On Tue, Nov 13, 2012 at 06:16:30PM +0100, Paolo Bonzini wrote: > Il 13/11/2012 18:09, Orit Wasserman ha scritto: > >> > > >>> >> b) do scatter/gather of the pages? > > I would prefer to postpone changing the protocol and start with using iov > > (writev) > > for sending the pages (still sending header and than the page). Later we > > can > > move to scatter/gather I'm not sure of how large the performance gain will > > be. > >> > > >> > c) Remove compression of non-zero repetitive pages. > > +1 > > we can look of identify the zero pages without calling is_dup_page which > > looks > > expensive. > > Identifying ballooned zero pages is useful, because those cause the > clear_page calls in the kernel even in a guest that has been running for > a while. > > But a generic solution doesn't really matter, because is_dup_page and > clear_page shouldn't really be in the profile in practice, except in > microbenchmarks.
I guess mincore(2) can be used as easy way to detect non-mapped page. This is just implementation detail anyway. -- yamahata
