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dm writecache: have ssd writeback wait if the kcopyd workqueue is busy

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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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2021-06-15 14:17:35 -04:00 committed by Mike Snitzer
parent 8c77f1cb84
commit 293128b1ef
3 changed files with 12 additions and 0 deletions
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6
drivers/md/dm-kcopyd.c
View file

@ -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);

5
drivers/md/dm-writecache.c
View file

@ -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)) {

1
include/linux/dm-kcopyd.h
View file

@ -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