| e6549197 | 18-Sep-2023 |
Stephen Brennan <stephen.s.brennan@oracle.com> |
dump: Add command interface for kdump-raw formats
The QMP dump API represents the dump format as an enumeration. Add three
new enumerators, one for each supported kdump compression, each named
"kdum
dump: Add command interface for kdump-raw formats
The QMP dump API represents the dump format as an enumeration. Add three
new enumerators, one for each supported kdump compression, each named
"kdump-raw-*".
For the HMP command line, rather than adding a new flag corresponding to
each format, it seems more human-friendly to add a single flag "-R" to
switch the kdump formats to "raw" mode. The choice of "-R" also
correlates nicely to the "makedumpfile -R" option, which would serve to
reassemble a flattened vmcore.
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[ Marc-André: replace loff_t with off_t, indent fixes ]
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230918233233.1431858-4-stephen.s.brennan@oracle.com>
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|
| 074dbce5 | 23-Oct-2023 |
Het Gala <het.gala@nutanix.com> |
migration: New migrate and migrate-incoming argument 'channels'
MigrateChannelList allows to connect accross multiple interfaces.
Add MigrateChannelList struct as argument to migration QAPIs.
We pl
migration: New migrate and migrate-incoming argument 'channels'
MigrateChannelList allows to connect accross multiple interfaces.
Add MigrateChannelList struct as argument to migration QAPIs.
We plan to include multiple channels in future, to connnect
multiple interfaces. Hence, we choose 'MigrateChannelList'
as the new argument over 'MigrateChannel' to make migration
QAPIs future proof.
Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
Signed-off-by: Het Gala <het.gala@nutanix.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231023182053.8711-10-farosas@suse.de>
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|
| e034f883 | 23-Oct-2023 |
Het Gala <het.gala@nutanix.com> |
migration: New QAPI type 'MigrateAddress'
This patch introduces well defined MigrateAddress struct
and its related child objects.
The existing argument of 'migrate' and 'migrate-incoming' QAPI
- 'u
migration: New QAPI type 'MigrateAddress'
This patch introduces well defined MigrateAddress struct
and its related child objects.
The existing argument of 'migrate' and 'migrate-incoming' QAPI
- 'uri' is of type string. The current implementation follows
double encoding scheme for fetching migration parameters like
'uri' and this is not an ideal design.
Motive for intoducing struct level design is to prevent double
encoding of QAPI arguments, as Qemu should be able to directly
use the QAPI arguments without any level of encoding.
Note: this commit only adds the type, and actual uses comes
in later commits.
Fabiano fixed for "file" transport.
Suggested-by: Aravind Retnakaran <aravind.retnakaran@nutanix.com>
Signed-off-by: Het Gala <het.gala@nutanix.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231023182053.8711-2-farosas@suse.de>
Message-Id: <20231023182053.8711-3-farosas@suse.de>
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|
| a87e6451 | 25-Oct-2023 |
Steve Sistare <steven.sistare@oracle.com> |
cpr: reboot mode
Add the cpr-reboot migration mode. Usage:
$ qemu-system-$arch -monitor stdio ...
QEMU 8.1.50 monitor - type 'help' for more information
(qemu) migrate_set_capability x-ignore-shar
cpr: reboot mode
Add the cpr-reboot migration mode. Usage:
$ qemu-system-$arch -monitor stdio ...
QEMU 8.1.50 monitor - type 'help' for more information
(qemu) migrate_set_capability x-ignore-shared on
(qemu) migrate_set_parameter mode cpr-reboot
(qemu) migrate -d file:vm.state
(qemu) info status
VM status: paused (postmigrate)
(qemu) quit
$ qemu-system-$arch -monitor stdio -incoming defer ...
