From 5268de78e1e61c828174cb2ac7d9c566a97cce69 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Mon, 8 Apr 2024 21:36:56 +0200 Subject: [PATCH] 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 Signed-off-by: Mike Snitzer --- .../admin-guide/device-mapper/dm-crypt.rst | 5 +++ drivers/md/dm-crypt.c | 37 +++++++++++++------ 2 files changed, 31 insertions(+), 11 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, - 1, devname); - else + if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags)) { cc->crypt_queue = alloc_workqueue("kcryptd/%s", - WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, + common_wq_flags | WQ_CPU_INTENSIVE, + 1, devname); + } else { + cc->crypt_queue = alloc_workqueue("kcryptd/%s", + 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,