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Re: postgres.exe mem usage in task manager

From: "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>
To: "Magnus Hagander" <mha(at)sollentuna(dot)net>
Cc: <pgsql-hackers-win32(at)postgresql(dot)org>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: postgres.exe mem usage in task manager
Date: 2004-04-16 17:40:14
Message-ID: 6EE64EF3AB31D5448D0007DD34EEB34101ADB7@Herge.rcsinc.local (view raw or flat)
Thread:
Lists: pgsql-hackers-win32
Magnus Hagander wrote:

> Have you checked the "Virtual Memory Size" column? (Not enabled by
> default)
yes.  Virtual memory is 0 or near 0, which is correct.  Otherwise we
really would be double dipping into memory (even if not necessarily
physical memory).  Memory is doled out to each process from the MMF,
which does not belong to any process.  

The virtual memory allocation is in fact somewhere; I have no idea how
to view it from the task manager: I deliberately hacked it down to 128M,
after which the computer alerted me and bumped it up about when you'd
expect. (aside: why do they let you set it if the computer always
overrides you?)

> Microsoft has changed the way task manager reports memory usage
between
> pretty much every windows version (particularly the summary fields)...
> Which version are you on?

XP SP1.  

> Checkpointing is a no-op on win32. sync() does nothing. (OK, not quite
> no-op, it writes a checkpoint record.. But without checkpointing, that
> is actually incorrect).

Well, my observation was based on an apples to apples comparison with
the Interix version which has no sync() either...but WAL, etc. are not
all fsynced(), correct?  My understanding is that with recent versions
of pg that sync plays a less important role.  Checkpointing does do
something; the writer process grinds away for a few seconds, whereas on
Interix it would take 5-10 seconds.  Internal improvements since 7.4.1
may be skewing the results, however.

The upshot is everything appears reliable and quick, even though current
syncing can not be relied on.  I just can't seem to figure out how to
measure server memory consumption in a useful way :(   Interix was much
better in this regard...there you would allocate x megabytes to the
server and you could watch them compete for memory resources.  

Also worth noting that the raw brute insert performance with fsync = off
is about 30% faster than Interix and about 15% faster than cygwin...this
pleases me greatly!

Merlin

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Subject: Re: postgres.exe mem usage in task manager
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