Align thread priority with Linux defaults

include/sys/zfs_context.h

@@ -233,6 +233,7 @@ typedef struct kthread {
 	kt_did_t	t_tid;
 	thread_func_t	t_func;
 	void *		t_arg;
+	pri_t		t_pri;
 } kthread_t;
 
 #define	curthread			zk_thread_current()
@@ -615,8 +616,12 @@ extern void delay(clock_t ticks);
 #define	max_ncpus	64
 #define	boot_ncpus	(sysconf(_SC_NPROCESSORS_ONLN))
 
-#define	minclsyspri	60
-#define	maxclsyspri	99
+/*
+ * Process priorities as defined by setpriority(2) and getpriority(2).
+ */
+#define	minclsyspri	19
+#define	maxclsyspri	-20
+#define	defclsyspri	0
 
 #define	CPU_SEQID	(pthread_self() & (max_ncpus - 1))
 

lib/libzpool/kernel.c

@@ -128,6 +128,7 @@ zk_thread_helper(void *arg)
 	VERIFY3S(pthread_mutex_lock(&kthread_lock), ==, 0);
 	kthread_nr++;
 	VERIFY3S(pthread_mutex_unlock(&kthread_lock), ==, 0);
+	(void) setpriority(PRIO_PROCESS, 0, kt->t_pri);
 
 	kt->t_tid = pthread_self();
 	((thread_func_arg_t) kt->t_func)(kt->t_arg);
@@ -151,6 +152,7 @@ zk_thread_create(caddr_t stk, size_t stksize, thread_func_t func, void *arg,
 	kt = umem_zalloc(sizeof (kthread_t), UMEM_NOFAIL);
 	kt->t_func = func;
 	kt->t_arg = arg;
+	kt->t_pri = pri;
 
 	VERIFY0(pthread_attr_init(&attr));
 	VERIFY0(pthread_attr_setdetachstate(&attr, detachstate));

lib/libzpool/taskq.c

@@ -308,7 +308,7 @@ taskq_create(const char *name, int nthreads, pri_t pri,
 
 	for (t = 0; t < nthreads; t++)
 		VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
-		    taskq_thread, tq, TS_RUN, NULL, 0, 0)) != NULL);
+		    taskq_thread, tq, TS_RUN, NULL, 0, pri)) != NULL);
 
 	return (tq);
 }
@@ -371,7 +371,7 @@ taskq_cancel_id(taskq_t *tq, taskqid_t id)
 void
 system_taskq_init(void)
 {
-	system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
+	system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
 	    TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 }
 

module/zfs/arc.c

@@ -5431,7 +5431,7 @@ arc_init(void)
 	mutex_init(&arc_prune_mtx, NULL, MUTEX_DEFAULT, NULL);
 	bzero(&arc_eviction_hdr, sizeof (arc_buf_hdr_t));
 
-	arc_prune_taskq = taskq_create("arc_prune", max_ncpus, minclsyspri,
+	arc_prune_taskq = taskq_create("arc_prune", max_ncpus, defclsyspri,
 	    max_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
 	arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED,
@@ -5444,10 +5444,10 @@ arc_init(void)
 	}
 
 	(void) thread_create(NULL, 0, arc_reclaim_thread, NULL, 0, &p0,
-	    TS_RUN, minclsyspri);
+	    TS_RUN, defclsyspri);
 
 	(void) thread_create(NULL, 0, arc_user_evicts_thread, NULL, 0, &p0,
-	    TS_RUN, minclsyspri);
+	    TS_RUN, defclsyspri);
 
 	arc_dead = FALSE;
 	arc_warm = B_FALSE;
@@ -6954,7 +6954,7 @@ l2arc_start(void)
 		return;
 
 	(void) thread_create(NULL, 0, l2arc_feed_thread, NULL, 0, &p0,
-	    TS_RUN, minclsyspri);
+	    TS_RUN, defclsyspri);
 }
 
 void

module/zfs/dbuf.c

@@ -413,7 +413,7 @@ dbuf_init(void)
 	 * All entries are queued via taskq_dispatch_ent(), so min/maxalloc
 	 * configuration is not required.
 	 */
-	dbu_evict_taskq = taskq_create("dbu_evict", 1, minclsyspri, 0, 0, 0);
+	dbu_evict_taskq = taskq_create("dbu_evict", 1, defclsyspri, 0, 0, 0);
 }
 
