Add defclsyspri macro

Add a new defclsyspri macro which can be used to request the default
Linux scheduler priority.  Neither the minclsyspri or maxclsyspri map
to the default Linux kernel thread priority.  This makes it awkward to
create taskqs which run with the same priority as the rest of the kernel
threads on the system which can lead to performance issues.

All SPL callers which previously used minclsyspri or maxclsyspri have
been changed to use defclsyspri.  The vast majority of callers were
part of the test suite which won't have an external impact.  The few
places where it could impact performance the change was from maxclsyspri
to defclsyspri.  This makes it more likely the process will be scheduled
which may help performance.

To facilitate further performance analysis the spl_taskq_thread_priority
module option has been added.  When disabled (0) all newly created kernel
threads will use the default kernel thread priority.  When enabled (1)
the specified taskq priority will be used.  By default this value is
enabled (1).

Signed-off-by: Brian Behlendorf <[email protected]>

8 files changed, 31 insertions, 24 deletions

diff --git a/module/spl/spl-kmem-cache.c b/module/spl/spl-kmem-cache.c
index 86c26ff05..112d0f876 100644
--- a/module/spl/spl-kmem-cache.c
+++ b/module/spl/spl-kmem-cache.c
@@ -1725,7 +1725,7 @@ spl_kmem_cache_init(void)
 	init_rwsem(&spl_kmem_cache_sem);
 	INIT_LIST_HEAD(&spl_kmem_cache_list);
 	spl_kmem_cache_taskq = taskq_create("spl_kmem_cache",
-	    spl_kmem_cache_kmem_threads, maxclsyspri,
+	    spl_kmem_cache_kmem_threads, defclsyspri,
 	    spl_kmem_cache_kmem_threads * 8, INT_MAX,
 	    TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 	spl_register_shrinker(&spl_kmem_cache_shrinker);
diff --git a/module/spl/spl-taskq.c b/module/spl/spl-taskq.c
index 44799de1d..b4282333e 100644
--- a/module/spl/spl-taskq.c
+++ b/module/spl/spl-taskq.c
@@ -36,6 +36,11 @@ int spl_taskq_thread_dynamic = 1;
 module_param(spl_taskq_thread_dynamic, int, 0644);
 MODULE_PARM_DESC(spl_taskq_thread_dynamic, "Allow dynamic taskq threads");
 
+int spl_taskq_thread_priority = 1;
+module_param(spl_taskq_thread_priority, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_priority,
+    "Allow non-default priority for taskq threads");
+
 int spl_taskq_thread_sequential = 4;
 module_param(spl_taskq_thread_sequential, int, 0644);
 MODULE_PARM_DESC(spl_taskq_thread_sequential,
@@ -913,7 +918,9 @@ taskq_thread_create(taskq_t *tq)
 		kthread_bind(tqt->tqt_thread, last_used_cpu);
 	}
 
-	set_user_nice(tqt->tqt_thread, PRIO_TO_NICE(tq->tq_pri));
+	if (spl_taskq_thread_priority)
+		set_user_nice(tqt->tqt_thread, PRIO_TO_NICE(tq->tq_pri));
+
 	wake_up_process(tqt->tqt_thread);
 
 	return (tqt);
@@ -1070,12 +1077,12 @@ int
 spl_taskq_init(void)
 {
 	system_taskq = taskq_create("spl_system_taskq", MAX(boot_ncpus, 64),
-	    minclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE|TASKQ_DYNAMIC);
+	    defclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE|TASKQ_DYNAMIC);
 	if (system_taskq == NULL)
 		return (1);
 
 	dynamic_taskq = taskq_create("spl_dynamic_taskq", 1,
-	    minclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE);
+	    defclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE);
 	if (dynamic_taskq == NULL) {
 		taskq_destroy(system_taskq);
 		return (1);
diff --git a/module/splat/splat-atomic.c b/module/splat/splat-atomic.c
index e94f42f00..999f4f058 100644
--- a/module/splat/splat-atomic.c
+++ b/module/splat/splat-atomic.c
@@ -156,7 +156,7 @@ splat_atomic_test1(struct file *file, void *arg)
 
 		thr = (kthread_t *)thread_create(NULL, 0, splat_atomic_work,
 						 &ap, 0, &p0, TS_RUN,
-						 minclsyspri);
+						 defclsyspri);
 		if (thr == NULL) {
 			rc = -ESRCH;
 			mutex_exit(&ap.ap_lock);
diff --git a/module/splat/splat-kmem.c b/module/splat/splat-kmem.c
index cd0000bae..b3fd1a84d 100644
--- a/module/splat/splat-kmem.c
+++ b/module/splat/splat-kmem.c
@@ -739,7 +739,7 @@ splat_kmem_cache_thread_test(struct file *file, void *arg, char *name,
 	for (i = 0; i < SPLAT_KMEM_THREADS; i++) {
 		thr = thread_create(NULL, 0,
 				    splat_kmem_cache_test_thread,
-				    kcp, 0, &p0, TS_RUN, minclsyspri);
+				    kcp, 0, &p0, TS_RUN, defclsyspri);
 		if (thr == NULL) {
 			rc = -ESRCH;
 			goto out_cache;
diff --git a/module/splat/splat-mutex.c b/module/splat/splat-mutex.c
index 909d730cb..86bef8ee3 100644
--- a/module/splat/splat-mutex.c
+++ b/module/splat/splat-mutex.c
@@ -87,7 +87,7 @@ splat_mutex_test1(struct file *file, void *arg)
         if (mp == NULL)
                 return -ENOMEM;
 
