Re: [Xen-devel] [PATCH 1/6] xenbus: Support HVM backends

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

> >>>Then these 'xenbus_map_ring_valloc' end up just using the
> >>>ring_ops->map call.
> >>
> >>Is the reason for doing this just to avoid overhead? The overhead from
> >>an indirect function call is much higher than from an integer comparison
> >>(which is what xen_pv_domain resolves to). In this case, the _pv and _hvm
> >>functions are both inlined into the dispatch function.
> >
> >Do we care about that? How often are these calls made?
> 
> Not all that often - domain creation and destruction or device plug/unplug.
> So performance doesn't really matter. Is there a reason to prefer an _ops
> structure for this instead of direct calls?

Looks cleaner and fits the bill of where the rest of the Linux kernel is
going with using func structs for most everything.

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