From 0b1a428a1e2746701eff15e7680f815abeb38a95 Mon Sep 17 00:00:00 2001
From: Tim Murray <timmurray@google.com>
Date: Tue, 19 Jan 2016 16:33:27 -0800
Subject: [PATCH] dm-crypt: run in a WQ_HIGHPRI workqueue

Running dm-crypt in a standard workqueue results in IO competing for CPU
time with standard user apps, which can lead to pipeline bubbles and
seriously degraded performance. Move to a WQ_HIGHPRI workqueue to
protect against that.

bug 25392275

Change-Id: I589149a31c7b5d322fe2ed5b2476b1f6e3d5ee6f
---
 drivers/md/dm-crypt.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 5972b0662b7a..59c8dbe0b975 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1639,6 +1639,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
 	ret = -ENOMEM;
 	cc->io_queue = alloc_workqueue("kcryptd_io",
+				       WQ_HIGHPRI |
 				       WQ_NON_REENTRANT|
 				       WQ_MEM_RECLAIM,
 				       1);
@@ -1648,7 +1649,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	}
 
 	cc->crypt_queue = alloc_workqueue("kcryptd",
-					  WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM |
+					  WQ_HIGHPRI |
+					  WQ_MEM_RECLAIM |
 					  WQ_UNBOUND, num_online_cpus());
 	if (!cc->crypt_queue) {
 		ti->error = "Couldn't create kcryptd queue";