From: Witold Kręcicki <wpk@isc.org>
Date: Fri, 23 Nov 2018 11:15:50 +0000 (+0000)
Subject: Make task quantum dynamic: smaller if there are more tasks waiting.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=91788ada319847d87d05349616ea03585ff6459e;p=thirdparty%2Fbind9.git

Make task quantum dynamic: smaller if there are more tasks waiting.
---

diff --git a/bin/delv/delv.c b/bin/delv/delv.c
index 8754d1b328d..658400b88a7 100644
--- a/bin/delv/delv.c
+++ b/bin/delv/delv.c
@@ -1623,7 +1623,7 @@ main(int argc, char *argv[]) {
 		fatal("failed to create mctx");
 
 	CHECK(isc_appctx_create(mctx, &actx));
-	CHECK(isc_taskmgr_createinctx(mctx, actx, 1, 0, &taskmgr));
+	CHECK(isc_taskmgr_createinctx(mctx, actx, 1, &taskmgr));
 	CHECK(isc_socketmgr_createinctx(mctx, actx, &socketmgr));
 	CHECK(isc_timermgr_createinctx(mctx, actx, &timermgr));
 
diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index 2b6cab552e8..d588c910b18 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -1363,7 +1363,7 @@ setup_libs(void) {
 
 	isc_log_setdebuglevel(lctx, 0);
 
-	result = isc_taskmgr_create(mctx, 1, 0, &taskmgr);
+	result = isc_taskmgr_create(mctx, 1, &taskmgr);
 	check_result(result, "isc_taskmgr_create");
 
 	result = isc_task_create(taskmgr, 0, &global_task);
diff --git a/bin/dnssec/dnssec-signzone.c b/bin/dnssec/dnssec-signzone.c
index 7e2e6c67c1c..0dc23bded5c 100644
--- a/bin/dnssec/dnssec-signzone.c
+++ b/bin/dnssec/dnssec-signzone.c
@@ -3853,7 +3853,7 @@ main(int argc, char *argv[]) {
 	print_time(outfp);
 	print_version(outfp);
 
-	result = isc_taskmgr_create(mctx, ntasks, 0, &taskmgr);
+	result = isc_taskmgr_create(mctx, ntasks, &taskmgr);
 	if (result != ISC_R_SUCCESS)
 		fatal("failed to create task manager: %s",
 		      isc_result_totext(result));
diff --git a/bin/named/main.c b/bin/named/main.c
index 7c1d1fa6f1d..15f048e04d1 100644
--- a/bin/named/main.c
+++ b/bin/named/main.c
@@ -803,7 +803,7 @@ create_managers(void) {
 		      "using %u UDP listener%s per interface",
 		      named_g_udpdisp, named_g_udpdisp == 1 ? "" : "s");
 
-	result = isc_taskmgr_create(named_g_mctx, named_g_cpus, 0,
+	result = isc_taskmgr_create(named_g_mctx, named_g_cpus,
 				    &named_g_taskmgr);
 	if (result != ISC_R_SUCCESS) {
 		UNEXPECTED_ERROR(__FILE__, __LINE__,
diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index 7ffba6be547..5d2ed676395 100644
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@@ -885,7 +885,7 @@ setup_system(void) {
 	result = isc_timermgr_create(gmctx, &timermgr);
 	check_result(result, "dns_timermgr_create");
 
-	result = isc_taskmgr_create(gmctx, 1, 0, &taskmgr);
+	result = isc_taskmgr_create(gmctx, 1, &taskmgr);
 	check_result(result, "isc_taskmgr_create");
 
 	result = isc_task_create(taskmgr, 0, &global_task);
diff --git a/bin/rndc/rndc.c b/bin/rndc/rndc.c
index 48682de9db2..497efe2e62f 100644
--- a/bin/rndc/rndc.c
+++ b/bin/rndc/rndc.c
@@ -934,7 +934,7 @@ main(int argc, char **argv) {
 