-        tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, 1, maxclsyspri,
+        tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, 1, defclsyspri,
                           50, INT_MAX, TASKQ_PREPOPULATE);
         if (tq == NULL) {
                 rc = -ENOMEM;
@@ -196,7 +196,7 @@ splat_mutex_test2(struct file *file, void *arg)
 
         /* Create several threads allowing tasks to race with each other */
         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, num_online_cpus(),
-                          maxclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
+                          defclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
         if (tq == NULL) {
                 rc = -ENOMEM;
                 goto out;
@@ -266,7 +266,7 @@ splat_mutex_test3(struct file *file, void *arg)
         mp.mp_file = file;
         mutex_init(&mp.mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 
-        if ((tq = taskq_create(SPLAT_MUTEX_TEST_NAME, 1, maxclsyspri,
+        if ((tq = taskq_create(SPLAT_MUTEX_TEST_NAME, 1, defclsyspri,
                                50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Taskq '%s' "
                              "create failed\n", SPLAT_MUTEX_TEST3_NAME);
diff --git a/module/splat/splat-rwlock.c b/module/splat/splat-rwlock.c
index 6c623792e..284f77370 100644
--- a/module/splat/splat-rwlock.c
+++ b/module/splat/splat-rwlock.c
@@ -327,7 +327,7 @@ splat_rwlock_test2(struct file *file, void *arg)
 
 	/* Create several threads allowing tasks to race with each other */
 	tq = taskq_create(SPLAT_RWLOCK_TEST_TASKQ, num_online_cpus(),
-			  maxclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
+			  defclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
 	if (tq == NULL) {
 		rc = -ENOMEM;
 		goto out;
@@ -500,7 +500,7 @@ splat_rwlock_test4(struct file *file, void *arg)
 	if (rwp == NULL)
 		return -ENOMEM;
 
-	tq = taskq_create(SPLAT_RWLOCK_TEST_TASKQ, 1, maxclsyspri,
+	tq = taskq_create(SPLAT_RWLOCK_TEST_TASKQ, 1, defclsyspri,
 			  50, INT_MAX, TASKQ_PREPOPULATE);
 	if (tq == NULL) {
 		rc = -ENOMEM;
diff --git a/module/splat/splat-taskq.c b/module/splat/splat-taskq.c
index 645bc9145..8f06f413d 100644
--- a/module/splat/splat-taskq.c
+++ b/module/splat/splat-taskq.c
@@ -134,7 +134,7 @@ splat_taskq_test1_impl(struct file *file, void *arg, boolean_t prealloc)
 		     "Taskq '%s' creating (%s dispatch)\n",
 	             SPLAT_TASKQ_TEST1_NAME,
 		     prealloc ? "prealloc" : "dynamic");
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST1_NAME, 1, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST1_NAME, 1, defclsyspri,
 			       50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST1_NAME,
 		           "Taskq '%s' create failed\n",
@@ -269,7 +269,7 @@ splat_taskq_test2_impl(struct file *file, void *arg, boolean_t prealloc) {
 			     prealloc ? "prealloc" : "dynamic");
 		if ((tq[i] = taskq_create(SPLAT_TASKQ_TEST2_NAME,
 			                  TEST2_THREADS_PER_TASKQ,
-					  maxclsyspri, 50, INT_MAX,
+					  defclsyspri, 50, INT_MAX,
 					  TASKQ_PREPOPULATE)) == NULL) {
 			splat_vprint(file, SPLAT_TASKQ_TEST2_NAME,
 			           "Taskq '%s/%d' create failed\n",
@@ -494,7 +494,7 @@ splat_taskq_test4_common(struct file *file, void *arg, int minalloc,
 		     SPLAT_TASKQ_TEST4_NAME,
 		     prealloc ? "prealloc" : "dynamic",
 		     minalloc, maxalloc, nr_tasks);
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST4_NAME, 1, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST4_NAME, 1, defclsyspri,
 		               minalloc, maxalloc, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST4_NAME,
 		             "Taskq '%s' create failed\n",
@@ -712,7 +712,7 @@ splat_taskq_test5_impl(struct file *file, void *arg, boolean_t prealloc)
 		     "Taskq '%s' creating (%s dispatch)\n",
 		     SPLAT_TASKQ_TEST5_NAME,
 		     prealloc ? "prealloc" : "dynamic");
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST5_NAME, 3, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST5_NAME, 3, defclsyspri,
 		               50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST5_NAME,
 		             "Taskq '%s' create failed\n",
@@ -873,7 +873,7 @@ splat_taskq_test6_impl(struct file *file, void *arg, boolean_t prealloc)
 		     "Taskq '%s' creating (%s dispatch)\n",
 		     SPLAT_TASKQ_TEST6_NAME,
 		     prealloc ? "prealloc" : "dynamic");
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST6_NAME, 3, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST6_NAME, 3, defclsyspri,
 		               50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST6_NAME,
 		             "Taskq '%s' create failed\n",
@@ -1005,7 +1005,7 @@ splat_taskq_test7_impl(struct file *file, void *arg, boolean_t prealloc)
 	             "Taskq '%s' creating (%s dispatch)\n",
 	             SPLAT_TASKQ_TEST7_NAME,
 	             prealloc ? "prealloc" :  "dynamic");
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST7_NAME, 1, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST7_NAME, 1, defclsyspri,
 	                       50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST7_NAME,
 		             "Taskq '%s' create failed\n",
@@ -1094,7 +1094,7 @@ splat_taskq_throughput(struct file *file, void *arg, const char *name,
 
