Ploop processes requsts in a different threads in parallel where possible which results in significant improvement in performance and makes further optimistations possible.
v1: - addressed feedback, i've left a few requests to merge changes into bigger patches out, as to keep changes in smaller chunks - patches merged and separated changes - generic cleanup - fix endio for md page writeback - background async allocation of space - move enospc pios dispatch from timer to thread - fixed allocations in atomic context - fixed locking wrt userspace/interrupt context - reworked discard cleanup - removed workqueue, only use kthread code - make metadata writeback works in parallel - end fsync pios in parallel - fixed current flags manipulation v2: - commit "dm-ploop: introduce pio.llist" appeared It introduces the the pio.llist along with pio.list, gathered in an union, so during the processes of switching between list users and llist users, we could use appropriate fields without strict pointers casts. TODO: - there are multiple INIT_LIST_HEAD() left in the code, most of them are just not needed, but let's looks precisely at each case. Same for "pio->llist.next = NULL;" - md_page.wb_link switched to llist and later - back to list along with introducing ploop.wb_batch_list and ploop.wb_batch_list_prio. Need to understand if we want the latter to be lists or llists and don't push wb_link back and forth. RFC series: v6 changes: - locking fixes - use READ_ONCE/WRITE_ONCE - properly handle DIO errors (ENOTBLK) - added support for data pios with REQ_FUA - convert more lists to lockless variants - resize/grow is good v5 with changes in v4: - BAT writeback delay - Lists/Locking moving to lockless lists to reduce locking - Requests are prepared in the caller to reduce load of worker thread - REQ_FUA and REQ_PREFLUSH support - Convert bit fields to use atomic bitops - reduce locking - remove fsync worker to guarantee order of execution - Map all md pages at creation time - they are only freed on device destroy Known bugs: - delayed metadata writeback is not working and is missing error handling - patch to disable it until fixed - fast path is not working - causes rcu lockups - patch to disable it Further improvements: - optimize md pages lookups Alexander Atanasov (42): dm-ploop: md_pages map all pages at creation time dm-ploop: Use READ_ONCE/WRITE_ONCE to access md page data dm-ploop: fsync after all pios are sent dm-ploop: move md status to use proper bitops dm-ploop: convert wait_list and wb_batch_llist to use lockless lists dm-ploop: convert enospc handling to use lockless lists dm-ploop: convert suspended_pios list to use lockless list dm-ploop: move from wq to kthread dm-ploop: do not use a wrapper for set_bit to make a page writeback dm-ploop: BAT use only one list for writeback dm-ploop: make md writeback timeout to be per page dm-ploop: add interface to disable bat writeback delay dm-ploop: convert wb_batch_list to lockless variant dm-ploop: convert high_prio to status dm-ploop: convert md page rw lock to spin lock dm-ploop: convert bat_rwlock to bat_lock spinlock dm-ploop: prepare bat updates under bat_lock dm-ploop: make ploop_bat_write_complete ready for parallel pio completion dm-ploop: make ploop_submit_metadata_writeback return number of requests sent dm-ploop: introduce pio runner threads dm-ploop: add pio list ids to be used when passing pios to runners dm-ploop: disable metadata writeback delay dm-ploop: use lockless lists for chained cow updates list dm-ploop: use lockless lists for data ready pios dm-ploop: give runner threads better name dm-ploop: resize operation - add holes bitmap locking dm-ploop: remove unnecessary operations dm-ploop: use filp per thread dm-ploop: catch if we try to advance pio past bio end dm-ploop: support REQ_FUA for data pios dm-ploop: proplerly access nr_bat_entries dm-ploop: fix locking and improve error handling when submitting pios dm-ploop: fix how ENOTBLK is handled dm-ploop: sync when suspended or stopping dm-ploop: rework logic in pio processing dm-ploop: end fsync pios in parallel dm-ploop: make filespace preallocations async dm-ploop: resubmit enospc pios from dispatcher thread dm-ploop: dm-ploop: simplify discard completion dm-ploop: use GFP_ATOMIC instead of GFP_NOIO dm-ploop: fix locks used in mixed context dm-ploop: fix how current flags are managed inside threads Andrey Zhadchenko (13): dm-ploop: do not flush after metadata writes dm-ploop: set IOCB_DSYNC on all FUA requests dm-ploop: remove extra ploop_cluster_is_in_top_delta() dm-ploop: introduce per-md page locking dm-ploop: reduce BAT accesses on discard completion dm-ploop: simplify llseek dm-ploop: speed up ploop_prepare_bat_update() dm-ploop: make new allocations immediately visible in BAT dm-ploop: drop ploop_cluster_is_in_top_delta() dm-ploop: do not wait for BAT update for non-FUA requests dm-ploop: add delay for metadata writeback dm-ploop: submit all postponed metadata on REQ_OP_FLUSH dm-ploop: handle REQ_PREFLUSH Konstantin Khorenko (10): dm-ploop: drop md_page.wb_link initialization dm-ploop: introduce pio.llist dm-ploop: convert the rest of the lists to use llist variant dm-ploop: combine processing of pios thru prepare list and remove fsync worker dm-ploop: move preparations of pios into the caller from worker dm-ploop: fast path execution for reads dm-ploop: split cow processing into two functions dm-ploop: process pios via runners dm-ploop: disable fast path dm-ploop: rework bat completion logic drivers/md/dm-ploop-bat.c | 74 +- drivers/md/dm-ploop-cmd.c | 174 ++-- drivers/md/dm-ploop-map.c | 1599 ++++++++++++++++++++++++---------- drivers/md/dm-ploop-target.c | 168 +++- drivers/md/dm-ploop.h | 120 ++- 5 files changed, 1484 insertions(+), 651 deletions(-) -- 2.43.5 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel