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Add public APIs for post-copy migration 

To use post-copy one has to start the migration with
VIR_MIGRATE_POSTCOPY flag and, while migration is in progress, call
virDomainMigrateStartPostCopy() to switch from pre-copy to post-copy.

Signed-off-by: Cristian Klein <cristiklein@gmail.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
This commit is contained in:
Cristian Klein 2014-12-01 16:59:53 +01:00 committed by Jiri Denemark
parent 5a9cbc6265
commit 1a1246ec7d
7 changed files with 165 additions and 9 deletions

4
include/libvirt/libvirt-domain.h
View File

@ -678,6 +678,7 @@ typedef enum {
VIR_MIGRATE_ABORT_ON_ERROR = (1 << 12), /* abort migration on I/O errors happened during migration */
VIR_MIGRATE_AUTO_CONVERGE = (1 << 13), /* force convergence */
VIR_MIGRATE_RDMA_PIN_ALL = (1 << 14), /* RDMA memory pinning */
VIR_MIGRATE_POSTCOPY = (1 << 15), /* enable (but do not start) post-copy migration */
} virDomainMigrateFlags;
@ -836,6 +837,9 @@ int virDomainMigrateGetMaxSpeed(virDomainPtr domain,
unsigned long *bandwidth,
unsigned int flags);
int virDomainMigrateStartPostCopy(virDomainPtr domain,
unsigned int flags);
char * virConnectGetDomainCapabilities(virConnectPtr conn,
const char *emulatorbin,
const char *arch,

5
src/driver-hypervisor.h
View File

@ -637,6 +637,10 @@ typedef int
unsigned long resource,
const char *dom_xml);
typedef int
(*virDrvDomainMigrateStartPostCopy)(virDomainPtr domain,
unsigned int flags);
typedef int
(*virDrvConnectIsEncrypted)(virConnectPtr conn);
@ -1455,6 +1459,7 @@ struct _virHypervisorDriver {
virDrvDomainSetUserPassword domainSetUserPassword;
virDrvConnectRegisterCloseCallback connectRegisterCloseCallback;
virDrvConnectUnregisterCloseCallback connectUnregisterCloseCallback;
virDrvDomainMigrateStartPostCopy domainMigrateStartPostCopy;
};