 	DO("create memory context", isc_mem_create(0, 0, &rndc_mctx));
 	DO("create socket manager", isc_socketmgr_create(rndc_mctx, &socketmgr));
-	DO("create task manager", isc_taskmgr_create(rndc_mctx, 1, 0, &taskmgr));
+	DO("create task manager", isc_taskmgr_create(rndc_mctx, 1, &taskmgr));
 	DO("create task", isc_task_create(taskmgr, 0, &task));
 
 	DO("create logging context", isc_log_create(rndc_mctx, &log, &logconfig));
diff --git a/bin/tests/optional/adb_test.c b/bin/tests/optional/adb_test.c
index 8eeef45a473..d36c00f8964 100644
--- a/bin/tests/optional/adb_test.c
+++ b/bin/tests/optional/adb_test.c
@@ -146,7 +146,7 @@ create_managers(void) {
 	isc_result_t result;
 
 	taskmgr = NULL;
-	result = isc_taskmgr_create(mctx, 5, 0, &taskmgr);
+	result = isc_taskmgr_create(mctx, 5, &taskmgr);
 	check_result(result, "isc_taskmgr_create");
 
 	timermgr = NULL;
diff --git a/bin/tests/optional/byaddr_test.c b/bin/tests/optional/byaddr_test.c
index 05e6c5ded31..2670a9077a9 100644
--- a/bin/tests/optional/byaddr_test.c
+++ b/bin/tests/optional/byaddr_test.c
@@ -114,7 +114,7 @@ main(int argc, char *argv[]) {
 	}
 
 	taskmgr = NULL;
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, 0, &taskmgr)
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, &taskmgr)
 		      == ISC_R_SUCCESS);
 	task = NULL;
 	RUNTIME_CHECK(isc_task_create(taskmgr, 0, &task)
diff --git a/bin/tests/optional/byname_test.c b/bin/tests/optional/byname_test.c
index c48baec0bd1..f4658aff472 100644
--- a/bin/tests/optional/byname_test.c
+++ b/bin/tests/optional/byname_test.c
@@ -228,7 +228,7 @@ main(int argc, char *argv[]) {
 	}
 
 	taskmgr = NULL;
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, 0, &taskmgr) ==
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, &taskmgr) ==
 		      ISC_R_SUCCESS);
 	task = NULL;
 	RUNTIME_CHECK(isc_task_create(taskmgr, 0, &task) ==
diff --git a/bin/tests/optional/gsstest.c b/bin/tests/optional/gsstest.c
index badb346609a..d09daca806d 100644
--- a/bin/tests/optional/gsstest.c
+++ b/bin/tests/optional/gsstest.c
@@ -472,7 +472,7 @@ main(int argc, char *argv[]) {
 	RUNCHECK(dst_lib_init(mctx, NULL));
 
 	taskmgr = NULL;
-	RUNCHECK(isc_taskmgr_create(mctx, 1, 0, &taskmgr));
+	RUNCHECK(isc_taskmgr_create(mctx, 1, &taskmgr));
 	task = NULL;
 	RUNCHECK(isc_task_create(taskmgr, 0, &task));
 	timermgr = NULL;
diff --git a/bin/tests/optional/ratelimiter_test.c b/bin/tests/optional/ratelimiter_test.c
index 02eadace526..a405e05df45 100644
--- a/bin/tests/optional/ratelimiter_test.c
+++ b/bin/tests/optional/ratelimiter_test.c
@@ -104,8 +104,7 @@ main(int argc, char *argv[]) {
 	isc_interval_set(&linterval, 1, 0);
 
