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Implement migration via unix sockets. While you can fake this using
exec and netcat, this involves forking another process and is
generally not very nice. By doing this directly in qemu, we can avoid
the copy through the external nc command. This is useful for
implementations (such as libvirt) that want to do "secure" migration;
we pipe the data on the sending side into the unix socket, libvirt
picks it up, encrypts it, and transports it, and then on the remote
side libvirt decrypts it, dumps it to another unix socket, and
feeds it into qemu.
The implementation is straightforward and looks very similar to
migration-exec.c and migration-tcp.c
Signed-off-by: Chris Lalancette <clalance@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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When we finish migration, there may be pending async io requests
in flight. If we don't flush it before stage3 starting, it might be
the case that the guest loses it.
Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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with.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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provide a monitor command to allow one to set the maximum
downtime he is willing to suffer during migration, in seconds.
"ms", "us", "ns" and "s" are accepted as modifiers.
This parameter will be used by ram_save_live() code to determine
a safe moment to enter stage 3
Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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Currently, we're entering migration's stage 3 when
a treshold of 10 pages remain to be transferred in the system.
This has hurt some users. However, any proposed threshold is
arbitrary by nature, and would only shift the annoyance.
The proposal of this patch is to define a max_downtime variable,
which represents the maximum downtime a migration user is willing
to suffer. Then, based on the bandwidth of last iteration, we
calculate how much data we can transfer in such a window of time.
Whenever we reach that value (or lower), we know is safe to enter
stage3.
This has largely improved the situation for me.
On localhost migrations, where one would expect things to go as
quickly as me running away from the duty of writting software for
windows, a kernel compile was enough to get the migration stuck.
It takes 20 ~ 30 iterations now.
Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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It may happen that the io-handler is still registered. That causes
select() to return with EBADF, not calling handlers for other fds.
The io-handler would be registered when (on the source) the whole state
was written but not yet flushed. For example when using QEMUFileBuffered,
(tcp-migration) there may be data left in a buffer waiting to be transferred.
In such a case buffered_close() calls buffered_flush() which calls
migrate_fd_put_buffer, which may, upon EAGAIN, register migrate_fd_put_notify
as a handler.
Signed-off-by: Uri Lublin <uril@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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This patch allow us to call migrate_set_speed on running
migrations. This should allow mgmt tools to increase the allocated
bandwidth of a running migration if there is no progress, and they
really want the migration to succeed.
Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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This patch augments info migrate output with status about:
* ram bytes remaining
* ram bytes transferred
* ram bytes total
This should be enough for management tools to realize
whether or not there is progress in migration. We can
add more information later on, if the need arrives
[v2: fixes bytes_transferred type]
Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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The migration code is non-blocking, designed for live migration.
Practically migrate_fd_put_buffer busy-loops trying to write, as
on many machines EWOULDBLOCK==EAGAIN (look in include/asm-generic/errno.h).
Signed-off-by: Uri Lublin <uril@redhat.com>
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migrate_fd_put_ready() calls qemu_savevm_state_complete(),
but the later can fail.
If it happens, re-start the vm and propagate the error up
Based on a patch by Yaniv Kamay
Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6997 c046a42c-6fe2-441c-8c8c-71466251a162
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This allows to create monitor terminals that do not make use of the
interactive readline back-end but rather send complete commands. The
pass-through monitor interface of the gdbstub will be an example.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6717 c046a42c-6fe2-441c-8c8c-71466251a162
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Currently all registered (and activate) monitor terminals work in
broadcast mode: Everyone sees what someone else types on some other
terminal and what the monitor reports back. This model is broken when
you have a management monitor terminal that is automatically operated
and some other terminal used for independent guest inspection. Such
additional terminals can be multiplexed device channels or a gdb
frontend connected to QEMU's stub.
Therefore, this patch decouples the buffers and states of all monitor
terminals, allowing the user to operate them independently. It finally
starts to use the 'mon' parameter that was introduced earlier with the
API rework. It also defines the default monitor: the first instantance
that has the MONITOR_IS_DEFAULT flag set, and that is the monitor
created via the "-monitor" command line switch (or "vc" if none is
given).
As the patch requires to rework the monitor suspension interface, it
also takes the freedom to make it "truely" suspending (so far suspending
meant suppressing the prompt, but inputs were still processed).
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6715 c046a42c-6fe2-441c-8c8c-71466251a162
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Refactor the monitor API and prepare it for decoupled terminals:
term_print functions are renamed to monitor_* and all monitor services
gain a new parameter (mon) that will once refer to the monitor instance
the output is supposed to appear on. However, the argument remains
unused for now. All monitor command callbacks are also extended by a mon
parameter so that command handlers are able to pass an appropriate
reference to monitor output services.
For the case that monitor outputs so far happen without clearly
identifiable context, the global variable cur_mon is introduced that
shall once provide a pointer either to the current active monitor (while
processing commands) or to the default one. On the mid or long term,
those use case will be obsoleted so that this variable can be removed
again.
Due to the broad usage of the monitor interface, this patch mostly deals
with converting users of the monitor API. A few of them are already
extended to pass 'mon' from the command handler further down to internal
functions that invoke monitor_printf.
At this chance, monitor-related prototypes are moved from console.h to
a new monitor.h. The same is done for the readline API.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6711 c046a42c-6fe2-441c-8c8c-71466251a162
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KVM's live migration support included support for exec: URLs, allowing system
state to be written or received via an arbitrary popen()ed subprocess. This
provides a convenient way to pipe state through a compression algorithm or an
arbitrary network transport on its way to its destination, and a convenient way
to write state to disk; libvirt's qemu driver currently uses migration to exec:
targets for this latter purpose.
This version of the patch refactors now-common code from migrate-tcp.c into
migrate.c.
Signed-off-by: Charles Duffy <Charles_Duffy@messageone.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5694 c046a42c-6fe2-441c-8c8c-71466251a162
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Replace tabs with spaces.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5527 c046a42c-6fe2-441c-8c8c-71466251a162
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This patch introduces a tcp protocol for live migration. It can be used as
follows:
qemu-system-x86_64 -hda ~/images/linux-test.img -monitor stdio
<vm runs for a while>
(qemu) migrate tcp:localhost:1025
On the same system:
qemu-system-x86_64 -hda ~/images/linux-test.img -incoming
tcp:localhost:1025
The monitor can be interacted with while waiting for an incoming live
migration.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5478 c046a42c-6fe2-441c-8c8c-71466251a162
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This patch introduces a command line parameter and monitor command for starting
a live migration. The next patch will provide an example of how to use these
parameters.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5476 c046a42c-6fe2-441c-8c8c-71466251a162
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