Looks good except one missed hunk.
We can handle excess pio->llist.next = NULL and INIT_LIST_HEADs, and
list_for_each_ENTRY_safe separately later, as those are not directly
connected to this rework.
note: Looks like you've accidentally over-wrote original patch authors.
Reviewed-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
On 2/12/25 17:32, Konstantin Khorenko wrote:
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(-)
--
Best regards, Tikhomirov Pavel
Senior Software Developer, Virtuozzo.
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