From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
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To: | maillist(at)candle(dot)pha(dot)pa(dot)us (Bruce Momjian) |
Cc: | winter(at)jurai(dot)net, scrappy(at)hub(dot)org, pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] Safe/Fast I/O ... |
Date: | 1998-04-12 14:22:42 |
Message-ID: | 199804121422.KAA22778@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
> When doing a sequential scan on a table, the OS is doing a one-page
> prefetch, which is probably enough. The problem is index scans of the
> table. Those are not sequential in the main heap table (unless it is
> clustered on the index), so a prefetch would help here a lot.
>
> That is where we need async i/o. I am looking in BSDI, and I don't see
> any way to do async i/o. The only way I can think of doing it is via
> threads.
O_ASYNC Enable the SIGIO signal to be sent to the process group when
I/O is possible, e.g., upon availability of data to be read.
Now I am questioning this. I am not sure this acually for file i/o, or
only tty i/o.
--
Bruce Momjian | 830 Blythe Avenue
maillist(at)candle(dot)pha(dot)pa(dot)us | Drexel Hill, Pennsylvania 19026
+ If your life is a hard drive, | (610) 353-9879(w)
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