[dm-devel] [PATCH for-dm-3.14-fixes 2/8] dm thin: set flag when over the metadata low watermark threshold
Mike Snitzer
snitzer at redhat.com
Fri Feb 21 14:10:41 UTC 2014
On Fri, Feb 21 2014 at 9:05am -0500,
Mike Snitzer <snitzer at redhat.com> wrote:
> On Fri, Feb 21 2014 at 8:56am -0500,
> Joe Thornber <thornber at redhat.com> wrote:
>
> > NACK
>
> You can NACK all you want. Old code doesn't work. New code does.
>
> > On Thu, Feb 20, 2014 at 09:55:59PM -0500, Mike Snitzer wrote:
> > > The threshold boundary code in persistent-data/dm-space-map-metadata.c
> > > was too racey and resulted in a flood of warnings and events.
> >
> > This code never runs concurrently, so I don't see how it can be racey.
> > Scanning the code it seems to work as advertised; it is an edge
> > triggered threshold, activating every time the free space crosses the
> > threshold from high to low.
> >
> > - You haven't explained what your changes within
> > dm-space-map-metadata.c do. Is the threshold no longer edge
> > triggered?
>
> It is identical to data device's low water mark.
To be clear, it is still edge triggered from the metadata sm -- it makes
the same upcall to t->fn(t->context).
Only difference dm-thin.c:metadata_low_callback controls the throttle on
the event and warning.
More information about the dm-devel
mailing list