Re: [PATCH 14/45] writeback: quit on wrap for .range_cyclic (afs)

[Nick Piggin]

On Wed, Oct 07, 2009 at 11:17:06AM +0100, David Howells wrote:
> Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
> 
> > Convert wbc.range_cyclic to new behavior: when past EOF, abort writeback
> > of the inode, which instructs writeback_single_inode() to delay it for
> > a while if necessary.
> > 
> > It removes one inefficient .range_cyclic IO pattern when writeback_index
> > wraps:
> > 	submit [10000-10100], (wrap), submit [0-100]
> > In which the submitted pages may be consisted of two distant ranges.
> > 
> > It also prevents submitting pointless IO for busy overwriters.
> > 
> > CC: David Howells <dhowells@xxxxxxxxxx>
> > Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> 
> Acked-by: David Howells <dhowells@xxxxxxxxxx>

I don't see why. Then the inode is given less write bandwidth than
those which don't wrap (or wrap on "nice" boundaries).

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