Hi, everyone. The details for instant snapshot are given in main patch "qemu: support instant snapshots". Here I only want to mention two moments. First as instant snapshot API is synchronous we need to add an event that snapshot moment in time is passed so that client is free to make changes to guest. This way client can make use of instant snapshot while memory is still being written to disk. Second there is work in progress on adding asynchronous revert to snapshot [1]. The idea is to write memory during snapshot in such a way that it is possible to do a revert to snapshot in background. Namely start guest on revert with only minimal amount of memory restored from disk and then restore memory in background in postcopy migration fashion. In order to make it possible snapshot memory should be written to disk not just as plain migration stream. Thus the [1] patch adds a special tool to write the migration stream during snapshot. So if/when patch [1] will be merged I plan to add 'instant revert' mode to snapshot too. [1] [RFC PATCH v2 0/7] migration/snapshot: External snapshot utility https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg03619.html Nikolay Shirokovskiy (9): qemu: make snap possibility check before pausing CPUS qemu: snapshot: remove redundant flag setting qemu: don't bother saving ret code from qemuDomainSaveMemory qemu: move virQEMUSaveDataFree auto decl to header qemu: factor out qemuDomainSnapshotSaveMemory qemu: introduce qemuMigrationParamsSetCapability qemu: support instant mode in qemuMigrationSrcToFile qemu: support instant snapshots virsh: add --instant flag to snapshot-create docs/manpages/virsh.rst | 8 +- include/libvirt/libvirt-domain-snapshot.h | 2 + src/qemu/qemu_driver.c | 4 +- src/qemu/qemu_migration.c | 20 ++- src/qemu/qemu_migration.h | 1 + src/qemu/qemu_migration_params.c | 13 ++ src/qemu/qemu_migration_params.h | 5 + src/qemu/qemu_saveimage.c | 4 +- src/qemu/qemu_saveimage.h | 2 + src/qemu/qemu_snapshot.c | 158 +++++++++++++++------- tools/virsh-snapshot.c | 6 + 11 files changed, 162 insertions(+), 61 deletions(-) -- 2.27.0
