patch(es) for htop (open source process viewer for Linux)

This patch adds a

• PSS (proportional set size) field to htop.
• SWAP
• SwapPss

PSS is a newish per-process memory stat in Linux (added in version 2.6.25 of the kernel) that estimates how much memory a process really uses, after taking into account how many other processes share memory with it.

Description on wikipedia

https://en.wikipedia.org/wiki/Proportional_set_size

Article on LWN

https://lwn.net/Articles/230975/

For more info please read description of /proc/PID/smaps file.

https://www.kernel.org/doc/Documentation/filesystems/proc.txt

This problem resolved now.

There's a downside to calculating PSS in htop, and that's that it causes htop to use a lot more CPU. This is because the Linux kernel doesn't provide PSS for each process in a single place but instead requires scanning the entire /proc//smaps file for each process. On my laptop with an Intel Core i3-2350M processor, htop running with the PSS patch consumes about 20% of one CPU. That's with an htop refresh rate (delay) of 1.5 seconds and about 60 processes running. More processes means more CPU use.

When PSS column is hidden, one cycle of LinuxProcessList_recurseProcTree took 20ms, on 181 total tasks (user/kernel threads are disabled).

When PSS column is visible, one cycle of LinuxProcessList_recurseProcTree took 200ms, on 181 total tasks, 10 times slower but not significally.

For ubuntu patched htop available here https://launchpad.net/~linvinus/+archive/ubuntu/linvinus

Other tools that show PSS

smem https://www.2daygeek.com/smem-linux-memory-usage-statistics-reporting-tool/#

libpagemap https://github.com/pholasek/libpagemap

there was a patch based on libpagemap for htop-0.9-3.fc16.src.rpm

https://github.com/dwks/pagemap