CODEWITHSUNDEEP
memorymemory-managementps
Kurt Peek
Kurt Peek

Reputation: 57411

How to check the (absolute) memory usage of a process?

I have a server process running with pid 24257 and would like to know how much memory it is using (in order to estimate how much resources to allocate for the same process in Kubernetes). According to the man page for ps (https://man7.org/linux/man-pages/man1/ps.1.html), this can be obtained with the %mem output format specifier:

       %mem        %MEM      ratio of the process's resident set size
                             to the physical memory on the machine,
                             expressed as a percentage.  (alias pmem).

If I run this, I get

> ps -p 24257 -o %mem
%MEM
 0.3

I'm not sure I understand this output, because I'm running the process on a MacBook Pro with 64 GB of memory, so I would expect the (Terminal) process to show up in the Activity Monitor as using ~19 GB of memory. However, the Terminal processes running are nowhere near that (they are at most ~900 Mb).

Is there a way I can get the memory usage as an absolute number (in Mb)? Or otherwise, how do I determine the "physical memory on the machine" used for this calculation?

Upvotes: 1

Views: 10151

Answers (1)

Kurt Peek
Kurt Peek

Reputation: 57411

To convert Nate Eldredge's comments to an answer, firstly, the 0.3 output is a percentage, so 0.3% of 64 GB is 192 MB.

Secondly, the rss output should give the resident set size:

       rss         RSS       resident set size, the non-swapped physical
                             memory that a task has used (in kilobytes).
                             (alias rssize, rsz).

Running this command gives

> ps -p 24257 -o %mem,rss
%MEM    RSS
 0.3 209908

The output of ~21 Mb agrees pretty well with the estimate of ~19 Gb derived from the %MEM output.

Upvotes: 5

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