vfs.ffs.rawreadahead

[Igor Sysoev]

On Wed, Sep 03, 2008 at 04:03:59PM +0530, Sujit Karataparambil wrote:

> The VFS was designed to be Object abtraction of the Berkeley Fast File System.
> This has been since an terminology with journalling filesystem to have
> functionality to added on request.

In src/sys/ufs/ffs/ffs_rawread.c I see that rawreadahead is used.
However, I do not understand whether rawreadahead starts a second
parallel ahead disk transaction with supplied userland buffer or not.


--
Igor Sysoev
http://sysoev.ru/en/

> On 9/3/08, Igor Sysoev <is at rambler-co.ru> wrote:
> > Hi,
> >
> > could anyone tell what does vfs.ffs.rawreadahead enable ?
> > As I understand it's used in DIRECTIO code that allows read data
> > directly to an userland buffer bypassing the buffer cache.
> > What I can not understand where the read ahead data can be placed in ?
> >
> >
> > --
> > Igor Sysoev
> > http://sysoev.ru/en/