[Devel] [RFC PATCH vz9 v4 31/33] dm-ploop: make md writeback timeout to be per page

[Alexander Atanasov]

Do not bulk write all dirtied bat pages in a common timeout.
Instead mark dirty time for each page and delay for each page
by the timeout. If page is tried to be redirtied - update the
dirty time so for hot page try to accumulate more changes before
writeout.

https://virtuozzo.atlassian.net/browse/VSTOR-91817
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c | 5 ++---
 drivers/md/dm-ploop.h     | 1 +
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index b174a94358e0..e031ce5f5f27 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -560,6 +560,7 @@ static bool ploop_md_make_dirty(struct ploop *ploop, struct md_page *md)
 
 	write_lock_irqsave(&ploop->bat_rwlock, flags);
 	WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
+	md->dirty_time = ktime_get();
 	if (!test_and_set_bit(MD_DIRTY, &md->status)) {
 		list_add(&md->wb_link, &ploop->wb_batch_list);
 		new = true;
@@ -1820,11 +1821,9 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop)
 	ktime_t ktime, ktimeout;
 	LIST_HEAD(ll_skipped);
 	struct md_page *md, *mtmp;
-	int send_all;
 
 	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
@@ -1832,7 +1831,7 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop)
 	list_for_each_entry_safe(md, mtmp, &ploop->wb_batch_list, wb_link) {
 		write_lock_irq(&ploop->bat_rwlock);
 		list_del_init(&md->wb_link);
-		if (md->high_prio || send_all) {
+		if (md->high_prio || ktime_after(md->dirty_time, ktimeout)) {
 			/* 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));
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index aceaeeeb8af3..1651293e2fd8 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -130,6 +130,7 @@ struct md_page {
 	rwlock_t lock;
 
 	bool high_prio;
+	ktime_t dirty_time;
 };
 
 enum {
-- 
2.43.0