QEMU 8.1.50 monitor - type 'help' for more information
(qemu) migrate_set_capability x-ignore-shared on
(qemu) migrate_set_parameter mode cpr-reboot
(qemu) migrate_incoming file:vm.state
(qemu) info status
VM status: running
In this mode, the migrate command saves state to a file, allowing one
to quit qemu, reboot to an updated kernel, and restart an updated version
of qemu. The caller must specify a migration URI that writes to and reads
from a file. Unlike normal mode, the use of certain local storage options
does not block the migration, but the caller must not modify guest block
devices between the quit and restart. To avoid saving guest RAM to the
file, the memory backend must be shared, and the @x-ignore-shared migration
capability must be set. Guest RAM must be non-volatile across reboot, such
as by backing it with a dax device, but this is not enforced. The restarted
qemu arguments must match those used to initially start qemu, plus the
-incoming option.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <1698263069-406971-6-git-send-email-steven.sistare@oracle.com>
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|
| eea1e5c9 | 25-Oct-2023 |
Steve Sistare <steven.sistare@oracle.com> |
migration: mode parameter
Create a mode migration parameter that can be used to select alternate
migration algorithms. The default mode is normal, representing the
current migration algorithm, and
migration: mode parameter
Create a mode migration parameter that can be used to select alternate
migration algorithms. The default mode is normal, representing the
current migration algorithm, and does not need to be explicitly set.
No functional change until a new mode is added, except that the mode is
shown by the 'info migrate' command.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <1698263069-406971-2-git-send-email-steven.sistare@oracle.com>
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|
| 76cb2f24 | 31-Oct-2023 |
Fiona Ebner <f.ebner@proxmox.com> |
mirror: return mirror-specific information upon query
To start out, only actively-synced is returned.
For example, this is useful for jobs that started out in background
mode and switched to active
mirror: return mirror-specific information upon query
To start out, only actively-synced is returned.
For example, this is useful for jobs that started out in background
mode and switched to active mode. Once actively-synced is true, it's
clear that the mode switch has been completed. Note that completion of
the switch might happen much earlier, e.g. if the switch happens
before the job is ready, once all background operations have finished.
It's assumed that whether the disks are actively-synced or not is more
interesting than whether the mode switch completed. That information
can still be added if required in the future.
In presence of an iothread, the actively_synced member is now shared
between the iothread and the main thread, so turn accesses to it
atomic.
Requires to adapt the output for iotest 109.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231031135431.393137-10-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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|
| 701efc9f | 31-Oct-2023 |
Fiona Ebner <f.ebner@proxmox.com> |
qapi/block-core: turn BlockJobInfo into a union
In preparation to additionally return job-type-specific information.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov
qapi/block-core: turn BlockJobInfo into a union
In preparation to additionally return job-type-specific information.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20231031135431.393137-8-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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|
| d67c54d0 | 31-Oct-2023 |
Fiona Ebner <f.ebner@proxmox.com> |
qapi/block-core: use JobType for BlockJobInfo's type
In preparation to turn BlockJobInfo into a union with @type as the
discriminator. That requires it to be an enum. Even without that
requirement,
qapi/block-core: use JobType for BlockJobInfo's type
In preparation to turn BlockJobInfo into a union with @type as the
discriminator. That requires it to be an enum. Even without that
requirement, it's nicer to have an enum instead of a str here.
No functional change is intended.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20231031135431.393137-7-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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|
| 2d400d15 | 31-Oct-2023 |
Fiona Ebner <f.ebner@proxmox.com> |
mirror: implement mirror_change method
which allows switching the @copy-mode from 'background' to
'write-blocking'.
This is useful for management applications, so they can start out in
background m
mirror: implement mirror_change method
which allows switching the @copy-mode from 'background' to
'write-blocking'.
This is useful for management applications, so they can start out in
background mode to avoid limiting guest write speed and switch to
active mode when certain criteria are fulfilled.
In presence of an iothread, the copy_mode member is now shared between
the iothread and the main thread, so turn accesses to it atomic.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231031135431.393137-6-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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|
| 61a3a5a7 | 31-Oct-2023 |
Fiona Ebner <f.ebner@proxmox.com> |
blockjob: introduce block-job-change QMP command
which will allow changing job-type-specific options after job
creation.
In the JobVerbTable, the same allow bits as for set-speed are used,
because
blockjob: introduce block-job-change QMP command
which will allow changing job-type-specific options after job
creation.
In the JobVerbTable, the same allow bits as for set-speed are used,
because set-speed can be considered an existing change command.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20231031135431.393137-2-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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|
| 864128df | 18-Oct-2023 |
Juan Quintela <quintela@redhat.com> |
migration: Deprecate old compression method
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: J
migration: Deprecate old compression method
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231018115513.2163-6-quintela@redhat.com>
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|
| 66db46ca | 18-Oct-2023 |
Juan Quintela <quintela@redhat.com> |
migration: Deprecate block migration
It is obsolete. It is better to use driver-mirror with NBD instead.
