[Devel] [PATCH RHEL9 COMMIT] dm-ploop: use lockless lists for data ready pios
Konstantin Khorenko
khorenko at virtuozzo.com
Mon Jan 27 16:12:49 MSK 2025
The commit is pushed to "branch-rh9-5.14.0-427.44.1.vz9.80.x-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.44.1.vz9.80.6
------>
commit a71dbecdb6692d7465a3ca81160c233a12ab9ae1
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date: Fri Jan 24 17:36:18 2025 +0200
dm-ploop: use lockless lists for data ready pios
reduce locking for data ready pios chained to bat updates
https://virtuozzo.atlassian.net/browse/VSTOR-91821
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
======
Patchset description:
ploop: optimistations and scalling
Ploop processes requsts in a different threads in parallel
where possible which results in significant improvement in
performance and makes further optimistations possible.
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 (50):
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: 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 from wq to kthread
dm-ploop: move preparations of pios into the caller from worker
dm-ploop: fast path execution for reads
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: split cow processing into two functions
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: process pios via runners
dm-ploop: disable metadata writeback delay
dm-ploop: disable fast path
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 bat completion logic
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
Feature: dm-ploop: ploop target driver
---
drivers/md/dm-ploop-map.c | 15 ++++++++-------
drivers/md/dm-ploop.h | 2 +-
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 809ae3ee71ec..4b4facc79aba 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -62,7 +62,7 @@ void ploop_index_wb_init(struct ploop_index_wb *piwb, struct ploop *ploop)
piwb->md = NULL;
piwb->bat_page = NULL;
piwb->bi_status = 0;
- INIT_LIST_HEAD(&piwb->ready_data_pios);
+ init_llist_head(&piwb->llready_data_pios);
init_llist_head(&piwb->cow_llist);
/* For ploop_bat_write_complete() */
@@ -904,6 +904,7 @@ static void ploop_bat_write_complete(struct pio *pio, void *piwb_ptr,
LIST_HEAD(lready_pios);
struct llist_node *pos, *t;
struct llist_node *ll_cow_pios;
+ struct llist_node *ll_ready_pios;
int completed = atomic_read(&piwb->count) == 1;
if (completed) {
@@ -925,7 +926,7 @@ static void ploop_bat_write_complete(struct pio *pio, void *piwb_ptr,
if (completed)
piwb->completed = completed;
piwb->bi_status = bi_status;
- list_splice_init(&piwb->ready_data_pios, &lready_pios);
+ ll_ready_pios = llist_reverse_order(llist_del_all(&piwb->llready_data_pios));
spin_unlock_irqrestore(&piwb->lock, flags);
ll_cow_pios = llist_reverse_order(llist_del_all(&piwb->cow_llist));
@@ -934,7 +935,9 @@ static void ploop_bat_write_complete(struct pio *pio, void *piwb_ptr,
* End pending data bios.
*/
- while ((data_pio = ploop_pio_list_pop(&lready_pios)) != NULL) {
+ llist_for_each_safe(pos, t, ll_ready_pios) {
+ pio = list_entry((struct list_head *)pos, typeof(*aux_pio), list);
+ INIT_LIST_HEAD(&pio->list);
if (bi_status)
data_pio->bi_status = bi_status;
ploop_pio_endio(data_pio);
@@ -1222,7 +1225,7 @@ static bool ploop_data_pio_end(struct pio *pio)
spin_lock_irqsave(&piwb->lock, flags);
completed = piwb->completed;
if (!completed)
- list_add_tail(&pio->list, &piwb->ready_data_pios);
+ llist_add((struct llist_node *)(&pio->list), &piwb->llready_data_pios);
else if (!pio->bi_status)
pio->bi_status = piwb->bi_status;
spin_unlock_irqrestore(&piwb->lock, flags);
@@ -1842,9 +1845,7 @@ static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio)
goto err;
} else {
WRITE_ONCE(to[clu], 0);
- spin_lock_irqsave(&piwb->lock, flags);
- list_add_tail(&pio->list, &piwb->ready_data_pios);
- spin_unlock_irqrestore(&piwb->lock, flags);
+ llist_add((struct llist_node *)(&pio->list), &piwb->llready_data_pios);
}
kunmap_local(to);
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index 3f80d1750ffb..ad1033c0898a 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -101,7 +101,7 @@ struct ploop_index_wb {
struct md_page *md;
struct pio *pio;
struct page *bat_page;
- struct list_head ready_data_pios;
+ struct llist_head llready_data_pios;
struct llist_head cow_llist;
atomic_t count;
bool completed;
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