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

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 13 Nov 2013 10:38:07 +1100
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20131106191345.GD6188@dastard>
References: <1383700043-32305-1-git-send-email-david@xxxxxxxxxxxxx> <1383700043-32305-37-git-send-email-david@xxxxxxxxxxxxx> <20131106104111.GB21067@xxxxxxxxxxxxx> <20131106191345.GD6188@dastard>
User-agent: Mutt/1.5.21 (2010-09-15)
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@xxxxxxxxxxxxx

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