 	RUNTIME_CHECK(isc_mem_create(0, 0, &mctx) == ISC_R_SUCCESS);
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, 3, 0, &taskmgr) ==
-		      ISC_R_SUCCESS);
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, 3, &taskmgr) == ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_timermgr_create(mctx, &timermgr) ==
 		      ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_task_create(taskmgr, 0, &g_task) ==
diff --git a/bin/tests/optional/shutdown_test.c b/bin/tests/optional/shutdown_test.c
index 1eeaf07ea77..e2fe58e062e 100644
--- a/bin/tests/optional/shutdown_test.c
+++ b/bin/tests/optional/shutdown_test.c
@@ -183,7 +183,7 @@ main(int argc, char *argv[]) {
 	RUNTIME_CHECK(isc_mem_create(0, 0, &mctx) == ISC_R_SUCCESS);
 	mctx2 = NULL;
 	RUNTIME_CHECK(isc_mem_create(0, 0, &mctx2) == ISC_R_SUCCESS);
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, 0, &task_manager) ==
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, &task_manager) ==
 		      ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_timermgr_create(mctx, &timer_manager) ==
 		      ISC_R_SUCCESS);
diff --git a/bin/tests/optional/sig0_test.c b/bin/tests/optional/sig0_test.c
index 9db47c66b8c..7b6d8f72e72 100644
--- a/bin/tests/optional/sig0_test.c
+++ b/bin/tests/optional/sig0_test.c
@@ -228,8 +228,7 @@ main(int argc, char *argv[]) {
 	dst_result_register();
 
 	taskmgr = NULL;
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, 2, 0, &taskmgr) ==
-		      ISC_R_SUCCESS);
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, 2, &taskmgr) == ISC_R_SUCCESS);
 	task1 = NULL;
 	RUNTIME_CHECK(isc_task_create(taskmgr, 0, &task1) == ISC_R_SUCCESS);
 
diff --git a/bin/tests/optional/sock_test.c b/bin/tests/optional/sock_test.c
index f13a3ffe64c..54b813987ff 100644
--- a/bin/tests/optional/sock_test.c
+++ b/bin/tests/optional/sock_test.c
@@ -297,7 +297,7 @@ main(int argc, char *argv[]) {
 	 * The task manager is independent (other than memory context)
 	 */
 	manager = NULL;
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, 0, &manager) ==
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, &manager) ==
 		      ISC_R_SUCCESS);
 
 	/*
diff --git a/bin/tests/optional/task_test.c b/bin/tests/optional/task_test.c
index 10880103492..3f823302fd6 100644
--- a/bin/tests/optional/task_test.c
+++ b/bin/tests/optional/task_test.c
@@ -81,7 +81,7 @@ main(int argc, char *argv[]) {
 
 	RUNTIME_CHECK(isc_mem_create(0, 0, &mctx) == ISC_R_SUCCESS);
 
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, 0, &manager) ==
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, workers, &manager) ==
 		      ISC_R_SUCCESS);
 
 	RUNTIME_CHECK(isc_task_create(manager, 0, &t1) == ISC_R_SUCCESS);
diff --git a/bin/tests/optional/timer_test.c b/bin/tests/optional/timer_test.c
index 53d3b35ca22..580a7eb8488 100644
--- a/bin/tests/optional/timer_test.c
+++ b/bin/tests/optional/timer_test.c
@@ -110,7 +110,7 @@ main(int argc, char *argv[]) {
 	printf("%u workers\n", workers);
 
 	RUNTIME_CHECK(isc_mem_create(0, 0, &mctx1) == ISC_R_SUCCESS);
-	RUNTIME_CHECK(isc_taskmgr_create(mctx1, workers, 0, &manager) ==
+	RUNTIME_CHECK(isc_taskmgr_create(mctx1, workers, &manager) ==
 		      ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_timermgr_create(mctx1, &timgr) == ISC_R_SUCCESS);
 
diff --git a/bin/tests/optional/zone_test.c b/bin/tests/optional/zone_test.c
index b26acea0b17..3b8406d3ff0 100644
--- a/bin/tests/optional/zone_test.c
+++ b/bin/tests/optional/zone_test.c
@@ -284,7 +284,7 @@ main(int argc, char **argv) {
 
