This series is the third attempt[0] at substantially improving live-restore performance. This time, a fully async- and concurrency safe LRU cache is implemented, and a new CachedChunkReader is used to provide lock-free reading from a remote chunk source. The big performance improvements come from removing the global Mutex synchronising all read_image_at requests in the QEMU library and the shared LRU cache.
The idea of using 'mmap' to alleviate memory pressure was dropped in favor of using a shared cache between drives. This provides about the same performance improvement in typical live-restore scenarios, but with a fixed memory requirement, independant of drives. Adding 'mmap' caching is doable, but the Rust code really doesn't look very nice with it, and I think it's not necessary in this version... Anyway, I figured out how to better benchmark the changes too, and can now reproduce the performance gains very reliably. Below is a (gnu)plot of running 40 live-restores of a Windows 10 VM with a single 32GB disk, first with the currently shipping libproxmox-backup-qemu0 (A) and then with the patched one from this series (B). Testing was done with QEMU 6.0. seconds 240 +-----------------------------------------------------------------------+ | + + + + + + A + | 230 |-+ A A A +-| | A A A AA A A A A | 220 |-+ A AA A A +-| | A A A A A A AA A A | 210 |-+ A A A A A A A-| | A | 200 |-+ A +-| | | 190 |-+ +-| | | 180 |-A +-| | | 170 |-+ +-| | B B B | 160 |-B B B B B B B +-| | B B B B B | 150 |-+ BB B BB B B B B B B B B-| | B + B + + B + B B + B + B B + B | 140 +-----------------------------------------------------------------------+ 0 5 10 15 20 25 30 35 40 iteration 1.0.3-1 A patched B [0] see: https://lists.proxmox.com/pipermail/pbs-devel/2021-April/002932.html proxmox-backup: Stefan Reiter (7): tools/BroadcastFuture: add testcase for better understanding tools: add AsyncLruCache as a wrapper around sync LruCache backup: add CachedChunkReader utilizing AsyncLruCache backup: add AsyncRead/Seek to CachedChunkReader replace AsyncIndexReader with SeekableCachedChunkReader backup: remove AsyncIndexReader tools/lru_cache: make minimum capacity 1 src/api2/admin/datastore.rs | 4 +- src/backup.rs | 4 +- src/backup/async_index_reader.rs | 215 ------------------------- src/backup/cached_chunk_reader.rs | 199 +++++++++++++++++++++++ src/bin/proxmox_backup_client/mount.rs | 4 +- src/tools.rs | 1 + src/tools/async_lru_cache.rs | 135 ++++++++++++++++ src/tools/broadcast_future.rs | 11 ++ src/tools/lru_cache.rs | 1 + 9 files changed, 353 insertions(+), 221 deletions(-) delete mode 100644 src/backup/async_index_reader.rs create mode 100644 src/backup/cached_chunk_reader.rs create mode 100644 src/tools/async_lru_cache.rs proxmox-backup-qemu: Stefan Reiter (2): add shared_cache module access: use CachedChunkReader src/lib.rs | 7 ++++++- src/restore.rs | 30 ++++++++---------------------- src/shared_cache.rs | 36 ++++++++++++++++++++++++++++++++++++ 3 files changed, 50 insertions(+), 23 deletions(-) create mode 100644 src/shared_cache.rs -- 2.30.2 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel