devel/migration/postcopy.rst

25 ``migrate_set_capability postcopy-ram on``
43 ``migrate_set_capability postcopy-blocktime on``
45 Postcopy blocktime can be retrieved by query-migrate qmp command.
46 postcopy-blocktime value of qmp command will show overlapped blocking
47 time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
59 -------------
62 ADVISE->DISCARD->LISTEN->RUNNING->END
64  - Advise
74  - Discard
82  - Listen
93  - Running
102  - End
108 ---------------
118 ----------------
126    - Command: 'postcopy listen'
127    - The device state
131    - Command: 'postcopy run'
145 ---------------------
154   ------------------------------------------------------------------------------
156   main -----DISCARD-CMD_PACKAGED ( LISTEN  DEVICE     DEVICE DEVICE RUN )
161   listen thread:                     --- page -- page -- page -- page -- page --
164   ------------------------------------------------------------------------------
166 - On receipt of ``CMD_PACKAGED`` (1)
168    All the data associated with the package - the ( ... ) section in the diagram -
173 - On receipt of 'postcopy listen' - 3 -(i.e. the 1st command in the package)
181 - The last thing in the ``CMD_PACKAGED`` is a 'RUN' command (6)
189 -----------------------
192 where each of the bit to indicate that page is 'dirty' - i.e. needs
202 -----------------
213   - When network issue occurs, both QEMU will go into **POSTCOPY_PAUSED**
216   - When the network is recovered (or a new network is provided), the admin
218     'migrate-recover' on destination node, preparing for a resume.
220   - On source host, the admin can continue the interrupted postcopy
223     re-establish the channels.
225   - When both sides of QEMU successfully reconnect using a new or fixed up
230     interrupted, then the handshake will guarantee pages lost in-flight
233   - After a proper handshake synchronization, QEMU will continue the
250 -----------------------
255   b) The huge-page configuration on the source and destination VMs must be
257   c) Note that ``-mem-path /dev/hugepages``  will fall back to allocating normal
259      Using ``-mem-prealloc`` enforces the allocation using hugepages.
266 ---------------------------
276 The vhost-user code in QEMU supports clients that have Postcopy support,
277 and the ``vhost-user-bridge`` (in ``tests/``) and the DPDK package have changes
285 fault-thread and page requests are made on behalf of the client by QEMU.
293     b) Avoiding the need for QEMU to perform ufd-wake calls after the
296 Retro-fitting postcopy to existing clients is possible:
299      postcopy.  In vhost-user extra messages are added to the existing
307 ------------------------