 	RUNTIME_CHECK(isc_app_start() == ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_mem_create(0, 0, &mctx) == ISC_R_SUCCESS);
-	RUNTIME_CHECK(isc_taskmgr_create(mctx, 2, 0, &taskmgr) ==
+	RUNTIME_CHECK(isc_taskmgr_create(mctx, 2, &taskmgr) ==
 		      ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_timermgr_create(mctx, &timermgr) == ISC_R_SUCCESS);
 	RUNTIME_CHECK(isc_socketmgr_create(mctx, &socketmgr) == ISC_R_SUCCESS);
diff --git a/bin/tests/system/pipelined/pipequeries.c b/bin/tests/system/pipelined/pipequeries.c
index 74de833fc16..9d8dddc2160 100644
--- a/bin/tests/system/pipelined/pipequeries.c
+++ b/bin/tests/system/pipelined/pipequeries.c
@@ -279,7 +279,7 @@ main(int argc, char *argv[]) {
 	RUNCHECK(dst_lib_init(mctx, NULL));
 
 	taskmgr = NULL;
-	RUNCHECK(isc_taskmgr_create(mctx, 1, 0, &taskmgr));
+	RUNCHECK(isc_taskmgr_create(mctx, 1, &taskmgr));
 	task = NULL;
 	RUNCHECK(isc_task_create(taskmgr, 0, &task));
 	timermgr = NULL;
diff --git a/bin/tests/system/tkey/keycreate.c b/bin/tests/system/tkey/keycreate.c
index c39f6a4ec18..935ee7bb6a9 100644
--- a/bin/tests/system/tkey/keycreate.c
+++ b/bin/tests/system/tkey/keycreate.c
@@ -239,7 +239,7 @@ main(int argc, char *argv[]) {
 	RUNCHECK(dst_lib_init(mctx, NULL));
 
 	taskmgr = NULL;
-	RUNCHECK(isc_taskmgr_create(mctx, 1, 0, &taskmgr));
+	RUNCHECK(isc_taskmgr_create(mctx, 1, &taskmgr));
 	task = NULL;
 	RUNCHECK(isc_task_create(taskmgr, 0, &task));
 	timermgr = NULL;
diff --git a/bin/tests/system/tkey/keydelete.c b/bin/tests/system/tkey/keydelete.c
index 547e8d03d3e..465076edafb 100644
--- a/bin/tests/system/tkey/keydelete.c
+++ b/bin/tests/system/tkey/keydelete.c
@@ -178,7 +178,7 @@ main(int argc, char **argv) {
 	RUNCHECK(dst_lib_init(mctx, NULL));
 
 	taskmgr = NULL;
-	RUNCHECK(isc_taskmgr_create(mctx, 1, 0, &taskmgr));
+	RUNCHECK(isc_taskmgr_create(mctx, 1, &taskmgr));
 	task = NULL;
 	RUNCHECK(isc_task_create(taskmgr, 0, &task));
 	timermgr = NULL;
diff --git a/bin/tools/mdig.c b/bin/tools/mdig.c
index 35942687fe3..39a3c16dd8b 100644
--- a/bin/tools/mdig.c
+++ b/bin/tools/mdig.c
@@ -1981,7 +1981,7 @@ main(int argc, char *argv[]) {
 		fatal("can't choose between IPv4 and IPv6");
 
 	taskmgr = NULL;
-	RUNCHECK(isc_taskmgr_create(mctx, 1, 0, &taskmgr));
+	RUNCHECK(isc_taskmgr_create(mctx, 1, &taskmgr));
 	task = NULL;
 	RUNCHECK(isc_task_create(taskmgr, 0, &task));
 	timermgr = NULL;
diff --git a/lib/dns/client.c b/lib/dns/client.c
index 9b7a212cf76..bb73a6b490b 100644
--- a/lib/dns/client.c
+++ b/lib/dns/client.c
@@ -379,7 +379,7 @@ dns_client_create(dns_client_t **clientp, unsigned int options) {
 	result = isc_app_ctxstart(actx);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
-	result = isc_taskmgr_createinctx(mctx, actx, 1, 0, &taskmgr);
+	result = isc_taskmgr_createinctx(mctx, actx, 1, &taskmgr);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
 	result = isc_socketmgr_createinctx(mctx, actx, &socketmgr);
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index b6fdd52051e..b1512545114 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -2468,7 +2468,7 @@ dns_dispatch_createtcp(dns_dispatchmgr_t *mgr, isc_socket_t *sock,
 
