[Devel] [PATCH RHEL9 COMMIT] dm-ploop: BAT use only one list for writeback
Konstantin Khorenko
khorenko at virtuozzo.com
Mon Jan 27 16:12:42 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 efd67c1da6fbe692fabfea6b54b7c149fb21be3a
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date: Fri Jan 24 17:36:01 2025 +0200
dm-ploop: BAT use only one list for writeback
remove the wb_batch_list_prio, use only wb_batch_list and
use the md high_prio flag for immediate submission.
https://virtuozzo.atlassian.net/browse/VSTOR-91817
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 | 70 ++++++++++++++++++--------------------------
drivers/md/dm-ploop-target.c | 1 -
drivers/md/dm-ploop.h | 1 -
3 files changed, 29 insertions(+), 43 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 553603b95bf8..2419d60e3ec6 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -579,10 +579,6 @@ static void ploop_md_up_prio(struct ploop *ploop, struct md_page *md)
md->high_prio = true;
WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
-
- list_del(&md->wb_link);
- list_add(&md->wb_link, &ploop->wb_batch_list_prio);
-
out:
write_unlock_irqrestore(&ploop->bat_rwlock, flags);
}
@@ -1831,43 +1827,41 @@ static void ploop_process_resubmit_pios(struct ploop *ploop,
}
}
-static void ploop_submit_metadata_writeback_from_list(struct ploop *ploop,
- struct list_head *list)
+static void ploop_submit_metadata_writeback(struct ploop *ploop)
{
- struct md_page *md;
+ ktime_t ktime, ktimeout;
+ LIST_HEAD(ll_skipped);
+ struct md_page *md, *mtmp;
+ int send_all;
- while (1) {
+ ktime = ktime_get();
+ ktimeout = ktime_add_ms(ktime, ploop->md_submit_delay_ms);
+ send_all = ktime_after(ktime, ktimeout);
+ /*
+ * Pages are set dirty so no one must touch lists
+ * if new md entries are dirtied they are added at the start of the list
+ */
+ list_for_each_entry_safe(md, mtmp, &ploop->wb_batch_list, wb_link) {
write_lock_irq(&ploop->bat_rwlock);
- md = list_first_entry_or_null(list, struct md_page, wb_link);
- if (!md) {
+ list_del_init(&md->wb_link);
+ if (md->high_prio || send_all) {
+ /* L1L2 mustn't be redirtyed, when wb in-flight! */
+ WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
+ WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
+ set_bit(MD_WRITEBACK, &md->status);
+ clear_bit(MD_DIRTY, &md->status);
+ md->high_prio = false;
+ write_unlock_irq(&ploop->bat_rwlock);
+ ploop_index_wb_submit(ploop, md->piwb);
+ } else {
+ list_add_tail(&md->wb_link, &ll_skipped);
write_unlock_irq(&ploop->bat_rwlock);
- break;
}
- list_del_init(&md->wb_link);
- /* L1L2 mustn't be redirtyed, when wb in-flight! */
-
- WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
- WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
- set_bit(MD_WRITEBACK, &md->status);
- clear_bit(MD_DIRTY, &md->status);
- md->high_prio = false;
- write_unlock_irq(&ploop->bat_rwlock);
-
- ploop_index_wb_submit(ploop, md->piwb);
}
-}
-
-static void ploop_submit_metadata_writeback(struct ploop *ploop)
-{
- ktime_t time;
-
- ploop_submit_metadata_writeback_from_list(ploop, &ploop->wb_batch_list_prio);
+ write_lock_irq(&ploop->bat_rwlock);
+ list_splice(&ll_skipped, &ploop->wb_batch_list);
+ write_unlock_irq(&ploop->bat_rwlock);
- time = ktime_get();
- if (ktime_after(time, ktime_add_ms(ploop->last_md_submit, ploop->md_submit_delay_ms))) {
- ploop->last_md_submit = time;
- ploop_submit_metadata_writeback_from_list(ploop, &ploop->wb_batch_list);
- }
}
static void process_ploop_fsync_work(struct ploop *ploop, struct llist_node *llflush_pios)
@@ -2016,16 +2010,10 @@ static void ploop_prepare_flush(struct ploop *ploop, struct pio *pio)
write_lock_irq(&ploop->bat_rwlock);
- list_for_each_entry(md, &ploop->wb_batch_list_prio, wb_link) {
- md_inflight++;
- md->piwb->flush_pio = flush_pio;
- }
-
list_for_each_entry_safe(md, n, &ploop->wb_batch_list, wb_link) {
md_inflight++;
md->piwb->flush_pio = flush_pio;
- list_del(&md->wb_link);
- list_add_tail(&md->wb_link, &ploop->wb_batch_list_prio);
+ md->high_prio = true;
}
atomic_set(&flush_pio->md_inflight, md_inflight);
diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index f714c2cb540f..87827b90aeef 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -423,7 +423,6 @@ static int ploop_ctr(struct dm_target *ti, unsigned int argc, char **argv)
INIT_LIST_HEAD(&ploop->cluster_lk_list);
init_llist_head(&ploop->wb_batch_llist);
INIT_LIST_HEAD(&ploop->wb_batch_list);
- INIT_LIST_HEAD(&ploop->wb_batch_list_prio);
ploop->last_md_submit = 0;
ploop->md_submit_delay_ms = PLOOP_DEFAULT_METADATA_SUBMIT_DELAY;
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index c08acb1a3cc9..02612339405c 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -178,7 +178,6 @@ struct ploop {
struct llist_head wb_batch_llist;
struct list_head wb_batch_list;
- struct list_head wb_batch_list_prio;
ktime_t last_md_submit;
#define PLOOP_DEFAULT_METADATA_SUBMIT_DELAY 10000
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