From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:44442) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UBQO2-00044g-Uz for qemu-devel@nongnu.org; Fri, 01 Mar 2013 08:52:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UBQO1-0004Yu-MX for qemu-devel@nongnu.org; Fri, 01 Mar 2013 08:52:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:12680) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UBQO1-0004Yl-Cm for qemu-devel@nongnu.org; Fri, 01 Mar 2013 08:52:33 -0500 Message-ID: <5130B29C.3060301@redhat.com> Date: Fri, 01 Mar 2013 06:52:28 -0700 From: Eric Blake MIME-Version: 1.0 References: <5130ADC0.9070402@dlhnet.de> In-Reply-To: <5130ADC0.9070402@dlhnet.de> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="----enig2FHIGSNMRDTAFVLFPBPFK" Subject: Re: [Qemu-devel] [PATCH] migration: use XBZRLE only after bulk stage List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: Orit Wasserman , "qemu-devel@nongnu.org" , Paolo Bonzini This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2FHIGSNMRDTAFVLFPBPFK Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 03/01/2013 06:31 AM, Peter Lieven wrote: > at the beginning of migration all pages are marked dirty and > in the first round a bulk migration of all pages is performed. >=20 > currently all these pages are copied to the page cache regardless > if there are frequently updated or not. this doesn't make sense > since most of these pages are never transferred again. >=20 > this patch changes the XBZRLE transfer to only be used after > the bulk stage has been completed. that means a page is added > to the page cache the second time it is transferred and XBZRLE > can benefit from the third time of transfer. >=20 > since the page cache is likely smaller than the number of pages > its also likely that in the second round the page is missing in the > cache due to collisions in the bulk phase. >=20 > on the other hand a lot of unneccssary mallocs, memdups and frees s/unneccssary/unnecessary/ > are saved. >=20 > Signed-off-by: Peter Lieven Do you have any benchmark numbers? At any rate, the explanation seems sound, so a benchmark should show this. > --- > arch_init.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) Reviewed-by: Eric Blake --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org ------enig2FHIGSNMRDTAFVLFPBPFK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJRMLKcAAoJEKeha0olJ0NqF5AH/1Wn9ZODHVehcmpdGU309W7+ +RwgfGuZcoFUPWYSxrGZDhm35khjxYYqs4MX1XZnrwnpbi49ux/kTymAU//I5jkN LJyI1FGp0TklXEzpXTy8otqTgxuQDnnfdCnYshE20ecTy5iLckJayPe/ys3L798d 8jwwSEm+NgTUoblMyjZ3XbNDOa2FRn3KklqxwjCe/pBVTk+Y/US4uG7QKll687YS fEmceJlxI6wMLpiiKzYZ9CGupqmXqDr211cZxIhZBt5cb5A77XtPj/EzhbViC9o1 bKIgJYXql4q4wYT+dJI41OalFFdQYkgrxg68zlSC7+CBgyLKwWj90o96FDMZvv8= =C8UR -----END PGP SIGNATURE----- ------enig2FHIGSNMRDTAFVLFPBPFK--