> > for our app only on FreeBSD, Windows, Solaris, and Linux, AFAIK.
>
> Direct IO is a good idea, it prevents applications that are basically
> doing a cache walk from blowing out all your cache.
exactly
> Take for instance anything that either keeps its own cache (postgresql)
> or something that would completely never reuse its cache, like
> cp/dd.

like copying image from CD

> If you want to check out performance of your app on FreeBSD give the
> open(2) syscall a flag of O_DIRECT and let me know how it changes
> your numbers. :)