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authorMikulas Patocka <mpatocka@redhat.com>2024-04-08 22:36:56 +0300
committerMike Snitzer <snitzer@kernel.org>2024-04-16 18:34:47 +0300
commit5268de78e1e61c828174cb2ac7d9c566a97cce69 (patch)
treeffe0ac0469daeec112acb98f6f664e22187ac295
parent48ef0ba12e6b77a1ce5d09c580c38855b090ae7c (diff)
downloadlinux-5268de78e1e61c828174cb2ac7d9c566a97cce69.tar.xz
dm-crypt: add the optional "high_priority" flag
When WQ_HIGHPRI was used for the dm-crypt kcryptd workqueue it was reported that dm-crypt performs badly when the system is loaded[1]. Because of reports of audio skipping, dm-crypt stopped using WQ_HIGHPRI with commit f612b2132db5 (Revert "dm crypt: use WQ_HIGHPRI for the IO and crypt workqueues"). But it has since been determined that WQ_HIGHPRI provides improved performance (with reduced latency) for highend systems with much more resources than those laptop/desktop users which suffered from the use of WQ_HIGHPRI. As such, add an option "high_priority" that allows the use of WQ_HIGHPRI for dm-crypt's workqueues and also sets the write_thread to nice level MIN_NICE (-20). This commit makes it optional, so that normal users won't be harmed by it. [1] https://listman.redhat.com/archives/dm-devel/2023-February/053410.html Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
-rw-r--r--Documentation/admin-guide/device-mapper/dm-crypt.rst5
-rw-r--r--drivers/md/dm-crypt.c35
2 files changed, 30 insertions, 10 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-crypt.rst b/Documentation/admin-guide/device-mapper/dm-crypt.rst
index aa2d04d95df6..41f5f57f00eb 100644
--- a/Documentation/admin-guide/device-mapper/dm-crypt.rst
+++ b/Documentation/admin-guide/device-mapper/dm-crypt.rst
@@ -113,6 +113,11 @@ same_cpu_crypt
The default is to use an unbound workqueue so that encryption work
is automatically balanced between available CPUs.
+high_priority
+ Set dm-crypt workqueues and the writer thread to high priority. This
+ improves throughput and latency of dm-crypt while degrading general
+ responsiveness of the system.
+
submit_from_crypt_cpus
Disable offloading writes to a separate thread after encryption.
There are some situations where offloading write bios from the
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 9a74c6316c5d..eabc576d8d28 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -137,9 +137,9 @@ struct iv_elephant_private {
* and encrypts / decrypts at the same time.
*/
enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID,
- DM_CRYPT_SAME_CPU, DM_CRYPT_NO_OFFLOAD,
- DM_CRYPT_NO_READ_WORKQUEUE, DM_CRYPT_NO_WRITE_WORKQUEUE,
- DM_CRYPT_WRITE_INLINE };
+ DM_CRYPT_SAME_CPU, DM_CRYPT_HIGH_PRIORITY,
+ DM_CRYPT_NO_OFFLOAD, DM_CRYPT_NO_READ_WORKQUEUE,
+ DM_CRYPT_NO_WRITE_WORKQUEUE, DM_CRYPT_WRITE_INLINE };
enum cipher_flags {
CRYPT_MODE_INTEGRITY_AEAD, /* Use authenticated mode for cipher */
@@ -3134,7 +3134,7 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar
struct crypt_config *cc = ti->private;
struct dm_arg_set as;
static const struct dm_arg _args[] = {
- {0, 8, "Invalid number of feature args"},
+ {0, 9, "Invalid number of feature args"},
};
unsigned int opt_params, val;
const char *opt_string, *sval;
@@ -3161,6 +3161,8 @@ static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **ar
else if (!strcasecmp(opt_string, "same_cpu_crypt"))
set_bit(DM_CRYPT_SAME_CPU, &cc->flags);
+ else if (!strcasecmp(opt_string, "high_priority"))
+ set_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags);
else if (!strcasecmp(opt_string, "submit_from_crypt_cpus"))
set_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags);
@@ -3232,6 +3234,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
const char *devname = dm_table_device_name(ti->table);
int key_size;
unsigned int align_mask;
+ unsigned int common_wq_flags;
unsigned long long tmpll;
int ret;
size_t iv_size_padding, additional_req_size;
@@ -3399,19 +3402,25 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
ret = -ENOMEM;
- cc->io_queue = alloc_workqueue("kcryptd_io/%s", WQ_MEM_RECLAIM, 1, devname);
+ common_wq_flags = WQ_MEM_RECLAIM;
+ if (test_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags))
+ common_wq_flags |= WQ_HIGHPRI;
+
+ cc->io_queue = alloc_workqueue("kcryptd_io/%s", common_wq_flags, 1, devname);
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/%s", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM,
+ if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags)) {
+ cc->crypt_queue = alloc_workqueue("kcryptd/%s",
+ common_wq_flags | WQ_CPU_INTENSIVE,
1, devname);
- else
+ } else {
cc->crypt_queue = alloc_workqueue("kcryptd/%s",
- WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND,
+ common_wq_flags | WQ_CPU_INTENSIVE | WQ_UNBOUND,
num_online_cpus(), devname);
+ }
if (!cc->crypt_queue) {
ti->error = "Couldn't create kcryptd queue";
goto bad;
@@ -3427,6 +3436,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->error = "Couldn't spawn write thread";
goto bad;
}
+ if (test_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags))
+ set_user_nice(cc->write_thread, MIN_NICE);
ti->num_flush_bios = 1;
ti->limit_swap_bios = true;
@@ -3547,6 +3558,7 @@ static void crypt_status(struct dm_target *ti, status_type_t type,
num_feature_args += !!ti->num_discard_bios;
num_feature_args += test_bit(DM_CRYPT_SAME_CPU, &cc->flags);
+ num_feature_args += test_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags);
num_feature_args += test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags);
num_feature_args += test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags);
num_feature_args += test_bit(DM_CRYPT_NO_WRITE_WORKQUEUE, &cc->flags);
@@ -3560,6 +3572,8 @@ static void crypt_status(struct dm_target *ti, status_type_t type,
DMEMIT(" allow_discards");
if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags))
DMEMIT(" same_cpu_crypt");
+ if (test_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags))
+ DMEMIT(" high_priority");
if (test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags))
DMEMIT(" submit_from_crypt_cpus");
if (test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags))
@@ -3579,6 +3593,7 @@ static void crypt_status(struct dm_target *ti, status_type_t type,
DMEMIT_TARGET_NAME_VERSION(ti->type);
DMEMIT(",allow_discards=%c", ti->num_discard_bios ? 'y' : 'n');
DMEMIT(",same_cpu_crypt=%c", test_bit(DM_CRYPT_SAME_CPU, &cc->flags) ? 'y' : 'n');
+ DMEMIT(",high_priority=%c", test_bit(DM_CRYPT_HIGH_PRIORITY, &cc->flags) ? 'y' : 'n');
DMEMIT(",submit_from_crypt_cpus=%c", test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags) ?
'y' : 'n');
DMEMIT(",no_read_workqueue=%c", test_bit(DM_CRYPT_NO_READ_WORKQUEUE, &cc->flags) ?
@@ -3706,7 +3721,7 @@ static void crypt_io_hints(struct dm_target *ti, struct queue_limits *limits)
static struct target_type crypt_target = {
.name = "crypt",
- .version = {1, 25, 0},
+ .version = {1, 26, 0},
.module = THIS_MODULE,
.ctr = crypt_ctr,
.dtr = crypt_dtr,