From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36840) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkZRs-00020o-WD for qemu-devel@nongnu.org; Fri, 09 Oct 2015 11:19:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZkZRp-0008DU-ON for qemu-devel@nongnu.org; Fri, 09 Oct 2015 11:19:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36312) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZkZRp-0008DK-HZ for qemu-devel@nongnu.org; Fri, 09 Oct 2015 11:19:05 -0400 Date: Fri, 9 Oct 2015 16:19:01 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20151009151900.GE2702@work-vm> References: <5614531B.5080107@redhat.com> <1444198846-5383-1-git-send-email-den@openvz.org> <1444198846-5383-4-git-send-email-den@openvz.org> <561534A4.1070306@redhat.com> <5616839E.1050909@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5616839E.1050909@openvz.org> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 3/8] migration: add new capability test-only List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Denis V. Lunev" Cc: jsnow@redhat.com, Igor Redko , qemu-devel@nongnu.org, annam@virtuozzo.com * Denis V. Lunev (den@openvz.org) wrote: > On 10/07/2015 06:05 PM, Eric Blake wrote: > >On 10/07/2015 12:20 AM, Denis V. Lunev wrote: > >>From: Igor Redko > >> > >>This patch declares a new migration capability that allows > >>to distinguish between true migration and the test. > >> > >>An alternative is using a custom URI but in this case the > >>following problems should be solved: > >>1/ QEMUFile abstraction hides the real transport type > >>2/ We must be ensured that VM will not be stopped due to > >>=E2=80=9Csuccessful migration=E2=80=9D > >> > >>Possible solutions: > >>1/ Using global variable analogous to > >>s->enabled_capabilities[MIGRATION_CAPABILITY_TEST_ONLY] that > >>will be initialized according to the migration type at the > >>beginning of the migration process > >>2/ Additional hook, presence of implementation of which allows > >>to decide whether the migration is true > >> > >Do we want to name the capability 'x-test-only', since this series is > >experimental, to make it obvious that production code should not rely = on it? > > > actually the answer is 'no'. This feature is designated for production. > May be the name is just wrong or description is bad :) Yep, I know this > for sure... >=20 > OK. The idea of this feature is to estimate efforts required to > perform migration and downtime during that migration. > This estimate is necessary to decide whether we are able > to automatically move the VM from one node (loaded) to > different node with less load. Yes, this is the use we had also been considering. > Should we rename 'test' to 'estimate' or something like that > to make the situation clearer? >=20 > On the other hand this 'estimate' state would be very useful > for testing that is why I have proposed this code to John. > At least we were able to catch recently fixed hang on migration > cancel (in pipeline already). >=20 > I am completely open to any idea. I can see how 'test' might confuse with other test things; but I'm not too fussy about the name. I was thinking 'null' if it was a transport name. Dave >=20 >=20 > >>+++ b/qapi-schema.json > >>@@ -540,11 +540,14 @@ > >> # @auto-converge: If enabled, QEMU will automatically throttle down= the guest > >> # to speed up convergence of RAM migration. (since 1.6) > >> # > >>+# @test-only: If enabled, QEMU instead of migrating will estimate mi= gration > >>+# time basing on given downtime and current dirty page rate > >If we do decide to add this to mainline, it would need 'since 2.5' (or > >whatever version) documentation. > > > Sure! >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK