Re: measuring shared memory usage on Windows

> Hello,
>
> Shridhar Daithankar and Josh Berkus write on
> http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
>
> shared_memory
>
> """
> There is one way to decide what is best for you. Set a high
> value of this parameter and run the database for typical
> usage. Watch usage of shared memory using ipcs or similar
> tools. A recommended figure would be between 1.2 to 2 times
> peak shared memory usage.
> """
>
> I tried to find a way to do this on windows. Scanning all the
> lines of perfmon memory options, I could not see anithing
> like "shared memory usage".
>
> Googling for "shared memory usage" just drove me to some
> ancient WRONG information that PostgreSQL is not possible on
> Windows because of lacking shared memory. (guess that was for
> Windows 95 or similiar)
>
> So: has anybody a hint how I can check how much shared_memory
> is really used by PostgreSQL on Windows, to fine tune this parameter?
>
> I learned the hard way that just rising it can lead to a hard
> performance loss :)

Not really sure :) We're talking about anonymous mapped memory, and I
don't think perfmon lets you look at that. However, there is no limit to
it as there often is on Unix - you can map up to whatever the virual RAM
size is (2Gb/3Gb dependingo n what boot flag you use, IIRC). You can
monitor it as a part of the total memory useage on the server, but
there's no way to automatically show the difference between them.

//Magnus