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envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Sun, Jan 04, 2026 at 01:44:52PM +0800, Zhang Chen wrote: > On Tue, Dec 30, 2025 at 11:02 PM Peter Xu wrote: > > > > On Tue, Dec 30, 2025 at 03:05:43PM +0100, Lukas Straub wrote: > > > Hello everyone, > > > This adds COLO multifd support and migration unit tests for COLO migration > > > and failover. > > > > Hi, Lukas, > > > > I'll review the series after the new year. > > > > Could you still introduce some background on how you're deploying COLO? Do > > you use it in production, or for fun? > > > > COLO is still a nice and interesting feature, said that, COLO has quite a > > lot of code plugged into migration core. I wished it's like a multifd > > compressor which was much more self-contained, but it's not. I wished we > > can simplify the code in QEMU migration. > > > > We've talked it through before with current COLO maintainers, it looks to > > me there aren't really much users using it in production, meanwhile COLO > > doesn't look like a feature to benefit individual QEMU users either. > > > > I want to study the use case of COLO in status quo, and evaluate how much > > effort we should put on it in the future. Note that if it's for fun we can > > always use a stable branch which will be there forever. We'll need to > > think about QEMU evolving in the future, and what's best for QEMU. > > > > Thanks, > > > > Hi Lukas and Peter, Hi, Chen, > > Thanks for this series, I will support for background info if Peter > have any questions. Thanks, I believe my major question so far was, whether we should deprecate COLO in migration framework. :) The netfilters and rest can be discussed separately. Now looking back at my initial ask in Zhijian's fix, I still agree with Zhijian on these two points mentioned: https://lore.kernel.org/all/b2eadde7-57e9-426c-8487-e500ba06410e@fujitsu.com/ That is: - Active users who depend on it. - A unit test for the COLO framework. Meanwhile, I can't see how COLO would win if to be compared with some app-level HA infrastructure.. considering the overhead it requires on running two VMs and compare every packet. Lukas, thanks for trying to fix the 2nd. I apologize that I still requested you to send these patches, without further raising the attention that I still want to discuss deprecation. I don't think anyone yet proved we should keep COLO. I do plan to send one patch adding COLO framework to deprecation, if nobody would stop me in a week justifying question 1 above. We kind of proved almost nobody is actively using COLO anymore in the past few releases. If nobody is using COLO, we should simply drop it. > And CC Hailiang Zhang, although he hasn't replied to emails for a long time. > If no one objects, I think Lukas can replease Hailiang for COLO Framework. > > COLO Framework > M: Hailiang Zhang > S: Maintained > F: migration/colo* > F: include/migration/colo.h > F: include/migration/failover.h > F: docs/COLO-FT.txt Right, this is also another reason why I think we may want to deprecate COLO framework. Since I requested this series (sorry again, Lukas), I'll review it today no matter if we decide to merge this series at last, or deprecate COLO framework. Thanks, > > Thanks > Chen > > > > > > > Regards, > > > Lukas > > > > > > Signed-off-by: Lukas Straub > > > --- > > > Lukas Straub (3): > > > multifd: Add colo support > > > migration-test: Add -snapshot option for COLO > > > migration-test: Add COLO migration unit test > > > > > > migration/meson.build | 2 +- > > > migration/multifd-colo.c | 57 ++++++++++++++++++ > > > migration/multifd-colo.h | 26 +++++++++ > > > migration/multifd.c | 14 ++++- > > > tests/qtest/meson.build | 7 ++- > > > tests/qtest/migration-test.c | 1 + > > > tests/qtest/migration/colo-tests.c | 115 +++++++++++++++++++++++++++++++++++++ > > > tests/qtest/migration/framework.c | 69 +++++++++++++++++++++- > > > tests/qtest/migration/framework.h | 10 ++++ > > > 9 files changed, 294 insertions(+), 7 deletions(-) > > > --- > > > base-commit: 942b0d378a1de9649085ad6db5306d5b8cef3591 > > > change-id: 20251230-colo_unit_test_multifd-8bf58dcebd46 > > > > > > Best regards, > > > -- > > > Lukas Straub > > > > > > > -- > > Peter Xu > > > -- Peter Xu