Re: [RFC/PATCH] Nonotify - A simplistic way to determine directory content changes

[Alexander Larsson <alexl redhat com>]

On Sun, 2004-06-06 at 00:33, Danny Milosavljevic wrote:
> Hi,
> 
> Am Thu, den 03.06.2004 um 14:24 Uhr +0200 schrieb nf:
> > On Tue, 2004-06-01 at 12:06, Alexander Larsson wrote: 
> > > On Mon, 2004-05-31 at 20:13, nf wrote:
> > > > I have posted this to the kernel list. Might be interesting for the nautilus 
> > > > developers as well. Perhaps this could be used by "fam" instead of dnotify. 
> > > > Cause i don't see any problems with delivering events from a "polling" mechanism.
> > > > But i don't know if we really need fam in this case, or rather use it from 
> > > > gnome-vfs directly.
> > > 
> > > Not that this might not be a good idea, but your measurements are a bit
> > > skewed. I'm pretty sure that events could be done in a way that uses
> > > less resources (and doesn't block unmount), and what you're measuring is
> > > the worst-case for a notify approach.
> > 
> > When you write a file the regular way (not with "echo's", which
> > open/closes the file for every line), fam/dnotify "only" slows
> > file-writing down by about factor 2. Test-utility attached.
> > 
> > Alexander, another question: Do you think i should continue developing
> > nonotify? I have the feeling that anything less sophisticated than
> > dnotify&events won't get accepted anyway. 
> > 
> > The problem is how to bring the dcontents_mtime timestamp to userspace.
> [...]
> 
> btw, does the mtime timestamp suffice ? What if the file changes, but
> the last time the file was changed was less that half a second ago ?
> Maybe I'm missing something though...

This problem exists with dnotify too. When we get a changed event for
the directory we need to stat for changes anyway. It'll be solved when
we go to higher resolution mtime.

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 Alexander Larsson                                            Red Hat, Inc 
                   alexl redhat com    alla lysator liu se 
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