141
src/libvirt-domain.c
View File

@ -3537,6 +3537,7 @@ virDomainMigrateUnmanaged(virDomainPtr domain,
* automatically when supported).
* VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe.
* VIR_MIGRATE_OFFLINE Migrate offline
* VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy
*
* VIR_MIGRATE_TUNNELLED requires that VIR_MIGRATE_PEER2PEER be set.
* Applications using the VIR_MIGRATE_PEER2PEER flag will probably
@ -3573,6 +3574,11 @@ virDomainMigrateUnmanaged(virDomainPtr domain,
* not support this feature and will return an error if bandwidth
* is not 0.
*
* Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy
* migration. Use virDomainMigrateStartPostCopy to switch migration into
* the post-copy mode. See virDomainMigrateStartPostCopy for more details
* about post-copy.
*
* To see which features are supported by the current hypervisor,
* see virConnectGetCapabilities, /capabilities/host/migration_features.
*
@ -3748,6 +3754,7 @@ virDomainMigrate(virDomainPtr domain,
* automatically when supported).
* VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe.
* VIR_MIGRATE_OFFLINE Migrate offline
* VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy
*
* VIR_MIGRATE_TUNNELLED requires that VIR_MIGRATE_PEER2PEER be set.
* Applications using the VIR_MIGRATE_PEER2PEER flag will probably
@ -3784,6 +3791,11 @@ virDomainMigrate(virDomainPtr domain,
* not support this feature and will return an error if bandwidth
* is not 0.
*
* Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy
* migration. Use virDomainMigrateStartPostCopy to switch migration into
* the post-copy mode. See virDomainMigrateStartPostCopy for more details
* about post-copy.
*
* To see which features are supported by the current hypervisor,
* see virConnectGetCapabilities, /capabilities/host/migration_features.
*
@ -3968,6 +3980,11 @@ virDomainMigrate2(virDomainPtr domain,
* can use either VIR_MIGRATE_NON_SHARED_DISK or
* VIR_MIGRATE_NON_SHARED_INC as they are mutually exclusive.
*
* Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy
* migration. Use virDomainMigrateStartPostCopy to switch migration into
* the post-copy mode. See virDomainMigrateStartPostCopy for more details
* about post-copy.
*
* There are many limitations on migration imposed by the underlying
* technology - for example it may not be possible to migrate between
* different processors even with the same architecture, or between
@ -4208,6 +4225,7 @@ int virDomainMigrateUnmanagedCheckCompat(virDomainPtr domain,
* automatically when supported).
* VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe.
* VIR_MIGRATE_OFFLINE Migrate offline
* VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy
*
* The operation of this API hinges on the VIR_MIGRATE_PEER2PEER flag.
* If the VIR_MIGRATE_PEER2PEER flag is NOT set, the duri parameter
@ -4240,6 +4258,11 @@ int virDomainMigrateUnmanagedCheckCompat(virDomainPtr domain,
* not support this feature and will return an error if bandwidth
* is not 0.
*
* Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy
* migration. Use virDomainMigrateStartPostCopy to switch migration into
* the post-copy mode. See virDomainMigrateStartPostCopy for more details
* about post-copy.
*
* To see which features are supported by the current hypervisor,
* see virConnectGetCapabilities, /capabilities/host/migration_features.
*
@ -4321,6 +4344,7 @@ virDomainMigrateToURI(virDomainPtr domain,
* automatically when supported).
* VIR_MIGRATE_UNSAFE Force migration even if it is considered unsafe.
* VIR_MIGRATE_OFFLINE Migrate offline
* VIR_MIGRATE_POSTCOPY Enable (but do not start) post-copy
*
* The operation of this API hinges on the VIR_MIGRATE_PEER2PEER flag.
*
@ -4366,6 +4390,11 @@ virDomainMigrateToURI(virDomainPtr domain,
* not support this feature and will return an error if bandwidth
* is not 0.
*
* Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy
* migration. Use virDomainMigrateStartPostCopy to switch migration into
* the post-copy mode. See virDomainMigrateStartPostCopy for more details
* about post-copy.
*
* To see which features are supported by the current hypervisor,
* see virConnectGetCapabilities, /capabilities/host/migration_features.
*
@ -4446,6 +4475,11 @@ virDomainMigrateToURI2(virDomainPtr domain,
* can use either VIR_MIGRATE_NON_SHARED_DISK or
* VIR_MIGRATE_NON_SHARED_INC as they are mutually exclusive.
*
* Enabling the VIR_MIGRATE_POSTCOPY flag tells libvirt to enable post-copy
* migration. Use virDomainMigrateStartPostCopy to switch migration into
* the post-copy mode. See virDomainMigrateStartPostCopy for more details
* about post-copy.
*
* There are many limitations on migration imposed by the underlying
* technology - for example it may not be possible to migrate between
* different processors even with the same architecture, or between
@ -8868,14 +8902,15 @@ virDomainGetJobInfo(virDomainPtr domain, virDomainJobInfoPtr info)
*
* When @flags contains VIR_DOMAIN_JOB_STATS_COMPLETED, the function will
* return statistics about a recently completed job. Specifically, this
* flag may be used to query statistics of a completed incoming migration.
* Statistics of a completed job are automatically destroyed once read or
* when libvirtd is restarted. Note that time information returned for
* completed migrations may be completely irrelevant unless both source and
* destination hosts have synchronized time (i.e., NTP daemon is running on
* both of them). The statistics of a completed job can also be obtained by
* listening to a VIR_DOMAIN_EVENT_ID_JOB_COMPLETED event (on the source host
* in case of a migration job).
* flag may be used to query statistics of a completed incoming pre-copy
* migration (statistics for post-copy migration are only available on the
* source hsot). Statistics of a completed job are automatically destroyed
* once read or when libvirtd is restarted. Note that time information
* returned for completed migrations may be completely irrelevant unless both
* source and destination hosts have synchronized time (i.e., NTP daemon is
* running on both of them). The statistics of a completed job can also be
* obtained by listening to a VIR_DOMAIN_EVENT_ID_JOB_COMPLETED event (on the
* source host in case of a migration job).
*
* Returns 0 in case of success and -1 in case of failure.
*/
@ -9164,6 +9199,96 @@ virDomainMigrateGetMaxSpeed(virDomainPtr domain,
}
/**
* virDomainMigrateStartPostCopy:
* @domain: a domain object
* @flags: extra flags; not used yet, so callers should always pass 0
*
* Starts post-copy migration. This function has to be called while
* migration (initiated with VIR_MIGRATE_POSTCOPY flag) is in progress.
*
* Traditional pre-copy migration iteratively walks through guest memory
* pages and migrates those that changed since the previous iteration. The
* iterative phase stops when the number of dirty pages is low enough so that
* the virtual CPUs can be paused, all dirty pages transferred to the
* destination, where the virtual CPUs are unpaused, and all this can happen
* within a predefined downtime period. It's clear that this process may never
* converge if downtime is too short and/or the guest keeps changing a lot of
* memory pages.
*
* When migration is switched to post-copy mode, the virtual CPUs are paused
* immediately, only a minimum set of pages is transferred, and the CPUs are
* unpaused on destination. The source keeps sending all remaining memory pages
* to the destination while the guest is already running there. Whenever the
* guest tries to read a memory page which has not been migrated yet, the
* hypervisor has to tell the source to transfer that page in a priority
* channel. To minimize such page faults, it is a good idea to run at least one
* iteration of pre-copy migration before switching to post-copy.
*
* Post-copy migration is guaranteed to converge since each page is transferred
* at most once no matter how fast it changes. On the other hand once the
* guest is running on the destination host, the migration can no longer be
* rolled back because none of the hosts has complete state. If this happens,
* libvirt will leave the domain paused on both hosts with
* VIR_DOMAIN_PAUSED_POSTCOPY_FAILED reason. It's up to the upper layer to
* decide what to do in such case.
*
* The following domain life cycle events are emitted during post-copy
* migration:
* VIR_DOMAIN_EVENT_SUSPENDED_POSTCOPY (on the source) -- migration entered
* post-copy mode.
* VIR_DOMAIN_EVENT_RESUMED_POSTCOPY (on the destination) -- the guest is
* running on the destination host while some of its memory pages still
* remain on the source host; neither the source nor the destination host
* contain a complete guest state from this point until migration
* finishes.
* VIR_DOMAIN_EVENT_RESUMED_MIGRATED (on the destination),
* VIR_DOMAIN_EVENT_STOPPED_MIGRATED (on the source) -- migration finished
* successfully and the destination host holds a complete guest state.
* VIR_DOMAIN_EVENT_SUSPENDED_POSTCOPY_FAILED (on the destination) -- emitted
* when migration fails in post-copy mode and it's unclear whether any
* of the hosts has a complete guest state.
*
* The progress of a post-copy migration can be monitored normally using
* virDomainGetJobStats on the source host. Fetching statistics of a completed
* post-copy migration can also be done on the source host (by calling
* virDomainGetJobStats or listening to VIR_DOMAIN_EVENT_ID_JOB_COMPLETED
* event, but (in contrast to pre-copy migration) the statistics are not
* available on the destination host. Thus, VIR_DOMAIN_EVENT_ID_JOB_COMPLETED
* event is the only way of getting statistics of a completed post-copy
* migration of a transient domain (because the domain is removed after
* migration and there's no domain to run virDomainGetJobStats on).
*
* Returns 0 in case of success, -1 otherwise.
*/
int
virDomainMigrateStartPostCopy(virDomainPtr domain,
unsigned int flags)
{
virConnectPtr conn;
VIR_DOMAIN_DEBUG(domain);
virResetLastError();
virCheckDomainReturn(domain, -1);
conn = domain->conn;
virCheckReadOnlyGoto(conn->flags, error);
if (conn->driver->domainMigrateStartPostCopy) {
if (conn->driver->domainMigrateStartPostCopy(domain, flags) < 0)
goto error;
return 0;
}
virReportUnsupportedError();
error:
virDispatchError(conn);
return -1;
}
/**
* virConnectDomainEventRegisterAny:
* @conn: pointer to the connection

