reduce number of threads for uzfs (#47)

include/sys/zfs_context.h

@@ -654,7 +654,7 @@ extern void delay(clock_t ticks);
 	} while (0);
 
 #define	max_ncpus	64
-#define	boot_ncpus	(sysconf(_SC_NPROCESSORS_ONLN))
+#define	boot_ncpus	(MIN(sysconf(_SC_NPROCESSORS_ONLN), max_ncpus))
 
 /*
  * Process priorities as defined by setpriority(2) and getpriority(2).

lib/libzpool/taskq.c

@@ -29,6 +29,7 @@
  */
 
 #include <sys/zfs_context.h>
+#include <sys/prctl.h>
 
 int taskq_now;
 taskq_t *system_taskq;
@@ -219,6 +220,8 @@ taskq_thread(void *arg)
 	taskq_ent_t *t;
 	boolean_t prealloc;
 
+	prctl(PR_SET_NAME, tq->tq_name, 0, 0, 0);
+
 	mutex_enter(&tq->tq_lock);
 	while (tq->tq_flags & TASKQ_ACTIVE) {
 		if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
@@ -359,8 +362,8 @@ taskq_cancel_id(taskq_t *tq, taskqid_t id)
 void
 system_taskq_init(void)
 {
-	system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
-	    TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
+	system_taskq = taskq_create("system_taskq", boot_ncpus, maxclsyspri,
+	    4, 512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 	system_delay_taskq = taskq_create("delay_taskq", 4, maxclsyspri, 4,
 	    512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 }

module/zfs/arc.c

@@ -6627,8 +6627,8 @@ arc_init(void)
 	    offsetof(arc_prune_t, p_node));
 	mutex_init(&arc_prune_mtx, NULL, MUTEX_DEFAULT, NULL);
 
-	arc_prune_taskq = taskq_create("arc_prune", max_ncpus, defclsyspri,
-	    max_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
+	arc_prune_taskq = taskq_create("arc_prune", boot_ncpus, defclsyspri,
+	    boot_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
 	arc_reclaim_thread_exit = B_FALSE;
 

module/zfs/dsl_pool.c

@@ -179,8 +179,8 @@ 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, defclsyspri,
-	    max_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
+	dp->dp_iput_taskq = taskq_create("z_iput", boot_ncpus, defclsyspri,
+	    boot_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
 	return (dp);
 }

module/zfs/spa.c

@@ -143,9 +143,9 @@ static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
 const zio_taskq_info_t zio_taskqs[ZIO_TYPES][ZIO_TASKQ_TYPES] = {
 	/* ISSUE	ISSUE_HIGH	INTR		INTR_HIGH */
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* NULL */
-	{ ZTI_N(8),	ZTI_NULL,	ZTI_P(12, 8),	ZTI_NULL }, /* READ */
-	{ ZTI_BATCH,	ZTI_N(5),	ZTI_P(12, 8),	ZTI_N(5) }, /* WRITE */
-	{ ZTI_P(12, 8),	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* FREE */
+	{ ZTI_N(4),	ZTI_NULL,	ZTI_BATCH,	ZTI_NULL }, /* READ */
+	{ ZTI_BATCH,	ZTI_N(3),	ZTI_ONE,	ZTI_ONE  }, /* WRITE */
+	{ ZTI_P(2, 4),	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* FREE */
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* CLAIM */
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* IOCTL */
 };

module/zfs/txg.c

@@ -123,9 +123,9 @@ txg_init(dsl_pool_t *dp, uint64_t txg)
 	int c;
 	bzero(tx, sizeof (tx_state_t));
 
-	tx->tx_cpu = vmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
+	tx->tx_cpu = vmem_zalloc(boot_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
 
-	for (c = 0; c < max_ncpus; c++) {
+	for (c = 0; c < boot_ncpus; c++) {
 		int i;
 
 		mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
@@ -170,7 +170,7 @@ txg_fini(dsl_pool_t *dp)
 	cv_destroy(&tx->tx_quiesce_done_cv);
 	cv_destroy(&tx->tx_exit_cv);
 
-	for (c = 0; c < max_ncpus; c++) {
+	for (c = 0; c < boot_ncpus; c++) {
 		int i;
 
 		mutex_destroy(&tx->tx_cpu[c].tc_open_lock);
@@ -184,7 +184,7 @@ txg_fini(dsl_pool_t *dp)
 	if (tx->tx_commit_cb_taskq != NULL)
 		taskq_destroy(tx->tx_commit_cb_taskq);
 
-	vmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
+	vmem_free(tx->tx_cpu, boot_ncpus * sizeof (tx_cpu_t));
 
 	bzero(tx, sizeof (tx_state_t));
 }
@@ -373,7 +373,7 @@ txg_quiesce(dsl_pool_t *dp, uint64_t txg)
 	/*
 	 * Grab all tc_open_locks so nobody else can get into this txg.
 	 */
-	for (c = 0; c < max_ncpus; c++)
+	for (c = 0; c < boot_ncpus; c++)
 		mutex_enter(&tx->tx_cpu[c].tc_open_lock);
 
 	ASSERT(txg == tx->tx_open_txg);
@@ -387,7 +387,7 @@ txg_quiesce(dsl_pool_t *dp, uint64_t txg)
 	 * Now that we've incremented tx_open_txg, we can let threads
 	 * enter the next transaction group.
 	 */
-	for (c = 0; c < max_ncpus; c++)
+	for (c = 0; c < boot_ncpus; c++)
 		mutex_exit(&tx->tx_cpu[c].tc_open_lock);
 
 	spa_txg_history_set(dp->dp_spa, txg, TXG_STATE_OPEN, tx_open_time);
@@ -396,7 +396,7 @@ txg_quiesce(dsl_pool_t *dp, uint64_t txg)
 	/*
 	 * Quiesce the transaction group by waiting for everyone to txg_exit().
 	 */
-	for (c = 0; c < max_ncpus; c++) {
+	for (c = 0; c < boot_ncpus; c++) {
 		tx_cpu_t *tc = &tx->tx_cpu[c];
 		mutex_enter(&tc->tc_lock);
 		while (tc->tc_count[g] != 0)
@@ -430,7 +430,7 @@ txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
 	tx_state_t *tx = &dp->dp_tx;
 	list_t *cb_list;
 
-	for (c = 0; c < max_ncpus; c++) {
+	for (c = 0; c < boot_ncpus; c++) {
 		tx_cpu_t *tc = &tx->tx_cpu[c];
 		/*
 		 * No need to lock tx_cpu_t at this point, since this can
@@ -447,7 +447,7 @@ 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, defclsyspri, max_ncpus, max_ncpus * 2,
+			    boot_ncpus, defclsyspri, boot_ncpus, boot_ncpus * 2,
 			    TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 		}
 

module/zfs/vdev_file.c

@@ -260,8 +260,9 @@ vdev_ops_t vdev_file_ops = {
 void
 vdev_file_init(void)
 {
-	vdev_file_taskq = taskq_create("z_vdev_file", MAX(boot_ncpus, 16),
-	    minclsyspri, boot_ncpus, INT_MAX, TASKQ_DYNAMIC);
+	/* file backend is used for testing so we can safe some threads here */
+	vdev_file_taskq = taskq_create("z_vdev_file", 1,
+	    minclsyspri, MIN(boot_ncpus, 4), INT_MAX, TASKQ_DYNAMIC);
 
 	VERIFY(vdev_file_taskq);
 }