gmirror synchronising is very slow due to frequent metadata updates

[Mark Johnston]

On Thu, Nov 30, 2017 at 03:58:10PM +0100, Andre Albsmeier wrote:
> On Tue, 21-Nov-2017 at 12:38:13 -0500, Mark Johnston wrote:
> > On Mon, Nov 20, 2017 at 06:34:09AM +0100, Andre Albsmeier wrote:
> > > On Sun, 19-Nov-2017 at 22:38:28 -0500, Mark Johnston wrote:
> > > > We should probably decrease the update interval based on the size of a
> > > > mirror. For mirrors larger than say, 1GB, we might just update the
> > > > metadata block once per 1% of the synchronization operation's progress.
> > > 
> > > I think best would be to have it updated every <whatever> seconds.
> > > I think of very fast or very slow drives, or drives which are used
> > > heavily during rebuild (where the effective rebuild speed is quite
> > > low)...
> > 
> > I think that's reasonable. Could you give the patch below a try? It adds
> 
> I am some more weeks in the jungle with nothing more than two
> notebooks so trying your patch will be a bit hard (and, call
> me a coward, I won't do this on my mirror'ed machines 8000 km
> away ;-)).

Fair enough! :)

> 
> Apart from that it looks quite simple and seems to do all what
> we need (my impression as a non-kernel hacker). Maybe someone
> else can review it and we just give it a try?

I tested it myself and committed the change as r326409.