Re: [RFC] [PATCH] Relative lazy atime

From: Arjan van de Ven
Date: Sat Aug 05 2006 - 13:24:30 EST


On Sat, 2006-08-05 at 11:58 -0500, Dave Kleikamp wrote:
> 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.

the vfs shouldn't consider it clean, it should consider it "atime-only
dirty".. with that many of the vfs interaction issues ought to go away

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