 	disp->ntasks = 1;
 	disp->task[0] = NULL;
-	result = isc_task_create(taskmgr, 50, &disp->task[0]);
+	result = isc_task_create(taskmgr, 0, &disp->task[0]);
 	if (result != ISC_R_SUCCESS)
 		goto kill_socket;
 
diff --git a/lib/dns/tests/dnstest.c b/lib/dns/tests/dnstest.c
index c2f927095d9..303ed77e2e4 100644
--- a/lib/dns/tests/dnstest.c
+++ b/lib/dns/tests/dnstest.c
@@ -109,7 +109,7 @@ create_managers(void) {
 	isc_result_t result;
 	ncpus = isc_os_ncpus();
 
-	CHECK(isc_taskmgr_create(mctx, ncpus, 0, &taskmgr));
+	CHECK(isc_taskmgr_create(mctx, ncpus, &taskmgr));
 	CHECK(isc_timermgr_create(mctx, &timermgr));
 	CHECK(isc_socketmgr_create(mctx, &socketmgr));
 	CHECK(isc_task_create(taskmgr, 0, &maintask));
diff --git a/lib/irs/context.c b/lib/irs/context.c
index 1e56786b09d..28873babb19 100644
--- a/lib/irs/context.c
+++ b/lib/irs/context.c
@@ -104,7 +104,7 @@ ctxs_init(isc_mem_t **mctxp, isc_appctx_t **actxp,
 	if (result != ISC_R_SUCCESS)
 		goto fail;
 
-	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, 0, taskmgrp);
+	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, taskmgrp);
 	if (result != ISC_R_SUCCESS)
 		goto fail;
 
diff --git a/lib/isc/include/isc/task.h b/lib/isc/include/isc/task.h
index b2d9c483846..239dfb664ee 100644
--- a/lib/isc/include/isc/task.h
+++ b/lib/isc/include/isc/task.h
@@ -631,11 +631,10 @@ isc_task_privilege(isc_task_t *task);
 
 isc_result_t
 isc_taskmgr_createinctx(isc_mem_t *mctx, isc_appctx_t *actx,
-			unsigned int workers, unsigned int default_quantum,
-			isc_taskmgr_t **managerp);
+			unsigned int workers, isc_taskmgr_t **managerp);
 isc_result_t
 isc_taskmgr_create(isc_mem_t *mctx, unsigned int workers,
-		   unsigned int default_quantum, isc_taskmgr_t **managerp);
+		   isc_taskmgr_t **managerp);
 /*%<
  * Create a new task manager.  isc_taskmgr_createinctx() also associates
  * the new manager with the specified application context.
@@ -648,10 +647,6 @@ isc_taskmgr_create(isc_mem_t *mctx, unsigned int workers,
  *	create 'workers' threads, but if at least one thread creation
  *	succeeds, isc_taskmgr_create() may return ISC_R_SUCCESS.
  *
- *\li	If 'default_quantum' is non-zero, then it will be used as the default
- *	quantum value when tasks are created.  If zero, then an implementation
- *	defined default quantum will be used.
- *
  * Requires:
  *
  *\li      'mctx' is a valid memory context.
diff --git a/lib/isc/task.c b/lib/isc/task.c
index a51d3359abf..fcd4cd9a489 100644
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@@ -134,6 +134,7 @@ struct isc__taskqueue {
 	isc_condition_t			work_available;
 	isc_thread_t			thread;
 	unsigned int			threadid;
+	unsigned int			tasks_waiting;
 	isc__taskmgr_t			*manager;
 };
 
@@ -151,7 +152,6 @@ struct isc__taskmgr {
 	isc__taskqueue_t		*queues;
 
 	/* Locked by task manager lock. */
-	unsigned int			default_quantum;
 	LIST(isc__task_t)		tasks;
 	isc_taskmgrmode_t		mode;
 	bool				pause_requested;
@@ -176,7 +176,17 @@ void
 isc__taskmgr_resume(isc_taskmgr_t *manager0);
 
