Currently, a huge VM with high memory overload may take a long time to increase its maximum throttle percentage. The root cause is that the current auto-converge throttle logic doesn't look like it will scale because migration_trigger_throttle() is only called for each iteration, so it won't be invoked for a long time if one iteration can take a long time.
This patchset provides two refinements aiming at the above case. 1: The periodic CPU throttle. As Peter points out, "throttle only for each sync, sync for each iteration" may make sense in the old days, but perhaps not anymore. So we introduce perioidic CPU throttle implementation for migration, which is a trade-off between synchronization overhead and CPU throttle impact. 2: The responsive CPU throttle. We present new criteria called "dirty ratio" to help improve the detection accuracy and hence accelerate the throttle's invocation. The RFC version of the refinement may be a rudimentary implementation, I would appreciate hearing more feedback. Yong, thanks. Hyman Huang (10): migration: Introduce structs for periodic CPU throttle migration: Refine util functions to support periodic CPU throttle qapi/migration: Introduce periodic CPU throttling parameters qapi/migration: Introduce the iteration-count migration: Introduce util functions for periodic CPU throttle migration: Support periodic CPU throttle tests/migration-tests: Add test case for periodic throttle migration: Introduce cpu-responsive-throttle parameter migration: Support responsive CPU throttle tests/migration-tests: Add test case for responsive CPU throttle include/exec/ram_addr.h | 117 ++++++++++++++++-- include/exec/ramblock.h | 45 +++++++ migration/migration-hmp-cmds.c | 25 ++++ migration/migration-stats.h | 4 + migration/migration.c | 12 ++ migration/options.c | 74 +++++++++++ migration/options.h | 3 + migration/ram.c | 218 ++++++++++++++++++++++++++++++--- migration/ram.h | 4 + migration/trace-events | 4 + qapi/migration.json | 45 ++++++- tests/qtest/migration-test.c | 77 +++++++++++- 12 files changed, 600 insertions(+), 28 deletions(-) -- 2.39.1
