From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
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To: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
Cc: | Kurt Roeckx <Q(at)ping(dot)be>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Background writer process |
Date: | 2003-11-14 00:18:43 |
Message-ID: | 200311140018.hAE0Ih908395@candle.pha.pa.us |
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Lists: | pgsql-hackers |
Jan Wieck wrote:
> That is all right and as said, how often, how much and how forced we do
> the IO can all be configurable and as flexible as people see fit. But
> whether you use sync(), fsync(), fdatasync(), O_SYNC, O_DSYNC or
> posix_fadvise(), somewhere you have to do the write(). And that write
> has to be coordinated with the buffer cache replacement strategy so that
> you write those buffers that are likely to be replaced soon, and don't
> write those that the strategy thinks keeping for longer anyway. Except
> at a checkpoint, then you have to write whatever is dirty.
>
> The patch I posted does this write() in coordination with the strategy
> in a separate background process, so that the regular backends don't
> have to write under normal circumstances (there are some places in DDL
> statements that call BufferSync(), that's exceptions IMHO). Can we agree
> on this general outline? Or do we have any better proposals?
Agreed. Background write() is a win on all all OS's. It is just the
kernel to disk part we will have to have configurable, I think.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
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