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Tsirkin" To: Peter Xu Cc: Akihiko Odaki , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Thomas Huth , Yuri Benditovich , eduardo@habkost.net, marcel.apfelbaum@gmail.com, philmd@linaro.org, wangyanan55@huawei.com, dmitry.fleytman@gmail.com, jasowang@redhat.com, sriram.yagnaraman@est.tech, sw@weilnetz.de, qemu-devel@nongnu.org, yan@daynix.com, Fabiano Rosas , devel@lists.libvirt.org Subject: Re: [PATCH v2 4/4] virtio-net: Add support for USO features Message-ID: <20240811025500-mutt-send-email-mst@kernel.org> References: <20240805060544-mutt-send-email-mst@kernel.org> <2b62780c-a6cb-4262-beb5-81d54c14f545@daynix.com> <20240806092822-mutt-send-email-mst@kernel.org> <890f9d0a-3ded-488d-b274-8be9c38b5df3@daynix.com> <20240808065339-mutt-send-email-mst@kernel.org> <274ccd97-a473-4937-a57b-0029a18069c9@daynix.com> <20240808070912-mutt-send-email-mst@kernel.org> <20240808104559-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.144, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=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 Thu, Aug 08, 2024 at 11:25:29AM -0400, Peter Xu wrote: > On Thu, Aug 08, 2024 at 10:47:28AM -0400, Michael S. Tsirkin wrote: > > On Thu, Aug 08, 2024 at 10:15:36AM -0400, Peter Xu wrote: > > > On Thu, Aug 08, 2024 at 07:12:14AM -0400, Michael S. Tsirkin wrote: > > > > This is too big of a hammer. People already use what you call "cross > > > > migrate" and have for years. We are not going to stop developing > > > > features just because someone suddenly became aware of some such bit. > > > > If you care, you will have to work to solve the problem properly - > > > > nacking half baked hacks is the only tool maintainers have to make > > > > people work on hard problems. > > > > > > IMHO this is totally different thing. It's not about proposing a new > > > feature yet so far, it's about how we should fix a breakage first. > > > > > > And that's why I think we should fix it even in the simple way first, then > > > we consider anything more benefitial from perf side without breaking > > > anything, which should be on top of that. > > > > > > Thanks, > > > > As I said, once the quick hack is merged people stop caring. > > IMHO it's not a hack. It's a proper fix to me to disable it by default for > now. > > OTOH, having it ON always even knowing it can break migration is a hack to > me, when we don't have anything else to guard the migration. It's a hack in the sense that it's specific to this option. But hack or not, it's the only way I have to make people work on a full solution. > > Mixing different kernel versions in migration is esoteric enough for > > this not to matter to most people. There's no rush I think, address > > it properly. > > Exactly mixing kernel versions will be tricky to users to identify, but > that's, AFAICT, exactly happening everywhere. We can't urge user to always > use the exact same kernels when we're talking about a VM cluster. That's > why I think allowing migration to work across those kernels matter. > > I will agree there's no rush iff RHEL9 kernel won't backport TAP at all, > otherwise this will trigger between y-stream after people upgrades partial > of the clusters. > > Thanks, > > -- > Peter Xu