[libvirt] [PATCH v2 0/8] Post-copy live migration support

Qemu currently implements pre-copy live migration. VM memory pages are first copied from the source hypervisor to the destination, potentially multiple times as pages get dirtied during transfer, then VCPU state is migrated. Unfortunately, if the VM dirties memory faster than the network bandwidth, then pre-copy cannot finish. `virsh` currently includes an option to suspend a VM after a timeout, so that migration may finish, but at the expense of downtime. A future version of qemu will implement post-copy live migration. The VCPU state is first migrated to the destination hypervisor, then memory pages are pulled from the source hypervisor. Post-copy has the potential to do migration with zero-downtime, despite the VM dirtying pages fast, with minimum performance impact. On the other hand, one post-copy is in progress, any network failure would render the VM unusable, as its memory is partitioned between the source and destination hypervisor. Therefore, post-copy should only be used when necessary. Post-copy migration in qemu will work as follows: (1) The `x-postcopy-ram` migration capability needs to be set. (2) Migration is started. (3) When the user decides so, post-copy migration is activated by sending the `migrate-start-postcopy` command. Qemu acknowledges by setting migration status to `postcopy-active`. v2: - Fixed formatting - Set target version to libvirt 1.2.10 - Only use JSON monitor - Renamed `qemuMigrateStartPostCopy` to `qemuDomainMigrateStartPostCopy` - Added parameter `flags` to domainMigrateStartPostCopy (currently unused) - Misc fixes required for `make check` - Stop perform phase, when post-copy starts - Wait for post-copy completion in confirm phase, before killing source VM Implementation note: `qemuMigrationWaitForCompletion` is overloaded. When called the first time it waits for post-copy to start, when called the second time it waits for post-copy to complete. I did so to reduce code duplication, but am not sure this is the best solution. Cristian Klein (8): Added public API to enable post-copy migration Added public API to start post-copy migration Added low-level API to qemu post-copy migration Implemented VIR_MIGRATE_POSTCOPY in qemu driver Added job type VIR_DOMAIN_JOB_PHASE1_COMPLETED Implemented post-copy migration logic in qemu Implement virDomainMigrateStartPostCopy in qemu virsh: add postcopy-after option to migrate command include/libvirt/libvirt.h.in | 5 +++ src/driver.h | 5 +++ src/libvirt.c | 46 ++++++++++++++++++++++++ src/libvirt_public.syms | 5 +++ src/qemu/qemu_driver.c | 58 ++++++++++++++++++++++++++++++ src/qemu/qemu_migration.c | 85 ++++++++++++++++++++++++++++++++++++++++++-- src/qemu/qemu_migration.h | 3 +- src/qemu/qemu_monitor.c | 24 +++++++++++-- src/qemu/qemu_monitor.h | 4 +++ src/qemu/qemu_monitor_json.c | 23 +++++++++++- src/qemu/qemu_monitor_json.h | 1 + src/remote/remote_driver.c | 1 + src/remote/remote_protocol.x | 13 ++++++- src/remote_protocol-structs | 5 +++ tools/virsh-domain.c | 75 ++++++++++++++++++++++++++++++++++++-- tools/virsh.pod | 5 +++ 16 files changed, 347 insertions(+), 11 deletions(-) -- 1.9.1