dm crypt: use WQ_HIGHPRI for the IO and crypt workqueues

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

Signed-off-by: Tim Murray <timmurray@google.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index bb2e747907b089acb4c1e50d843615b56eab7d6f..64c5022449ee44ebd7b80ee2bac235ae4c298ed0 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2749,16 +2749,17 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
        }
 
        ret = -ENOMEM;
-       cc->io_queue = alloc_workqueue("kcryptd_io", WQ_MEM_RECLAIM, 1);
+       cc->io_queue = alloc_workqueue("kcryptd_io", WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 1);
        if (!cc->io_queue) {
                ti->error = "Couldn't create kcryptd io queue";
                goto bad;
        }
 
        if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags))
-               cc->crypt_queue = alloc_workqueue("kcryptd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 1);
+               cc->crypt_queue = alloc_workqueue("kcryptd", WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 1);
        else
-               cc->crypt_queue = alloc_workqueue("kcryptd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND,
+               cc->crypt_queue = alloc_workqueue("kcryptd",
+                                                 WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND,
                                                  num_online_cpus());
        if (!cc->crypt_queue) {
                ti->error = "Couldn't create kcryptd queue";