[Devel] [PATCH RHEL9 COMMIT] dm-ploop: process pios via runners
Konstantin Khorenko
khorenko at virtuozzo.com
Mon Jan 27 16:12:47 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 eb6c355512b3263b2d152cf95c2b5927b8cf96db
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date: Fri Jan 24 17:36:14 2025 +0200
dm-ploop: process pios via runners
Process pios in runner threads while preserving order.
Metadata writeback requries all prios pios to be processed,
since they can generate updates, so we have to wait before
processing writeback. Fsync is yet sequential too.
Both can be improved in a next iterration.
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 | 138 ++++++++++++++++++++--------------------------
1 file changed, 59 insertions(+), 79 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 9f19e0cb9bf7..037d7806b179 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1537,17 +1537,6 @@ static void ploop_process_one_delta_cow(struct ploop *ploop, struct pio *aux_pio
}
}
-static void ploop_process_delta_cow(struct ploop *ploop,
- struct llist_node *cow_llist)
-{
- struct llist_node *pos, *t;
- struct pio *aux_pio;
-
- llist_for_each_safe(pos, t, cow_llist) {
- aux_pio = list_entry((struct list_head *)pos, typeof(*aux_pio), list);
- ploop_process_one_delta_cow(ploop, aux_pio);
- }
-}
/*
* This allocates a new clu (if clu wb is not pending yet),
* or tries to attach a bio to a planned page index wb.
@@ -1705,7 +1694,8 @@ void ploop_index_wb_submit(struct ploop *ploop, struct ploop_index_wb *piwb)
pio->endio_cb = ploop_bat_write_complete;
pio->endio_cb_data = piwb;
- ploop_submit_rw_mapped(ploop, pio);
+ pio->queue_list_id = PLOOP_LIST_WRITEBACK;
+ ploop_runners_add_work(ploop, pio);
}
static struct bio_vec *ploop_create_bvec_from_rq(struct request *rq)
@@ -1796,20 +1786,6 @@ static void ploop_prepare_embedded_pios(struct ploop *ploop,
}
}
-static void ploop_process_deferred_pios(struct ploop *ploop,
- struct llist_head *pios)
-{
- struct pio *pio;
-
- struct llist_node *pos, *t;
-
- llist_for_each_safe(pos, t, pios->first) {
- pio = list_entry((struct list_head *)pos, typeof(*pio), list);
- INIT_LIST_HEAD(&pio->list); /* until type is changed */
- ploop_process_one_deferred_bio(ploop, pio);
- }
-}
-
static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio)
{
bool bat_update_prepared = false;
@@ -1869,39 +1845,12 @@ static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio)
ploop_pio_endio(pio);
}
-static void ploop_process_discard_pios(struct ploop *ploop,
- struct llist_node *discpios)
-{
- struct pio *pio;
- struct llist_node *pos, *t;
-
- llist_for_each_safe(pos, t, discpios) {
- pio = list_entry((struct list_head *)pos, typeof(*pio), list);
- INIT_LIST_HEAD(&pio->list);
- ploop_process_one_discard_pio(ploop, pio);
- }
-}
-
-static void ploop_process_resubmit_pios(struct ploop *ploop,
- struct llist_node *llpios)
-{
- struct pio *pio;
- struct llist_node *pos, *t;
-
- llist_for_each_safe(pos, t, llpios) {
- pio = list_entry((struct list_head *)pos, typeof(*pio), list);
- pio->queue_list_id = PLOOP_LIST_INVALID;
- INIT_LIST_HEAD(&pio->list); /* Until type is changed */
- ploop_submit_rw_mapped(ploop, pio);
- }
-}
-
static inline int ploop_runners_have_pending(struct ploop *ploop)
{
return atomic_read(&ploop->kt_worker->inflight_pios);
