[Devel] [PATCH vz9 v1 28/63] 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 | 10 ++++------
 drivers/md/dm-ploop.h     |  1 +
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 2419d60e3ec6..40c3cb00856d 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -564,6 +564,8 @@ static bool ploop_md_make_dirty(struct ploop *ploop, struct md_page *md)
 		new = true;
 	}
 	write_unlock_irqrestore(&ploop->bat_rwlock, flags);
+	md->dirty_timeout = jiffies + ploop->md_submit_delay_ms*HZ/1000;
+
 	return new;
 }
 
@@ -1829,14 +1831,10 @@ static void ploop_process_resubmit_pios(struct ploop *ploop,
 
 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;
+	unsigned long timeout = jiffies;
 
-	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
@@ -1844,7 +1842,7 @@ 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 || time_before(md->dirty_timeout, timeout)) {
 			/* 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 02612339405c..fa2b02910296 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -129,6 +129,7 @@ struct md_page {
 	spinlock_t md_lock;
 
 	bool high_prio;
+	unsigned long dirty_timeout;
 };
 
 enum {
-- 
2.43.0