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Mon, 17 Jun 2024 19:47:59 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id C6x4Cu+ScGbKNQAAD6G6ig (envelope-from ); Mon, 17 Jun 2024 19:47:59 +0000 From: Fabiano Rosas To: Peter Xu , qemu-devel@nongnu.org Cc: Thomas Huth , Markus Armbruster , Laurent Vivier , Eric Blake , Prasad Pandit , peterx@redhat.com, Jiri Denemark , Bandan Das Subject: Re: [PATCH v2 06/10] migration/docs: Update postcopy recover session for SETUP phase In-Reply-To: <20240617181534.1425179-7-peterx@redhat.com> References: <20240617181534.1425179-1-peterx@redhat.com> <20240617181534.1425179-7-peterx@redhat.com> Date: Mon, 17 Jun 2024 16:47:56 -0300 Message-ID: <87frtbbbbn.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[10]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:2; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 Peter Xu writes: > Firstly, the "Paused" state was added in the wrong place before. The state > machine section was describing PostcopyState, rather than MigrationStatus. > Drop the Paused state descriptions. > > Then in the postcopy recover session, add more information on the state > machine for MigrationStatus in the lines. Add the new RECOVER_SETUP phase. > > Signed-off-by: Peter Xu Reviewed-by: Fabiano Rosas > --- > docs/devel/migration/postcopy.rst | 31 ++++++++++++++++--------------- > 1 file changed, 16 insertions(+), 15 deletions(-) > > diff --git a/docs/devel/migration/postcopy.rst b/docs/devel/migration/postcopy.rst > index 6c51e96d79..a15594e11f 100644 > --- a/docs/devel/migration/postcopy.rst > +++ b/docs/devel/migration/postcopy.rst > @@ -99,17 +99,6 @@ ADVISE->DISCARD->LISTEN->RUNNING->END > (although it can't do the cleanup it would do as it > finishes a normal migration). > > - - Paused > - > - Postcopy can run into a paused state (normally on both sides when > - happens), where all threads will be temporarily halted mostly due to > - network errors. When reaching paused state, migration will make sure > - the qemu binary on both sides maintain the data without corrupting > - the VM. To continue the migration, the admin needs to fix the > - migration channel using the QMP command 'migrate-recover' on the > - destination node, then resume the migration using QMP command 'migrate' > - again on source node, with resume=true flag set. > - > - End > > The listen thread can now quit, and perform the cleanup of migration > @@ -221,7 +210,8 @@ paused postcopy migration. > > The recovery phase normally contains a few steps: > > - - When network issue occurs, both QEMU will go into PAUSED state > + - When network issue occurs, both QEMU will go into **POSTCOPY_PAUSED** > + migration state. > > - When the network is recovered (or a new network is provided), the admin > can setup the new channel for migration using QMP command > @@ -229,9 +219,20 @@ The recovery phase normally contains a few steps: > > - On source host, the admin can continue the interrupted postcopy > migration using QMP command 'migrate' with resume=true flag set. > - > - - After the connection is re-established, QEMU will continue the postcopy > - migration on both sides. > + Source QEMU will go into **POSTCOPY_RECOVER_SETUP** state trying to > + re-establish the channels. > + > + - When both sides of QEMU successfully reconnects using a new or fixed up s/reconnects/reconnect I can touch it up when queueing > + channel, they will go into **POSTCOPY_RECOVER** state, some handshake > + procedure will be needed to properly synchronize the VM states between > + the two QEMUs to continue the postcopy migration. For example, there > + can be pages sent right during the window when the network is > + interrupted, then the handshake will guarantee pages lost in-flight > + will be resent again. > + > + - After a proper handshake synchronization, QEMU will continue the > + postcopy migration on both sides and go back to **POSTCOPY_ACTIVE** > + state. Postcopy migration will continue. > > During a paused postcopy migration, the VM can logically still continue > running, and it will not be impacted from any page access to pages that