Re: [Xen-devel] [PATCH] xen-blkfront: correct maximum segment accounting

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Mon, Jan 23, 2017 at 08:11:37AM -0700, Jan Beulich wrote:
> Making use of "max_indirect_segments=" has issues:
> - blkfront_setup_indirect() may end up with zero psegs when PAGE_SIZE
>   is sufficiently much larger than XEN_PAGE_SIZE
> - the variable driven by the command line option
>   (xen_blkif_max_segments) has a somewhat different purpose, and hence
>   should namely never end up being zero
> - as long as the specified value is lower than the legacy default,
>   we better don't use indirect segments at all (or we'd in fact lower
>   throughput)
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks for catching this, all this PAGE_SIZE != XEN_PAGE_SIZE is quite prone to
errors IMHO.

Roger.

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