From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36483) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cTpBn-00011o-N0 for qemu-devel@nongnu.org; Wed, 18 Jan 2017 07:18:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cTpBj-0008Ez-OX for qemu-devel@nongnu.org; Wed, 18 Jan 2017 07:18:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41932) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cTpBj-0008Dr-Gu for qemu-devel@nongnu.org; Wed, 18 Jan 2017 07:18:03 -0500 Date: Wed, 18 Jan 2017 10:11:31 -0200 From: Marcelo Tosatti Message-ID: <20170118121129.GB13762@amt.cnet> References: <20170108173234.25721-1-ehabkost@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170108173234.25721-1-ehabkost@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 0/2] Allow migration with invtsc if TSC frequency is explicitly set List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: qemu-devel@nongnu.org, Paolo Bonzini , kvm@vger.kernel.org, Haozhong Zhang , "Daniel P. Berrange" , "Michael S. Tsirkin" , Igor Mammedov , libvir-list@redhat.com, Jiri Denemark On Sun, Jan 08, 2017 at 03:32:32PM -0200, Eduardo Habkost wrote: > This series makes QEMU accept migration if tsc-frequency is > explicitly set on configuration. As management software is > required to keep device configuration the same on migration > source or destination, explicit tsc-frequency will ensure that > either: > > * The destination host has a matching TSC frequency; or > * The destination host has TSC scaling available. > > Changelog > ========= > > v2 -> v3: > * Fix build failure ((missing closing braces) > > v1 -> v2: > * v1 series subject was: > * [PATCH 0/4] Allow migration with invtsc if there's no > frequency mismatch > * Removed patches 3/4 and 4/4, that allowed migration > if no explicit tsc-frequency was set. Implementing the check on > post_load or post_init is not enough to make migration abort, > so we will need a more complex solution to implement that > feature. > > Plans for future work > ===================== > > 1) Querying host TSC frequency/scaling capability > ------------------------------------------------- > > I plan to include TSC frequency/scaling information on > query-cpu-model-expansion model="host" in a future series. Then > management software will be able to automatically configure TSC > frequency when invtsc is enabled, instead of requiring the user > to configure it explicitly. While we don't implement that, invtsc > migration will be possible only if the user configures TSC > frequency manually. > > 2) invtsc migration with no explicit TSC frequency > -------------------------------------------------- > > A future series can implement migration when TSC frequency is not > specified explicitly. It will be a bit more complex because it > requires either letting the destination abort the migration, or > sending TSC frequency/scaling information from destination to > source. > > --- > Cc: Marcelo Tosatti > Cc: "Daniel P. Berrange" > Cc: Paolo Bonzini > Cc: kvm@vger.kernel.org > Cc: Haozhong Zhang > Cc: "Michael S. Tsirkin" > Cc: Igor Mammedov > Cc: libvir-list@redhat.com > Cc: Jiri Denemark > > Eduardo Habkost (2): > kvm: Simplify invtsc check > kvm: Allow invtsc migration if tsc-khz is set explicitly > > target/i386/kvm.c | 20 +++++++++++--------- > 1 file changed, 11 insertions(+), 9 deletions(-) > > -- > 2.11.0.259.g40922b1 Looks good to me.