Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems

Dave Chinner
2013-11-12T23:38:16Z

On Thu, Nov 07, 2013 at 06:13:45AM +1100, Dave Chinner wrote:
> On Wed, Nov 06, 2013 at 02:41:11AM -0800, Christoph Hellwig wrote:
> > On Wed, Nov 06, 2013 at 12:07:22PM +1100, Dave Chinner wrote:
> > > + if (!ag_stride && glob_agcount >= 16 && do_prefetch)
> > > + ag_stride = 15;
> >
> > Shouldn't we have a define for the agcount shared by mkfs and repair, and
> > derive the stride from it?
> >
> > Otherwise looks fine.
>
> Yes, we could.

More complex than it looks - the mkfs calculation in
calc_default_ag_geometry() is based on byte counts and a sliding
scale of shifts and hence the resultant multidisk AG counts are
implicit side effects of the those AG size calculations. Hence to
make use of a common #define for this sort of striding, we'd need to
rewrite calc_default_ag_geometry().

I'll do that in a separate patch series, as it's not directly
related to this initial introduction of the feature to repair.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com