Based-on: <20221004182430.97638-1-pet...@redhat.com> [PATCH v2 0/5] migration: Bug fixes (prepare for preempt-full)
Tree is here: https://github.com/xzpeter/qemu/tree/preempt-full RFC: https://lore.kernel.org/r/20220829165659.96046-1-pet...@redhat.com v1: https://lore.kernel.org/r/20220920225106.48451-1-pet...@redhat.com This patchset is v2 version of preempt-full series. v2 changelog: - Add r-bs - Rename release_lock to preempt_active [Dave] - Create MigrationAtomicStats structure, maintaining the 4 stats fields that may need atomic access since they'll be accessed by multiple threads. define them with Stat64. Add rich comment. [Dave] - One more patch added (patch 1) to fix another deadlock; not easy to reproduce but actually quite obvious.. The existing preempt code has reduced ramdom page req latency over 10Gbps network from ~12ms to ~500us which has already landed. This preempt-full series can further reduces that ~500us to ~230us per my initial test. Note that no new capability is needed, IOW it's fully compatible with the existing preempt mode. So the naming is actually not important but just to identify the difference on the binaries. The logic of the series is simple: send urgent pages in rp-return thread rather than migration thread. It also means rp-thread will take over the ownership of the newly created preempt channel. It can slow down rp-return thread on receiving page requests, but I don't really see a major issue with it so far but only benefits. For detailed performance numbers, please refer to the rfc cover letter. Please have a look, thanks. Peter Xu (15): migration: Take bitmap mutex when completing ram migration migration: Add postcopy_preempt_active() migration: Cleanup xbzrle zero page cache update logic migration: Trivial cleanup save_page_header() on same block check migration: Remove RAMState.f references in compression code migration: Yield bitmap_mutex properly when sending/sleeping migration: Use atomic ops properly for page accountings migration: Teach PSS about host page migration: Introduce pss_channel migration: Add pss_init() migration: Make PageSearchStatus part of RAMState migration: Move last_sent_block into PageSearchStatus migration: Send requested page directly in rp-return thread migration: Remove old preempt code around state maintainance migration: Drop rs->f migration/migration.c | 47 +-- migration/migration.h | 7 - migration/multifd.c | 4 +- migration/ram.c | 720 +++++++++++++++++++----------------------- migration/ram.h | 20 ++ 5 files changed, 379 insertions(+), 419 deletions(-) -- 2.37.3
