From: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
---|---|
To: | Merlin Moncure <merlin(dot)moncure(at)rcsonline(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: win32 port --asynchronous I/O and memory |
Date: | 2003-02-03 22:16:35 |
Message-ID: | 3E3EEA43.9FD7442D@Yahoo.com |
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Lists: | pgsql-hackers |
Merlin Moncure wrote:
>
> Just a quick question... are you guys using the C runtime or the win32
> API to do things like file i/o and memory allocation. If you are using
> the win32 api, are you using asynchronous I/O? Generally, how much raw
> win32 code do you expect to write (assumption: as little as possible).
>
> As for memory, what's the general allocation scheme? I have not looked
> at the source much, but I know postgres has a very good memory manager.
> There are a few different ways of going about it. I wrote a database
> backend of sorts a while back and my experience was that you have to
> take certain precautions or you are in danger of thrashing the server,
> which in extreme cases is basically the same as crashing the system.
> Part of the danger is memory allocations for the database sometimes
> compete with the file system caching, causing massive performance
> degradations. MSSQL avoids this because it is very tightly wound with
> the virtual allocation system.
PostgreSQL's memory context system is untouched and uses the standard C
libraries malloc()/free() as in Unix.
As a rule of thumb, we only touched things that needed to be touched
because of missing features or differences in the C libraries.
Jan
--
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