Re: [HACKERS] Safe/Fast I/O ...

On Sun, 12 Apr 1998, Bruce Momjian wrote:

> > As David Gould mentioned, we need to do pre-fetching of data pages
> > somehow.
> >
> > 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.
>
> I found it. It is an fcntl option. From man fcntl:
>
> 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.
>
> Who else supports this?

FreeBSD...

Marc G. Fournier
Systems Administrator @ hub.org
primary: scrappy(at)hub(dot)org secondary: scrappy(at){freebsd|postgresql}.org