Re: [PATCH 1/7] KVM: Add a route layer to convert MSI message to GSI

[Sheng Yang <sheng@linux.intel.com>]

On Sunday 11 January 2009 17:38:22 Avi Kivity wrote:
> Sheng Yang wrote:
> > After reconsidering, I must say I prefer add/remove ioctls.
> >
> > About the code size, I don't think it would increase much. I've rewritten
> > the code twice, I think I know the difference is little.
> >
> :( sorry about that.
> :
> > For the option 2 route table ioctl, we got a array from userspace, and
> > would convert it to linked list and keep it in kernel. That's a kind of
> > must(I don't think you would prefer use a array in kernel), and it's very
> > direct.
>
> Actually, eventually we'd want an array indexed by gsi.  Each element
> would be a pointer to another array (one or two routing entries).
>
> Certainly we don't want to iterate a list which could hold several
> hundred interrupts for a large guest.
>
> It's okay to start with a linked list, but eventually we'll want
> something faster.

Oh, I see. What I means here is allocate/deallocate would cause some memory 
fragments, but seems not that critical here.
>
> > So, we have to insert/delete route entry for both. What's the real
> > difference we do it one by one or do it all at once. I don't think it is
> > much different on the code size. And it's indeed very clear and direct.
> >
> > Beside this, option 2 seems strange. Why should we handle this table in
> > this way when it won't result in significant code reduce. Insert/delete
> > entry it there, look up entry is also there, not many things changed. And
> > it's not that direct as option 1, which also can be a source of bugs.
> >
> > How do you think?
>
> I'm not convinced.  Please post your latest, and I will post a
> counter-proposal.

OK.

-- 
regards
Yang, Sheng