Re: [Qemu-devel] [PATCH v3 20/29] postcopy: postcopy_notify_shared_wake

[Peter Xu]

On Tue, Mar 06, 2018 at 10:54:18AM +0000, Dr. David Alan Gilbert wrote:

[...]

> > Basically above was what I thought - to record the faulted addresses
> > with specific PostcopyFD when page fault happened, then we may know
> > which page(s) will a PostcopyFD need.  But when with that, we'll
> > possibly need a lock to protect the information (or any other sync
> > method).
> 
> OK, but I think you're suggesting building a whole new data structure to
> know which ones need notifying;  that sounds like a lot of extra
> complexity for not much gain.

Yes we may need a new structure (or just a list of addresses?), and
indeed I have no idea on how that would help us.  I think it depends
on how many useless wakeup we will have, and how expensive is each of
such a wakeup notification.  Again, I think current solution is good
enough as long as we don't see explicit blocker on performance side,
and we can rethink that when really needed.  Thanks,

-- 
Peter Xu