 void

module/zfs/dmu_objset.c

@@ -1839,7 +1839,7 @@ dmu_objset_find_dp(dsl_pool_t *dp, uint64_t ddobj,
 	ntasks = dmu_find_threads;
 	if (ntasks == 0)
 		ntasks = vdev_count_leaves(dp->dp_spa) * 4;
-	tq = taskq_create("dmu_objset_find", ntasks, minclsyspri, ntasks,
+	tq = taskq_create("dmu_objset_find", ntasks, maxclsyspri, ntasks,
 	    INT_MAX, 0);
 	if (tq == NULL) {
 		kmem_free(dcp, sizeof (*dcp));

module/zfs/dsl_pool.c

@@ -170,7 +170,7 @@ dsl_pool_open_impl(spa_t *spa, uint64_t txg)
 	mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
 	cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
 
-	dp->dp_iput_taskq = taskq_create("z_iput", max_ncpus, minclsyspri,
+	dp->dp_iput_taskq = taskq_create("z_iput", max_ncpus, defclsyspri,
 	    max_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
 	return (dp);

module/zfs/metaslab.c

@@ -492,7 +492,7 @@ metaslab_group_create(metaslab_class_t *mc, vdev_t *vd)
 	mg->mg_activation_count = 0;
 
 	mg->mg_taskq = taskq_create("metaslab_group_taskq", metaslab_load_pct,
-	    minclsyspri, 10, INT_MAX, TASKQ_THREADS_CPU_PCT | TASKQ_DYNAMIC);
+	    maxclsyspri, 10, INT_MAX, TASKQ_THREADS_CPU_PCT | TASKQ_DYNAMIC);
 
 	return (mg);
 }

module/zfs/spa.c

@@ -898,11 +898,13 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
 			pri_t pri = maxclsyspri;
 			/*
 			 * The write issue taskq can be extremely CPU
-			 * intensive.  Run it at slightly lower priority
-			 * than the other taskqs.
+			 * intensive.  Run it at slightly less important
+			 * priority than the other taskqs.  Under Linux this
+			 * means incrementing the priority value on platforms
+			 * like illumos it should be decremented.
 			 */
 			if (t == ZIO_TYPE_WRITE && q == ZIO_TASKQ_ISSUE)
-				pri--;
+				pri++;
 
 			tq = taskq_create_proc(name, value, pri, 50,
 			    INT_MAX, spa->spa_proc, flags);

module/zfs/txg.c

@@ -205,15 +205,15 @@ txg_sync_start(dsl_pool_t *dp)
 	tx->tx_threads = 2;
 
 	tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
-	    dp, 0, &p0, TS_RUN, minclsyspri);
+	    dp, 0, &p0, TS_RUN, defclsyspri);
 
 	/*
 	 * The sync thread can need a larger-than-default stack size on
 	 * 32-bit x86.  This is due in part to nested pools and
 	 * scrub_visitbp() recursion.
 	 */
 	tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread,
-	    dp, 0, &p0, TS_RUN, minclsyspri);
+	    dp, 0, &p0, TS_RUN, defclsyspri);
 
 	mutex_exit(&tx->tx_sync_lock);
 }
@@ -445,7 +445,7 @@ txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
 			 * Commit callback taskq hasn't been created yet.
 			 */
 			tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
-			    max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
+			    max_ncpus, defclsyspri, max_ncpus, max_ncpus * 2,
 			    TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 		}
 

module/zfs/zfs_ctldir.c

@@ -1009,7 +1009,7 @@ zfsctl_shares_lookup(struct inode *dip, char *name, struct inode **ipp,
 void
 zfsctl_init(void)
 {
-	zfs_expire_taskq = taskq_create("z_unmount", 1, maxclsyspri,
+	zfs_expire_taskq = taskq_create("z_unmount", 1, defclsyspri,
 	    1, 8, TASKQ_PREPOPULATE);
 }
 

module/zfs/zil.c

@@ -1888,7 +1888,7 @@ zil_open(objset_t *os, zil_get_data_t *get_data)
 	ASSERT(list_is_empty(&zilog->zl_lwb_list));
 
 	zilog->zl_get_data = get_data;
-	zilog->zl_clean_taskq = taskq_create("zil_clean", 1, minclsyspri,
+	zilog->zl_clean_taskq = taskq_create("zil_clean", 1, defclsyspri,
 	    2, 2, TASKQ_PREPOPULATE);
 
 	return (zilog);