From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40683) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dFfIo-0007nP-Mr for qemu-devel@nongnu.org; Tue, 30 May 2017 07:27:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dFfIk-0006i7-M2 for qemu-devel@nongnu.org; Tue, 30 May 2017 07:27:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45308) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dFfIk-0006hj-FW for qemu-devel@nongnu.org; Tue, 30 May 2017 07:27:02 -0400 Date: Tue, 30 May 2017 12:26:56 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170530112655.GH2120@work-vm> References: <1494595886-30912-1-git-send-email-a.perevalov@samsung.com> <1494595886-30912-6-git-send-email-a.perevalov@samsung.com> <43617b5a-0fcc-d171-aa19-4a24a4007e35@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43617b5a-0fcc-d171-aa19-4a24a4007e35@redhat.com> Subject: Re: [Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: Alexey Perevalov , qemu-devel@nongnu.org, i.maximets@samsung.com, peterx@redhat.com * Eric Blake (eblake@redhat.com) wrote: > On 05/12/2017 08:31 AM, Alexey Perevalov wrote: > > Right now it could be used on destination side to > > enable vCPU blocktime calculation for postcopy live migration. > > vCPU blocktime - it's time since vCPU thread was put into > > interruptible sleep, till memory page was copied and thread awake. > > > > Signed-off-by: Alexey Perevalov > > --- > > include/migration/migration.h | 1 + > > migration/migration.c | 9 +++++++++ > > qapi-schema.json | 5 ++++- > > 3 files changed, 14 insertions(+), 1 deletion(-) > > > > > +++ b/qapi-schema.json > > @@ -894,11 +894,14 @@ > > # @release-ram: if enabled, qemu will free the migrated ram pages on the source > > # during postcopy-ram migration. (since 2.9) > > # > > +# @postcopy-blocktime: Calculate downtime for postcopy live migration (since 2.10) > > +# > > # Since: 1.2 > > ## > > { 'enum': 'MigrationCapability', > > 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks', > > - 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] } > > + 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram', > > + 'postcopy-blocktime'] } > > Why does this need to be a capability that we have to turn on, and not > something that is collected unconditionally? Is there a drawback to > having the stat collection always enabled without a capability? Yes, there was a reasonable CPU/memory overhead. (Although it might be lower now). Dave > -- > Eric Blake, Principal Software Engineer > Red Hat, Inc. +1-919-301-3266 > Virtualization: qemu.org | libvirt.org > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK