On Tue, Jun 12, 2007 at 11:32:00AM -0400, Scott Gifford wrote:
> Arnau <arnaulist@andromeiberica.com> writes:
>
> > Hi all,
> >
> > I have a server with 4GB of RAM and I wanted to know how much
> > memory is being used by a PostgreSQL. To do so I have executed the
> > following:
> >
> > ps -A -o rss,vsz,command|grep postgres | awk '{rss += $1; vsz += $2
> > } END { print "Real: ",rss/1024"MB Virtual: ",vsz/1024"MB" }'
> >
> > And the result is:
> > Real: 157.59MB Virtual: 6359.04MB
> >
> > So I understand that amount of virtual memory must be swapped to disk
> > as it's bigger that my physical memory.
>
> Hi Arnau,
>
> Your calculation is incorrect. Many of the PostgreSQL processes are
> sharing the same memory, so while each may be using, for example,
> 500MB of memory, probably 450MB may be the same in each process.
> Memory is shared between parent processes and children and when items
> are mapped into memory with mmap, including the executable and shared
> libraries.
>
> Figuring out exactly how much memory a set of processes are using is a
> difficult problem. Looking in /proc/$pid/maps is a good place to
> start.
>
probably the easiest thing is to use free in two states: with the
process running and without.
if all other factors are the same, then the difference would be the
amount of memory used by the process in question.
or is there something wrong with that?
A
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