From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47749) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPFjW-0000dR-55 for qemu-devel@nongnu.org; Mon, 18 Jul 2016 17:05:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bPFjQ-0003KF-8H for qemu-devel@nongnu.org; Mon, 18 Jul 2016 17:05:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43611) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPFjP-0003K9-QJ for qemu-devel@nongnu.org; Mon, 18 Jul 2016 17:05:40 -0400 References: <1468515285-173356-1-git-send-email-imammedo@redhat.com> <1468515285-173356-6-git-send-email-imammedo@redhat.com> From: Eric Blake Message-ID: <578D44A1.3040802@redhat.com> Date: Mon, 18 Jul 2016 15:05:37 -0600 MIME-Version: 1.0 In-Reply-To: <1468515285-173356-6-git-send-email-imammedo@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="bqNk8TNDo61fL8uo2ExM3ccr9cc8UlUlo" Subject: Re: [Qemu-devel] [PATCH v4 05/16] pc: enforce adding CPUs contiguously and removing them in opposit order List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov , qemu-devel@nongnu.org Cc: pkrempa@redhat.com, Bandan Das , ehabkost@redhat.com, eduardo.otubo@profitbricks.com, mst@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --bqNk8TNDo61fL8uo2ExM3ccr9cc8UlUlo From: Eric Blake To: Igor Mammedov , qemu-devel@nongnu.org Cc: pkrempa@redhat.com, Bandan Das , ehabkost@redhat.com, eduardo.otubo@profitbricks.com, mst@redhat.com Message-ID: <578D44A1.3040802@redhat.com> Subject: Re: [Qemu-devel] [PATCH v4 05/16] pc: enforce adding CPUs contiguously and removing them in opposit order References: <1468515285-173356-1-git-send-email-imammedo@redhat.com> <1468515285-173356-6-git-send-email-imammedo@redhat.com> In-Reply-To: <1468515285-173356-6-git-send-email-imammedo@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 07/14/2016 10:54 AM, Igor Mammedov wrote: s/opposit/opposite/ in the subject line, but it's already long. I wonder if you can go shorter, with: pc: enforce CPU add/remove in contiguous order > it will still allow us to use cpu_index as migration instance_id > since when CPUs are added contiguously (from the first to the last) > and removed in opposite order, cpu_index stays stable and it's > reproducable on destination side. s/reproducable/reproducible/ >=20 > Signed-off-by: Igor Mammedov > --- > While there is work in progress to support migration when there are hol= es > in cpu_index range resulting from out-of-order plug or unplug, this pat= ch > is intended as a last resort if no easy, risk-free and elegant solution= > emerges before 2.7 dev cycle ends. I'm not too worried about succeeding only on contiguous ids, as that has been something libvirt has already had to deal with. But I am a bit worried about whether it is easy to introspect whether 2.8 adds a way to hot-plug (or hot-remove) cpus in arbitrary order, with gaps rather than contiguous ids, especially if the interface does not gain any obvious parameters. If we are going to enhance the interface in the future, do we have any plans how to make it easily detectable which version of the interface we are working with (contiguous-only, or full power)? --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --bqNk8TNDo61fL8uo2ExM3ccr9cc8UlUlo Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJXjUShAAoJEKeha0olJ0Nqq70IAJ4s8p7sCK0Iad874gYMqsBE 2vNWYkwdYP1Z9c4+UndATtrffHNe3lYwDNlACRLjSjzBXk7TpuRpZ4u3TGh3LRnx VgLhRsEMZ0rqN4XlHpW/VBLNtb1hBKcrTwY6qBAVP7Hi2KEMedRDQ//JioROGMLR jwUdV1pLhNMLOcBqF25PVNeUwaRuIyKE2+X9bcAVjtje5nlnX7z0ZiQRjW+SjBpp kECAYTns7+FIEyOJdGnegXpOsVRD8jyU3yYE96mpNp56zSiNptn63XZydZPMenFH pY7YCZlYDa36WqGWpQzP/WAG40r5OAu7908U4iv+fj5tbOXzxfcriClB8n2t5Ug= =DmBb -----END PGP SIGNATURE----- --bqNk8TNDo61fL8uo2ExM3ccr9cc8UlUlo--