Re: [RFC] [PATCH] Relative lazy atime

[Dave Kleikamp <shaggy@austin.ibm.com>]

On Sat, 2006-08-05 at 14:25 +0200, Christoph Hellwig wrote:
> On Wed, Aug 02, 2006 at 11:36:22PM -0700, Valerie Henson wrote:
> > (Corrected Chris Wedgwood's name and email.)
> > 
> > My friend Akkana followed my advice to use noatime on one of her
> > machines, but discovered that mutt was unusable because it always
> > thought that new messages had arrived since the last time it had
> > checked a folder (mbox format).  I thought this was a bummer, so I
> > wrote a "relative lazy atime" patch which only updates the atime if
> > the old atime was less than the ctime or mtime.  This is not the same
> > as the lazy atime patch of yore[1], which maintained a list of inodes
> > with dirty atimes and wrote them out on unmount.
> 
> Another idea, similar to how atime updates work in xfs currently might
> be interesting:  Always update atime in core, but don't start a
> transaction just for it - instead only flush it when you'd do it anyway,
> that is another transaction or evicting the inode.

Hmm.  That adds a cost to evicting what the vfs considers a clean inode.
It seems wrong, but if that's what xfs does, it must not be a problem.

Shaggy
-- 
David Kleikamp
IBM Linux Technology Center