Re: [Xen-devel] [PATCH] introduce grant copy for user land

[Thanos Makatos <thanos.makatos@xxxxxxxxxx>]

> On 11/11/14 12:27, Thanos Makatos wrote:
> >> The arbitrary limitations in number of ops and page alignment should
> >> be removed.  I think both can be removed relatively easily by
> >> consuming page aligned chunks of segments and doign the hypercall
> >> when a batch of ops is filled.
> >
> > Wouldn't this lead to multiple calls to gnttab_batch_copy(), potentially
> hurting performance?
> 
> The incremental benefits of batching diminishes as the batch size increase.

To overcome the page alignment limitation, struct gntdev_grant_copy_segment
will have to contain a set of grant refs instead of just one grant ref,
correct?
 
> We also don't want multi-page allocations in this driver, so the batch size
> should be set accordingly.

Why not?

> The interface should also support grant to grant copies.

To support grant to grant copies, struct gntdev_grant_copy_segment will have
to contain an additional set of grant refs, correct?

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