}
-static int ploop_submit_metadata_writeback(struct ploop *ploop)
+static inline int ploop_submit_metadata_writeback(struct ploop *ploop, int force)
{
unsigned long flags;
LIST_HEAD(ll_skipped);
@@ -1922,7 +1871,7 @@ static int ploop_submit_metadata_writeback(struct ploop *ploop)
*/
llist_for_each_safe(pos, t, ll_wb_batch) {
md = list_entry((struct list_head *)pos, typeof(*md), wb_link);
- if (!llist_empty(&md->wait_llist) ||
+ if (!llist_empty(&md->wait_llist) || force ||
test_bit(MD_HIGHPRIO, &md->status) ||
time_before(md->dirty_timeout, timeout) ||
ploop->force_md_writeback) {
@@ -1942,11 +1891,11 @@ static int ploop_submit_metadata_writeback(struct ploop *ploop)
return ret;
}
-static void process_ploop_fsync_work(struct ploop *ploop, struct llist_node *llflush_pios)
+static int process_ploop_fsync_work(struct ploop *ploop, struct llist_node *llflush_pios)
{
struct file *file;
struct pio *pio;
- int ret;
+ int ret, npios = 0;
struct llist_node *pos, *t;
file = ploop_top_delta(ploop)->file;
@@ -1963,6 +1912,7 @@ static void process_ploop_fsync_work(struct ploop *ploop, struct llist_node *llf
}
ploop_pio_endio(pio);
}
+ return npios;
}
static inline int ploop_runners_add_work(struct ploop *ploop, struct pio *pio)
@@ -2002,6 +1952,7 @@ void do_ploop_run_work(struct ploop *ploop)
struct llist_node *llresubmit;
struct llist_node *llflush_pios;
unsigned int old_flags = current->flags;
+ int npios;
current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
@@ -2013,33 +1964,55 @@ void do_ploop_run_work(struct ploop *ploop)
llcow_pios = llist_del_all(&ploop->pios[PLOOP_LIST_COW]);
/* add old deferred back to the list */
- if (lldeferred_pios) {
- struct llist_node *pos, *t;
- /* Add one by one we need last for batch add */
- llist_for_each_safe(pos, t, lldeferred_pios) {
- llist_add(pos, &deferred_pios);
- }
- }
+ if (lldeferred_pios)
+ ploop_runners_add_work_list(ploop, lldeferred_pios);
- ploop_prepare_embedded_pios(ploop, llembedded_pios, &deferred_pios);
+ if (llembedded_pios)
+ ploop_prepare_embedded_pios(ploop, llist_reverse_order(llembedded_pios),
+ &deferred_pios);
llflush_pios = llist_del_all(&ploop->pios[PLOOP_LIST_FLUSH]);
if (llresubmit)
- ploop_process_resubmit_pios(ploop, llist_reverse_order(llresubmit));
+ ploop_runners_add_work_list(ploop, llresubmit);
- ploop_process_deferred_pios(ploop, &deferred_pios);
+ ploop_runners_add_work_list(ploop, deferred_pios.first);
if (lldiscard_pios)
- ploop_process_discard_pios(ploop, llist_reverse_order(lldiscard_pios));
+ ploop_runners_add_work_list(ploop, lldiscard_pios);
if (llcow_pios)
- ploop_process_delta_cow(ploop, llist_reverse_order(llcow_pios));
+ ploop_runners_add_work_list(ploop, llcow_pios);
- ploop_submit_metadata_writeback(ploop);
+ /* wait for all pios to be executed before metadata updates */
+ current->flags = old_flags;
+ wait_event_interruptible(ploop->dispatcher_wq_data, (!ploop_runners_have_pending(ploop)));
+ current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+
+ /* if we have a flush we must sync md data too */
+ npios = ploop_submit_metadata_writeback(ploop, !!llflush_pios | ploop->force_md_writeback);
- if (llflush_pios)
- process_ploop_fsync_work(ploop, llist_reverse_order(llflush_pios));
+ if (llflush_pios) {
+ if (npios) {
