Re: measuring shared memory usage on Windows

Magnus,

> 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.

thanks for the clarification. However,

"anonymous mapped memory" site:microsoft.com

turns out 0 (zero) results. And even splitting it up there seems to be
nearly no information ... is the same thing by any chance also known by
different names?

> However, there is no limit to it as there often is on Unix - you can map
up to whatever the virtual 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.

So the "performance shock" with high shared memory gets obvious: memory
mapped files get swapped to disk. I assume that swapping is nearly
transparent for the application, leading to a nice trashing ...

I'll keep on searching...

Harald

--
GHUM Harald Massa
persuadere et programmare
Harald Armin Massa
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