Re: Understanding Postgres Memory Usage

On Thu, Aug 25, 2016 at 1:25 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Hmm. I find it mighty suspicious that the USS, PSS, and RSS numbers are
> all increasing to pretty much the same tune, ie from very little to circa
> 100MB. I think there is a decent chance that smem is not doing what it
> says on the tin, and in fact is including shared memory consumption in
> "USS". In which case the apparent leak just corresponds to the process
> gradually touching more and more of the shared buffer arena. (If your
> shared_buffers settings is not somewhere near 100MB, then this theory
> breaks down.)

I can't speak to every implementation of smem, but I have used it
quite a bit under SLES and Ubuntu, and it always seemed to do what
it says -- USS is unshared (process-local) memory and PSS is that
plus the process's portion of shared memory. (The sum of
differences between PSS and USS == total shared memory.) RSS has
the usual meaning.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company