How to use:
1. Enable write-tracking migration capability
virsh qemu-monitor-command <domain> --hmp migrate_set_capability
background-snapshot on
2. Start the external migration to a file
virsh qemu-monitor-command <domain> --hmp migrate exec:'cat > ./vm_state'
3. Wait for the migration finish and check that the migration has completed.
state.
Changes v13->v14:
* 1. Removed unneeded '#ifdef CONFIG_LINUX' from [PATCH 1/5] where #ifdef'ed
* code was originally introduced. In v13 removed #ifdef's appeared to be
* a diff in [PATCH 4/5] on top of previous patches.
Changes v12->v13:
* 1. Fixed codestyle problem for checkpatch.
Changes v11->v12:
* 1. Consolidated UFFD-related code under single #if defined(__linux__).
* 2. Abandoned use of pre/post hooks in ram_find_and_save_block() in favour
* of more compact code fragment in ram_save_host_page().
* 3. Refactored/simplified eBPF code in userfaultfd-wrlat.py script.
Changes v10->v11:
* 1. Updated commit messages.
Changes v9->v10:
* 1. Fixed commit message for [PATCH v9 1/5].
Changes v8->v9:
* 1. Fixed wrong cover letter subject.
Changes v7->v8:
* 1. Fixed coding style problems to pass checkpatch.
Changes v6->v7:
* 1. Fixed background snapshot on suspended guest: call qemu_system_wakeup_request()
* before stopping VM to make runstate transition valid.
* 2. Disabled dirty page logging and log syn when 'background-snapshot' is enabled.
* 3. Introduced 'userfaultfd-wrlat.py' script to analyze UFFD write fault latencies.
Changes v5->v6:
* 1. Consider possible hot pluggin/unpluggin of memory device - don't use static
* for write-tracking support level in migrate_query_write_tracking(), check
* each time when one tries to enable 'background-snapshot' capability.
Changes v4->v5:
* 1. Refactored util/userfaultfd.c code to support features required by postcopy.
* 2. Introduced checks for host kernel and guest memory backend compatibility
* to 'background-snapshot' branch in migrate_caps_check().
* 3. Switched to using trace_xxx instead of info_report()/error_report() for
* cases when error message must be hidden (probing UFFD-IO) or info may be
* really littering output if goes to stderr.
* 4 Added RCU_READ_LOCK_GUARDs to the code dealing with RAM block list.
* 5. Added memory_region_ref() for each RAM block being wr-protected.
* 6. Reused qemu_ram_block_from_host() instead of custom RAM block lookup routine.
* 7. Refused from using specific hwaddr/ram_addr_t in favour of void */uint64_t.
* 8. Currently dropped 'linear-scan-rate-limiting' patch. The reason is that
* that choosen criteria for high-latency fault detection (i.e. timestamp of
* UFFD event fetch) is not representative enough for this task.
* At the moment it looks somehow like premature optimization effort.
* 8. Dropped some unnecessary/unused code.
Andrey Gruzdev (5):
migration: introduce 'background-snapshot' migration capability
migration: introduce UFFD-WP low-level interface helpers
migration: support UFFD write fault processing in ram_save_iterate()
migration: implementation of background snapshot thread
migration: introduce 'userfaultfd-wrlat.py' script
include/exec/memory.h | 8 +
include/qemu/userfaultfd.h | 35 ++++
migration/migration.c | 357 ++++++++++++++++++++++++++++++++++-
migration/migration.h | 4 +
migration/ram.c | 303 ++++++++++++++++++++++++++++-
migration/ram.h | 6 +
migration/savevm.c | 1 -
migration/savevm.h | 2 +
migration/trace-events | 2 +
qapi/migration.json | 7 +-
scripts/userfaultfd-wrlat.py | 122 ++++++++++++
util/meson.build | 1 +
util/trace-events | 9 +
util/userfaultfd.c | 345 +++++++++++++++++++++++++++++++++
14 files changed, 1190 insertions(+), 12 deletions(-)
create mode 100644 include/qemu/userfaultfd.h
create mode 100755 scripts/userfaultfd-wrlat.py
create mode 100644 util/userfaultfd.c
--
2.25.1