+ /* wait for metadata writeback to complete */
+ current->flags = old_flags;
+ /* First wait all pios to be processed */
+ wait_event_interruptible(ploop->dispatcher_wq_data,
+ (!ploop_runners_have_pending(ploop)));
+ current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ }
+ /* Now process fsync pios after we have done all other */
+ npios = process_ploop_fsync_work(ploop, llflush_pios);
+ /* Since dispatcher is single thread no other work can be queued */
+#ifdef USE_RUNNERS__NOT_READY
+ if (npios) {
+ current->flags = old_flags;
+ wait_event_interruptible(ploop->dispatcher_wq_fsync,
+ atomic_read(&wrkr->fsync_pios) != 0);
+ current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ }
+#endif
+ }
current->flags = old_flags;
}
@@ -2141,8 +2114,9 @@ int ploop_worker(void *data)
llist_empty(&ploop->llresubmit_pios) &&
!ploop->force_md_writeback) {
if (kthread_should_stop()) {
- wait_event_interruptible(ploop->dispatcher_wq_data,
- (!ploop_runners_have_pending(ploop)));
+ wait_event_interruptible(
+ ploop->dispatcher_wq_data,
+ (!ploop_runners_have_pending(ploop)));
__set_current_state(TASK_RUNNING);
break;
}
@@ -2155,7 +2129,7 @@ int ploop_worker(void *data)
cond_resched(); /* give other processes chance to run */
if (kthread_should_stop()) {
wait_event_interruptible(ploop->dispatcher_wq_data,
- (!ploop_runners_have_pending(ploop)));
+ (!ploop_runners_have_pending(ploop)));
__set_current_state(TASK_RUNNING);
break;
}
@@ -2202,6 +2176,7 @@ static int ploop_prepare_flush(struct ploop *ploop, struct pio *pio)
spin_lock_irqsave(&ploop->bat_lock, flags);
llist_for_each_safe(pos, t, ploop->wb_batch_llist.first) {
md = list_entry((struct list_head *)pos, typeof(*md), wb_link);
+ WARN_ON(md->piwb->flush_pio);
md_inflight++;
md->piwb->flush_pio = flush_pio;
set_bit(MD_HIGHPRIO, &md->status);
@@ -2218,8 +2193,8 @@ static void ploop_submit_embedded_pio(struct ploop *ploop, struct pio *pio)
struct ploop_rq *prq = pio->endio_cb_data;
struct request *rq = prq->rq;
LLIST_HEAD(deferred_pios);
+ int ret = 0;
struct pio *spio;
- int ret;
if (blk_rq_bytes(rq)) {
pio->queue_list_id = PLOOP_LIST_PREPARE;
@@ -2239,15 +2214,20 @@ static void ploop_submit_embedded_pio(struct ploop *ploop, struct pio *pio)
ret = ploop_prepare_flush(ploop, pio);
if (ret < 0)
return;
+ /*
+ * Either we have a preflush pio with queue_list_id set to PLOOP_LIST_FLUSH
+ * or it is attached to md writeback
+ * only if it is zero, no inflight then fall thru
+ */
if (ret > 0)
goto out;
- /* Will add to prepare list and schedule work */
+ /* if it is zero we will process it here */
}
if (pio->queue_list_id == PLOOP_LIST_FLUSH) {
/* Let the FLUSH go last from the queue , do not run here to preserve ordering */
llist_add((struct llist_node *)(&pio->list), &ploop->pios[PLOOP_LIST_PREPARE]);
- return;
+ goto out;
}
ploop_prepare_one_embedded_pio(ploop, pio, &deferred_pios);
@@ -2262,7 +2242,7 @@ static void ploop_submit_embedded_pio(struct ploop *ploop, struct pio *pio)
ret = ploop_process_one_deferred_bio(ploop, spio);
current->flags = old_flags;
if (ret == 1) {
- /* not queued add back to deferreed*/
+ /* not queued add back to deferred */
llist_add((struct llist_node *)(&spio->list),
&ploop->pios[PLOOP_LIST_DEFERRED]);
} else {
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