| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Sean Chittenden <sean(at)chittenden(dot)org>, "Jim C(dot) Nasby" <jim(at)nasby(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: O_DIRECT in freebsd |
| Date: | 2003-06-23 02:28:44 |
| Message-ID: | 15406.1056335324@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> _That_ is an excellent point. However, do we know at the time we open
> the file descriptor if we will be doing this?
We'd have to say on a per-read basis whether we want O_DIRECT or not,
and fd.c would need to provide a suitable file descriptor.
> What about cache
> coherency problems with other backends not opening with O_DIRECT?
If O_DIRECT introduces cache coherency problems against other processes
not using O_DIRECT then the whole idea is a nonstarter, but I can't
imagine any kernel hackers would have been stupid enough to allow that
to happen ...
regards, tom lane
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