From 293128b1ef5ae2cfa7403d54e183fe689ed5d303 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Tue, 15 Jun 2021 14:17:35 -0400 Subject: [PATCH] dm writecache: have ssd writeback wait if the kcopyd workqueue is busy Make dm-writecache wait if the kcopyd workqueue is busy (as will happen if waiting for page allocation or inside submit_bio). This change improves performance of "mkfs.ext2" by approximately 20% on one testbed. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer --- drivers/md/dm-kcopyd.c | 6 ++++++ drivers/md/dm-writecache.c | 5 +++++ include/linux/dm-kcopyd.h | 1 + 3 files changed, 12 insertions(+) diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c index e50625ce74ec5..37b03ab7e5c9e 100644 --- a/drivers/md/dm-kcopyd.c +++ b/drivers/md/dm-kcopyd.c @@ -980,3 +980,9 @@ void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc) kfree(kc); } EXPORT_SYMBOL(dm_kcopyd_client_destroy); + +void dm_kcopyd_client_flush(struct dm_kcopyd_client *kc) +{ + flush_workqueue(kc->kcopyd_wq); +} +EXPORT_SYMBOL(dm_kcopyd_client_flush); diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index 56179a21db0ea..28bb6890fcf43 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -1812,6 +1812,11 @@ static void writecache_writeback(struct work_struct *work) struct writeback_list wbl; unsigned long n_walked; + if (!WC_MODE_PMEM(wc)) { + /* Wait for any active kcopyd work on behalf of ssd writeback */ + dm_kcopyd_client_flush(wc->dm_kcopyd); + } + wc_lock(wc); restart: if (writecache_has_error(wc)) { diff --git a/include/linux/dm-kcopyd.h b/include/linux/dm-kcopyd.h index e42de7750c884..c1707ee5b5408 100644 --- a/include/linux/dm-kcopyd.h +++ b/include/linux/dm-kcopyd.h @@ -51,6 +51,7 @@ MODULE_PARM_DESC(name, description) struct dm_kcopyd_client; struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle); void dm_kcopyd_client_destroy(struct dm_kcopyd_client *kc); +void dm_kcopyd_client_flush(struct dm_kcopyd_client *kc); /* * Submit a copy job to kcopyd. This is built on top of the