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[188.85.150.151]) by smtp.gmail.com with ESMTPSA id u5-20020a05600c00c500b004047ac770d1sm10078899wmm.8.2023.10.03.12.00.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Oct 2023 12:00:21 -0700 (PDT) From: Juan Quintela To: Peter Xu Cc: Li Zhijian , leobras@redhat.com, qemu-devel@nongnu.org, Fabiano Rosas Subject: Re: [PATCH v2 1/2] migration: Fix rdma migration failed In-Reply-To: (Peter Xu's message of "Tue, 26 Sep 2023 13:04:38 -0400") References: <20230926100103.201564-1-lizhijian@fujitsu.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.3 (gnu/linux) Date: Tue, 03 Oct 2023 21:00:20 +0200 Message-ID: <875y3n5y63.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=170.10.129.124; envelope-from=quintela@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_H4=0.001, RCVD_IN_MSPIKE_WL=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: , Reply-To: quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu wrote: > On Tue, Sep 26, 2023 at 06:01:02PM +0800, Li Zhijian wrote: >> Migration over RDMA failed since >> commit: 294e5a4034 ("multifd: Only flush once each full round of memory") >> with erors: >> qemu-system-x86_64: rdma: Too many requests in this message (3638950032).Bailing. >> >> migration with RDMA is different from tcp. RDMA has its own control >> message, and all traffic between RDMA_CONTROL_REGISTER_REQUEST and >> RDMA_CONTROL_REGISTER_FINISHED should not be disturbed. >> >> find_dirty_block() will be called during RDMA_CONTROL_REGISTER_REQUEST >> and RDMA_CONTROL_REGISTER_FINISHED, it will send a extra traffic( >> RAM_SAVE_FLAG_MULTIFD_FLUSH) to destination and cause migration to fail >> even though multifd is disabled. >> >> This change make migrate_multifd_flush_after_each_section() return true >> when multifd is disabled, that also means RAM_SAVE_FLAG_MULTIFD_FLUSH >> will not be sent to destination any more when multifd is disabled. >> >> Fixes: 294e5a4034 ("multifd: Only flush once each full round of memory") >> CC: Fabiano Rosas >> Signed-off-by: Li Zhijian >> --- >> >> V2: put that check at the entry of migrate_multifd_flush_after_each_section() # Peter > > When seeing this I notice my suggestion wasn't ideal either, as we rely on > both multifd_send_sync_main() and multifd_recv_sync_main() be no-op when > !multifd. > > For the long term, we should not call multifd functions at all, if multifd > is not enabled.. Agreed. Send a different patch that makes this clear. > Reviewed-by: Peter Xu