Process.memory_full_info().swap double counts the swapped size on Linux (Ubuntu 16.04)

[loop-evgeny]

When I get memory_full_info().swap for a .NET Core process on Linux the value reported is double that shown in /proc/PID/status under "VmSwap".

From looking at memory_full_info in _pslinux.py, it seems that the regex "Swap.*:\s+(\d+)" is counting both the "Swap:" and "SwapPss:" lines, which double-counts the same memory usage.

$ uname -a
Linux linuxtest21 4.4.0-1050-aws #59-Ubuntu SMP Tue Jan 30 19:57:10 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

cat /proc/2722/smaps |grep Swap
Swap:                328 kB
SwapPss:             328 kB
Swap:                  8 kB
SwapPss:               8 kB
Swap:                288 kB
SwapPss:             288 kB
Swap:                  8 kB
SwapPss:               8 kB
Swap:                  4 kB
SwapPss:               4 kB
Swap:                  4 kB
SwapPss:               4 kB
Swap:                  4 kB
SwapPss:               4 kB
Swap:                 36 kB
SwapPss:              36 kB
...

Swap and SwapPss each add up to the same value as VmSwap in /proc/PID/status and memory_full_info().swap returns their sum. I'd expect it to return only the sum of the "Swap:" lines, i.e. the same as VmSwap.

[giampaolo]

This should now be fixed.

[giampaolo]

We were also erroneously summing "Pss:" and "SwapPss" together.