): aka “Unique Set Size”, this is the memory which is unique to a process and which would be freed if the process was terminated right now.

• pss (Linux): aka “Proportional Set Size”, is the amount of memory shared with other processes, accounted in a way that the amount is divided evenly between the processes that share it. I.e. if a process has 10 MBs all to itself and 10 MBs shared with another process its PSS will be 15 MBs.

• swap (Linux): amount of memory that has been swapped out to disk.

Note

uss is probably the most representative metric for determining how much memory is actually being used by a process. It represents the amount of memory that would be freed if the process was terminated right now.

Example on Linux:

import psutil
p = psutil.Process()
p.memory_full_info()
pfullmem(rss=10199040, vms=52133888, shared=3887104, text=2867200, lib=0, data=5967872, dirty=0, uss=6545408, pss=6872064, swap=0)

See also procsmem.py for an example application.

The goal is to study how Glances can use those stats in the processlist plugin.