CC: Kevin Wolf <kwolf@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Stefan Hajnoczi <s
migration: Deprecate block migration
It is obsolete. It is better to use driver-mirror with NBD instead.
CC: Kevin Wolf <kwolf@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Hanna Czenczek <hreitz@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231018115513.2163-5-quintela@redhat.com>
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|
| 8846b5bf | 18-Oct-2023 |
Juan Quintela <quintela@redhat.com> |
migration: migrate 'blk' command option is deprecated.
Use blocked-mirror with NBD instead.
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by:
migration: migrate 'blk' command option is deprecated.
Use blocked-mirror with NBD instead.
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231018115513.2163-4-quintela@redhat.com>
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|
| 40101f32 | 18-Oct-2023 |
Juan Quintela <quintela@redhat.com> |
migration: migrate 'inc' command option is deprecated.
Use blockdev-mirror with NBD instead.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by:
migration: migrate 'inc' command option is deprecated.
Use blockdev-mirror with NBD instead.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231018115513.2163-3-quintela@redhat.com>
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|
| 0d177cdd | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
docs/s390x/cpu topology: document s390x cpu topology
Add some basic examples for the definition of cpu topology
in s390x.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Co-developed-by: Nina Sc
docs/s390x/cpu topology: document s390x cpu topology
Add some basic examples for the definition of cpu topology
in s390x.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-15-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| 154893a7 | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
qapi/s390x/cpu topology: add query-s390x-cpu-polarization command
The query-s390x-cpu-polarization qmp command returns the current
CPU polarization of the machine.
Signed-off-by: Pierre Morel <pmor
qapi/s390x/cpu topology: add query-s390x-cpu-polarization command
The query-s390x-cpu-polarization qmp command returns the current
CPU polarization of the machine.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-14-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| 1cfe52b7 | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
qapi/s390x/cpu topology: CPU_POLARIZATION_CHANGE QAPI event
When the guest asks to change the polarization this change
is forwarded to the upper layer using QAPI.
The upper layer is supposed to take
qapi/s390x/cpu topology: CPU_POLARIZATION_CHANGE QAPI event
When the guest asks to change the polarization this change
is forwarded to the upper layer using QAPI.
The upper layer is supposed to take according decisions concerning
CPU provisioning.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-13-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| ad2d1afc | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
machine: adding s390 topology to query-cpu-fast
S390x provides two more topology attributes, entitlement and dedication.
Let's add these CPU attributes to the QAPI command query-cpu-fast.
Signed-o
machine: adding s390 topology to query-cpu-fast
S390x provides two more topology attributes, entitlement and dedication.
Let's add these CPU attributes to the QAPI command query-cpu-fast.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-11-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| a457c2ab | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
qapi/s390x/cpu topology: set-cpu-topology qmp command
The modification of the CPU attributes are done through a monitor
command.
It allows to move the core inside the topology tree to optimize
the
qapi/s390x/cpu topology: set-cpu-topology qmp command
The modification of the CPU attributes are done through a monitor
command.
It allows to move the core inside the topology tree to optimize
the cache usage in the case the host's hypervisor previously
moved the CPU.
The same command allows to modify the CPU attributes modifiers
like polarization entitlement and the dedicated attribute to notify
the guest if the host admin modified scheduling or dedication of a vCPU.
With this knowledge the guest has the possibility to optimize the
usage of the vCPUs.
The command has a feature unstable for the moment.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20231016183925.2384704-10-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| f4f54b58 | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
target/s390x/cpu topology: handle STSI(15) and build the SYSIB
On interception of STSI(15.1.x) the System Information Block
(SYSIB) is built from the list of pre-ordered topology entries.
Signed-of
target/s390x/cpu topology: handle STSI(15) and build the SYSIB
On interception of STSI(15.1.x) the System Information Block
(SYSIB) is built from the list of pre-ordered topology entries.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-5-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| 5de1aff2 | 16-Oct-2023 |
Pierre Morel <pmorel@linux.ibm.com> |
CPU topology: extend with s390 specifics
S390 adds two new SMP levels, drawers and books to the CPU
topology.
S390 CPUs have specific topology features like dedication and
entitlement. These indicat
CPU topology: extend with s390 specifics
S390 adds two new SMP levels, drawers and books to the CPU
topology.
S390 CPUs have specific topology features like dedication and
entitlement. These indicate to the guest information on host
vCPU scheduling and help the guest make better scheduling decisions.
Add the new levels to the relevant QAPI structs.
