Re: O_DIRECT in freebsd

Sean Chittenden wrote:
> > > Nor could it ever be a win unless the cache was populated via
> > > O_DIRECT, actually. Big PG cache == 2 extra copies of data, once
> > > in the kernel and once in PG. Doing caching at the kernel level,
> > > however means only one copy of data (for the most part). Only
> > > problem with this being that it's not always that easy or an
> > > option to reconfig a kernel to have a bigger FS cache. That said,
> > > tripple copying a chunk of mem is generally faster than even a
> > > single disk read. If PostgreSQL ever wanted to have a platform
> > > agnostic way of doing efficient caching, it'd likely have to be in
> > > the userland and would require the use of O_DIRECT.
> >
> > Actually, I think of O_DIRECT as platform-dependent.
>
> FreeBSD, IRIX, and AIX, implement it, and ... *smiles with pride*
> looks like Linux does too given the number of security vulnerabilities
> associated with the call. :-]

OK, that's 4 of 15 platforms.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073