Unfortunately often operating system virtual memory
and filesystem caching code that does exactly the opposite of
what a database application would like.
For some reason the kernel guys don't see it that way ;)
Over the years there have been various kernel features added
with the overall goal of
Performance readers I follow up my promise:I try my theories :)) and contrary to all wisdom from all PostgreSQL
tuning recommendations reconfigured shared memory nearly to theminimum: 1000 for maximum of 400 concurrent connections. (800 would beminimum). Single user performance was fine, now I
Mark,> And THAT is exactly the challenge of this thread: I am searching for
> tools to check shared memory usage on Windows. ipcs is not available.> And neither Magnus nor Dave, both main contributors of the win32 port> of PostgreSQL, and both way wiser concerning Windows internas then me,
> know o
Harald Armin Massa wrote:
Yeah, I know the trial and error method. But I also learned that
reading the manuals and documentation often helps.
So after fastreading the various PostgreSQL tuning materials, I came
accross formulas to calculate a fine starting point for shared memory
size; and the
Magnus,
That shows that you don't really know how the memory manager in NT+
works ;-) *ALL* normal file I/O is handled through the memory manager
:-) So yes, they are both different access methods to the memory
manager, really.
"don't really" is a overstatement, I do not know at all how the m
David,
For example, if you have 1G of RAM on the box, you can't
configure a cache of 900 meg and expect things to work well.
This is because the OS and associated other stuff running on
the box will use ~300megs. The system will page as a result.
Overcommitting of memory leads to trashing, yes
really makes me think that that area is just a comfortable way to
access files on disk as memory areas; with the hope of propably better
caching then not-memory-mapped files.
No, absolutely not. CreateFileMaping() does much the same thing
as mmap() in Unix.
That would explain my disturbing i
I learned the hard way that just rising it can lead to a hard
performance loss :)
I looked back in the list archives to try to find your post on the
underlying problem, but could only find this rather terse sentence.
If you have more detailed information please post or point me at it.
But...m
> > > "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?
> >
> > Hmm. Yeah, most likely :) I may have grabbed that name fro
Magnus,
> "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?
Hmm. Yeah, most likely :) I may have grabbed that name from something
els
> > 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 sur
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 Idon
> 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
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 ipc
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