Add all the supported topology levels, dedication and entitlement
as properties to S390 CPUs.
Create machine-common.json so we can later include it in
machine-target.json also.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Co-developed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-3-nsg@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| 3da4aef8 | 16-Oct-2023 |
Nina Schoetterl-Glausch <nsg@linux.ibm.com> |
qapi: machine.json: change docs regarding CPU topology
Clarify roles of different architectures.
Also change things a bit in anticipation of additional members being
added.
Suggested-by: Markus Arm
qapi: machine.json: change docs regarding CPU topology
Clarify roles of different architectures.
Also change things a bit in anticipation of additional members being
added.
Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Message-ID: <20231016183925.2384704-2-nsg@linux.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
[thuth: Updated some comments according to suggestions from Markus]
Signed-off-by: Thomas Huth <thuth@redhat.com>
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|
| 0a59c02b | 09-Oct-2023 |
Markus Armbruster <armbru@redhat.com> |
qapi: Belatedly update CompatPolicy documentation for unstable
Commit 57df0dff1a1 (qapi: Extend -compat to set policy for unstable
interfaces) neglected to update the "Limitation" paragraph to menti
qapi: Belatedly update CompatPolicy documentation for unstable
Commit 57df0dff1a1 (qapi: Extend -compat to set policy for unstable
interfaces) neglected to update the "Limitation" paragraph to mention
feature 'unstable' in addition to feature 'deprecated'. Do that now.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20231009110449.4015601-1-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
show more ...
|
| e4ceec29 | 13-Oct-2023 |
Juan Quintela <quintela@redhat.com> |
migration: Improve json and formatting
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231013104736.31722-2-quintela@redhat.com> |
| 8b239597 | 10-Oct-2023 |
Peter Xu <peterx@redhat.com> |
migration: Allow user to specify available switchover bandwidth
Migration bandwidth is a very important value to live migration. It's
because it's one of the major factors that we'll make decision
migration: Allow user to specify available switchover bandwidth
Migration bandwidth is a very important value to live migration. It's
because it's one of the major factors that we'll make decision on when to
switchover to destination in a precopy process.
This value is currently estimated by QEMU during the whole live migration
process by monitoring how fast we were sending the data. This can be the
most accurate bandwidth if in the ideal world, where we're always feeding
unlimited data to the migration channel, and then it'll be limited to the
bandwidth that is available.
However in reality it may be very different, e.g., over a 10Gbps network we
can see query-migrate showing migration bandwidth of only a few tens of
MB/s just because there are plenty of other things the migration thread
might be doing. For example, the migration thread can be busy scanning
zero pages, or it can be fetching dirty bitmap from other external dirty
sources (like vhost or KVM). It means we may not be pushing data as much
as possible to migration channel, so the bandwidth estimated from "how many
data we sent in the channel" can be dramatically inaccurate sometimes.
With that, the decision to switchover will be affected, by assuming that we
may not be able to switchover at all with such a low bandwidth, but in
reality we can.
The migration may not even converge at all with the downtime specified,
with that wrong estimation of bandwidth, keeping iterations forever with a
low estimation of bandwidth.
The issue is QEMU itself may not be able to avoid those uncertainties on
measuing the real "available migration bandwidth". At least not something
I can think of so far.
One way to fix this is when the user is fully aware of the available
bandwidth, then we can allow the user to help providing an accurate value.
For example, if the user has a dedicated channel of 10Gbps for migration
for this specific VM, the user can specify this bandwidth so QEMU can
always do the calculation based on this fact, trusting the user as long as
specified. It may not be the exact bandwidth when switching over (in which
case qemu will push migration data as fast as possible), but much better
than QEMU trying to wildly guess, especially when very wrong.
A new parameter "avail-switchover-bandwidth" is introduced just for this.
So when the user specified this parameter, instead of trusting the
estimated value from QEMU itself (based on the QEMUFile send speed), it
trusts the user more by using this value to decide when to switchover,
assuming that we'll have such bandwidth available then.
Note that specifying this value will not throttle the bandwidth for
switchover yet, so QEMU will always use the full bandwidth possible for
sending switchover data, assuming that should always be the most important
way to use the network at that time.
This can resolve issues like "unconvergence migration" which is caused by
hilarious low "migration bandwidth" detected for whatever reason.
Reported-by: Zhiyi Guo <zhguo@redhat.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231010221922.40638-1-peterx@redhat.com>
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