From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38252) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNUgc-0001Sr-Ks for qemu-devel@nongnu.org; Tue, 11 Mar 2014 17:58:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WNUgW-0002HW-B6 for qemu-devel@nongnu.org; Tue, 11 Mar 2014 17:58:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38671) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WNUgW-0002HA-2R for qemu-devel@nongnu.org; Tue, 11 Mar 2014 17:58:04 -0400 Message-ID: <531F86D6.4080204@redhat.com> Date: Tue, 11 Mar 2014 15:57:42 -0600 From: Eric Blake MIME-Version: 1.0 References: <1392713429-18201-1-git-send-email-mrhines@linux.vnet.ibm.com> <1392713429-18201-12-git-send-email-mrhines@linux.vnet.ibm.com> In-Reply-To: <1392713429-18201-12-git-send-email-mrhines@linux.vnet.ibm.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="OIhcsxiUMwuKqH6nmpllQRlWPxjPJeSpT" Subject: Re: [Qemu-devel] [RFC PATCH v2 11/12] mc: introduce new capabilities to control micro-checkpointing List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mrhines@linux.vnet.ibm.com, qemu-devel@nongnu.org Cc: GILR@il.ibm.com, SADEKJ@il.ibm.com, quintela@redhat.com, BIRAN@il.ibm.com, hinesmr@cn.ibm.com, EREZH@il.ibm.com, owasserm@redhat.com, onom@us.ibm.com, junqing.wang@cs2c.com.cn, lig.fnst@cn.fujitsu.com, gokul@us.ibm.com, dbulkow@gmail.com, pbonzini@redhat.com, abali@us.ibm.com, isaku.yamahata@gmail.com, "Michael R. Hines" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --OIhcsxiUMwuKqH6nmpllQRlWPxjPJeSpT Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 02/18/2014 01:50 AM, mrhines@linux.vnet.ibm.com wrote: > From: "Michael R. Hines" >=20 > New capabilities include the use of RDMA acceleration, > use of network buffering, and keepalive support, as documented > in patch #1. >=20 > Signed-off-by: Michael R. Hines > --- > qapi-schema.json | 36 +++++++++++++++++++++++++++++++++++- > 1 file changed, 35 insertions(+), 1 deletion(-) >=20 > +# Only for performance testing. (Since 2.x) > +# > +# @mc-rdma-copy: MC requires creating a local-memory checkpoint before= > +# transmission to the destination. This requires heavy use of= =20 > +# memcpy() which dominates the processor pipeline. This optio= n=20 > +# makes use of *local* RDMA to perform the copy instead of th= e CPU. > +# Enabled by default only if the migration transport is RDMA.= > +# Disabled by default otherwise. (Since 2.x) How does that work? If I query migration capabilities before requesting a migration, what state am I going to read? Is there coupling where I would observe the state of this flag change merely because I did some other action? And if so, then how do I know that explicitly setting this flag won't be undone by similar coupling? It sounds like you are describing a tri-state option (unspecified so default to migration transport, explicitly disabled, explicitly enabled); but that doesn't work for something that only lists boolean capabilities. The only way around that is to have 2 separate capabilities (one on whether to base decision on transport or to honor override, and the other to provide the override value which is ignored when defaulting by transport). > +# > +# @rdma-keepalive: RDMA connections do not timeout by themselves if a = peer > +# has disconnected prematurely or failed. User-level keepalive= s > +# allow the migration to abort cleanly if there is a problem w= ith the > +# destination host. For debugging, this can be problematic as > +# the keepalive may cause the peer to abort prematurely if we = are > +# at a GDB breakpoint, for example. > +# Enabled by default. (Since 2.x) Enabled-by-default is an interesting choice, but I suppose it is okay. > +# > # Since: 1.2 > ## > { 'enum': 'MigrationCapability', > - 'data': ['xbzrle', 'x-rdma-pin-all', 'auto-converge', 'zero-blocks']= } > + 'data': ['xbzrle',=20 > + 'rdma-pin-all',=20 > + 'auto-converge',=20 > + 'zero-blocks', > + 'mc',=20 > + 'mc-net-disable', > + 'mc-rdma-copy', > + 'rdma-keepalive' > + ] } > =20 > ## > # @MigrationCapabilityStatus >=20 --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --OIhcsxiUMwuKqH6nmpllQRlWPxjPJeSpT 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 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJTH4bWAAoJEKeha0olJ0NqSY4H/2DHiARghUi1EPm9PPQ5cxWs zCwP8be2FKfeEr4LHbB88YgWG4WCH08bJBRjVrnF5tvvu6BRo8vo3YS/3TzB8aL9 JF4lC3DP5vIz4S+puz33pBxzmzQvcEXL5mIW+pLvvtV7bOIedBtWhWUJEHO/HvKU jpLGr9JMbkdyZ+PRFodGI8xwp31CCdl76Wq7EfsnNI8A+lraXAK+W+Yf7UlRz4KU wxu5B1MZyHpTxR792cA58X1883FsIxcEK8t+pkRTbO279VDPtjgrCkhWBY7HSU/D 4NB9i5W1oAtJxFn/9K5LqvQAx4K7MWvDbcfeuOqZq1yk8o6sfLuExp1ct8sAWcI= =xOVZ -----END PGP SIGNATURE----- --OIhcsxiUMwuKqH6nmpllQRlWPxjPJeSpT--