Re: [PATCH 0/2] Updating ctime and mtime for memory-mapped files [try #4]

Miklos Szeredi
2008-01-15T20:41:00Z

> On Tue, 2008-01-15 at 21:27 +0100, Miklos Szeredi wrote:
> > > 1. Introduction
> > >
> > > This is the fourth version of my solution for the bug #2645:
> > >
> > > http://bugzilla.kernel.org/show_bug.cgi?id=2645
> > >
> > > Changes since the previous version:
> > >
> > > 1) the case of retouching an already-dirty page pointed out
> > > by Miklos Szeredi has been addressed;
> >
> > I'm a bit sceptical, as we've also pointed out, that this is not
> > possible without messing with the page tables.
> >
> > Did you try my test program on the patched kernel?
> >
> > I've refreshed the patch, where we left this issue last time. It
> > should basically have equivalent functionality to your patch, and is a
> > lot simpler. There might be performance issues with it, but it's a
> > good starting point.
>
> It has the same problem as Anton's in that it won't get triggered again
> for an already dirty mapped page.

Yes, it's not better in this respect, than Anton's patch. And it
might be worse performance-wise, since file_update_time() is sure to
be slower, than set_bit(). According to Andrew, this may not actually
matter in practice, but that would have to be benchmarked, I guess.

Miklos