 	splat_vprint(file, name, "Taskq '%s' creating (%d/%d/%d/%d)\n",
 	    name, nthreads, minalloc, maxalloc, tasks);
-	if ((tq = taskq_create(name, nthreads, maxclsyspri,
+	if ((tq = taskq_create(name, nthreads, defclsyspri,
 	    minalloc, maxalloc, flags)) == NULL) {
 		splat_vprint(file, name, "Taskq '%s' create failed\n", name);
 		rc = -EINVAL;
@@ -1203,7 +1203,7 @@ splat_taskq_test9(struct file *file, void *arg)
 	splat_vprint(file, SPLAT_TASKQ_TEST9_NAME,
 	    "Taskq '%s' creating (%s dispatch) (%d/%d/%d)\n",
 	    SPLAT_TASKQ_TEST9_NAME, "delay", minalloc, maxalloc, nr_tasks);
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST9_NAME, 3, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST9_NAME, 3, defclsyspri,
 	    minalloc, maxalloc, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST9_NAME,
 		    "Taskq '%s' create failed\n", SPLAT_TASKQ_TEST9_NAME);
@@ -1303,7 +1303,7 @@ splat_taskq_test10(struct file *file, void *arg)
 	splat_vprint(file, SPLAT_TASKQ_TEST10_NAME,
 	    "Taskq '%s' creating (%s dispatch) (%d/%d/%d)\n",
 	    SPLAT_TASKQ_TEST10_NAME, "delay", minalloc, maxalloc, nr_tasks);
-	if ((tq = taskq_create(SPLAT_TASKQ_TEST10_NAME, 3, maxclsyspri,
+	if ((tq = taskq_create(SPLAT_TASKQ_TEST10_NAME, 3, defclsyspri,
 	    minalloc, maxalloc, TASKQ_PREPOPULATE)) == NULL) {
 		splat_vprint(file, SPLAT_TASKQ_TEST10_NAME,
 		    "Taskq '%s' create failed\n", SPLAT_TASKQ_TEST10_NAME);
diff --git a/module/splat/splat-thread.c b/module/splat/splat-thread.c
index 3255e37e5..8a4471407 100644
--- a/module/splat/splat-thread.c
+++ b/module/splat/splat-thread.c
@@ -112,7 +112,7 @@ splat_thread_test1(struct file *file, void *arg)
 	tp.tp_rc = 0;
 
 	thr = (kthread_t *)thread_create(NULL, 0, splat_thread_work1, &tp, 0,
-			                 &p0, TS_RUN, minclsyspri);
+			                 &p0, TS_RUN, defclsyspri);
 	/* Must never fail under Solaris, but we check anyway since this
 	 * can happen in the linux SPL, we may want to change this behavior */
 	if (thr == NULL)
@@ -161,7 +161,7 @@ splat_thread_test2(struct file *file, void *arg)
 	tp.tp_rc = 0;
 
 	thr = (kthread_t *)thread_create(NULL, 0, splat_thread_work2, &tp, 0,
-			                 &p0, TS_RUN, minclsyspri);
+			                 &p0, TS_RUN, defclsyspri);
 	/* Must never fail under Solaris, but we check anyway since this
 	 * can happen in the linux SPL, we may want to change this behavior */
 	if (thr == NULL)
@@ -278,7 +278,7 @@ splat_thread_test3(struct file *file, void *arg)
 	/* Start tsd wait threads */
 	for (i = 0; i < SPLAT_THREAD_TEST_THREADS; i++) {
 		if (thread_create(NULL, 0, splat_thread_work3_wait,
-				  &tp, 0, &p0, TS_RUN, minclsyspri))
+				  &tp, 0, &p0, TS_RUN, defclsyspri))
 			wait_count++;
 	}
 
@@ -295,7 +295,7 @@ splat_thread_test3(struct file *file, void *arg)
 	/* Start tsd exit threads */
 	for (i = 0; i < SPLAT_THREAD_TEST_THREADS; i++) {
 		if (thread_create(NULL, 0, splat_thread_work3_exit,
-				  &tp, 0, &p0, TS_RUN, minclsyspri))
+				  &tp, 0, &p0, TS_RUN, defclsyspri))
 			exit_count++;
 	}