| From: | Ragnar Kjørstad <postgres(at)ragnark(dot)vestdata(dot)no> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Gaetano Mendola <mendola(at)bigfoot(dot)com>, pgsql-admin(at)postgresql(dot)org |
| Subject: | Re: fsync or fdatasync |
| Date: | 2002-09-10 17:28:18 |
| Message-ID: | 20020910192818.A24188@vestdata.no |
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| Lists: | pgsql-admin |
On Tue, Sep 10, 2002 at 01:17:56PM -0400, Bruce Momjian wrote:
> Ragnar Kjørstad wrote:
> > On Tue, Sep 10, 2002 at 11:40:24AM -0400, Bruce Momjian wrote:
> > > We also use
> > > O_SYNC on open if it is available.
> >
> > Why? That will slow tings down...
>
> Actually, no, we are only O_SYNC'ing the WAL writes and sometimes that
> is faster because you are not writing then fsyncing, you are just
> writing. The fdatasync only is better than O_SYNC when you are doing
> multiple WAL writes before an fdatasync and we normally don't do that.
OK, if it is a single write it makes sense. (But I doubt it makes much
of a difference - the overhead of a system call is almoust nothing
compared to a write to disk...)
--
Ragnar Kjørstad
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