| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: O_DIRECT use |
| Date: | 2002-01-04 21:31:40 |
| Message-ID: | 200201042131.g04LVes26851@candle.pha.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > I have added this item to TODO:
> > * Consider use of open/fctl(O_DIRECT) to minimize OS caching
>
> Why exactly would we wish to minimize OS caching?
>
> In my mind, Postgres has always relied heavily on the existence of a
> layer of kernel caching. Disabling that will hurt far more than help.
Not sure. Someone on IRC brought it up. If we are sequential scanning a
large table, caching may be bad because we are pushing out stuff already
in the cache that may be useful. It is related to this TODO item:
* Add free-behind capability for large sequential scans (Bruce)
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Tom Lane | 2002-01-04 21:47:10 | Re: O_DIRECT use |
| Previous Message | Tom Lane | 2002-01-04 21:29:51 | Re: O_DIRECT use |