5
src/libvirt_public.syms
View File

@ -725,4 +725,9 @@ LIBVIRT_1.2.19 {
virDomainRename;
} LIBVIRT_1.2.17;
LIBVIRT_1.3.3 {
global:
virDomainMigrateStartPostCopy;
} LIBVIRT_1.2.19;
# .... define new API here using predicted next version number ....

1
src/remote/remote_driver.c
View File

@ -7763,6 +7763,7 @@ static virHypervisorDriver hypervisor_driver = {
.domainRename = remoteDomainRename, /* 1.2.19 */
.connectRegisterCloseCallback = remoteConnectRegisterCloseCallback, /* 1.3.2 */
.connectUnregisterCloseCallback = remoteConnectUnregisterCloseCallback, /* 1.3.2 */
.domainMigrateStartPostCopy = remoteDomainMigrateStartPostCopy, /* 1.3.3 */
};
static virNetworkDriver network_driver = {

13
src/remote/remote_protocol.x
View File

@ -3238,6 +3238,11 @@ struct remote_domain_event_callback_job_completed_msg {
remote_typed_param params<REMOTE_DOMAIN_JOB_STATS_MAX>;
};
struct remote_domain_migrate_start_post_copy_args {
remote_nonnull_domain dom;
unsigned int flags;
};
/*----- Protocol. -----*/
/* Define the program number, protocol version and procedure numbers here. */
@ -5740,5 +5745,11 @@ enum remote_procedure {
* @generate: both
* @acl: none
*/
REMOTE_PROC_DOMAIN_EVENT_CALLBACK_JOB_COMPLETED = 363
REMOTE_PROC_DOMAIN_EVENT_CALLBACK_JOB_COMPLETED = 363,
/**
* @generate: both
* @acl: domain:migrate
*/
REMOTE_PROC_DOMAIN_MIGRATE_START_POST_COPY = 364
};

5
src/remote_protocol-structs
View File

@ -2708,6 +2708,10 @@ struct remote_domain_event_callback_job_completed_msg {
remote_typed_param * params_val;
} params;
};
struct remote_domain_migrate_start_post_copy_args {
remote_nonnull_domain dom;
u_int flags;
};
enum remote_procedure {
REMOTE_PROC_CONNECT_OPEN = 1,
REMOTE_PROC_CONNECT_CLOSE = 2,
@ -3072,4 +3076,5 @@ enum remote_procedure {
REMOTE_PROC_CONNECT_CLOSE_CALLBACK_UNREGISTER = 361,
REMOTE_PROC_CONNECT_EVENT_CONNECTION_CLOSED = 362,
REMOTE_PROC_DOMAIN_EVENT_CALLBACK_JOB_COMPLETED = 363,
REMOTE_PROC_DOMAIN_MIGRATE_START_POST_COPY = 364,
};