disk devices speed is ugly

Konstantin Belousov kostikbel at gmail.com
Wed Feb 15 08:53:43 UTC 2012

On Wed, Feb 15, 2012 at 12:27:19AM -0600, Adam Vande More wrote:
> On Tue, Feb 14, 2012 at 10:50 PM, Scott Long <scottl at samsco.org> wrote:
> >
> > Any filesystem that uses bread/bwrite/cluster_read are already using the
> > "generic caching subsystem" that you propose.  This includes UDF, CD9660,
> > MSDOS, NTFS, XFS, ReiserFS, EXT2FS, and HPFS, i.e. every local storage
> > filesystem in the tree except for ZFS.  Not all of them implement
> > VOP_GETPAGES/VOP_PUTPAGES, but those are just optimizations for the vnode
> > pager, not requirements for using buffer-cache services on block devices.
> >  As Kostik pointed out in a parallel email, the only thing that was removed
> > from FreeBSD was the userland interface to cached devices via /dev nodes.
> >
> Does this mean the Architecture Handbook page is wrong?:
> http://www.freebsd.org/doc/en/books/arch-handbook/driverbasics-block.html

No, why did you decided that it is wrong ?
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