 
-#define DEFAULT_DEFAULT_QUANTUM		25
+/*
+ * Unless specified otherwise when creating task we  normally run
+ * DEFAULT_QUANTUM events from a task in a single worker loop.
+ * If there are more than CONGESTED_TASK_LIMIT tasks waiting in the same queue
+ * we switch to CONGESTED_QUANTUM tasks per loop.
+ */
+
+#define DEFAULT_QUANTUM			25
+#define CONGESTED_QUANTUM		10
+#define CONGESTED_TASK_LIMIT		5
+
 #define FINISHED(m)			((m)->exiting && EMPTY((m)->tasks))
 
 /*%
@@ -292,7 +302,7 @@ isc_task_create_bound(isc_taskmgr_t *manager0, unsigned int quantum,
 	INIT_LIST(task->events);
 	INIT_LIST(task->on_shutdown);
 	task->nevents = 0;
-	task->quantum = (quantum > 0) ? quantum : manager->default_quantum;
+	task->quantum = quantum;
 	task->flags = 0;
 	task->now = 0;
 	isc_time_settoepoch(&task->tnow);
@@ -932,6 +942,7 @@ pop_readyq(isc__taskmgr_t *manager, int c) {
 
 	if (task != NULL) {
 		DEQUEUE(manager->queues[c].ready_tasks, task, ready_link);
+		manager->queues[c].tasks_waiting--;
 		if (ISC_LINK_LINKED(task, ready_priority_link)) {
 			DEQUEUE(manager->queues[c].ready_priority_tasks, task,
 				ready_priority_link);
@@ -950,6 +961,7 @@ pop_readyq(isc__taskmgr_t *manager, int c) {
 static inline void
 push_readyq(isc__taskmgr_t *manager, isc__task_t *task, int c) {
 	ENQUEUE(manager->queues[c].ready_tasks, task, ready_link);
+	manager->queues[c].tasks_waiting++;
 	if ((task->flags & TASK_F_PRIVILEGED) != 0) {
 		ENQUEUE(manager->queues[c].ready_priority_tasks, task,
 			ready_priority_link);
@@ -1095,6 +1107,16 @@ dispatch(isc__taskmgr_t *manager, unsigned int threadid) {
 		task = pop_readyq(manager, threadid);
 		if (task != NULL) {
 			unsigned int dispatch_count = 0;
+			unsigned int quantum = task->quantum;
+			if (quantum == 0) {
+				if (manager->queues[threadid].tasks_waiting
+				    < CONGESTED_TASK_LIMIT)
+				{
+					quantum = DEFAULT_QUANTUM;
+				} else {
+					quantum = CONGESTED_QUANTUM;
+				}
+			}
 			bool done = false;
 			bool requeue = false;
 			bool finished = false;
@@ -1201,7 +1223,7 @@ dispatch(isc__taskmgr_t *manager, unsigned int threadid) {
 					} else
 						task->state = task_state_idle;
 					done = true;
-				} else if (dispatch_count >= task->quantum) {
+				} else if (dispatch_count >= quantum) {
 					/*
 					 * Our quantum has expired, but
 					 * there is more work to be done.
@@ -1343,7 +1365,7 @@ manager_free(isc__taskmgr_t *manager) {
 
 isc_result_t
 isc_taskmgr_create(isc_mem_t *mctx, unsigned int workers,
-		    unsigned int default_quantum, isc_taskmgr_t **managerp)
+		   isc_taskmgr_t **managerp)
 {
 	unsigned int i;
 	isc__taskmgr_t *manager;
@@ -1369,10 +1391,6 @@ isc_taskmgr_create(isc_mem_t *mctx, unsigned int workers,
 
 	manager->workers = workers;
 
-	if (default_quantum == 0) {
-		default_quantum = DEFAULT_DEFAULT_QUANTUM;
-	}
-	manager->default_quantum = default_quantum;
 	INIT_LIST(manager->tasks);
 	manager->queues = isc_mem_get(mctx, workers * sizeof(isc__taskqueue_t));
 	RUNTIME_CHECK(manager->queues != NULL);
@@ -1400,6 +1418,7 @@ isc_taskmgr_create(isc_mem_t *mctx, unsigned int workers,
 
 		manager->queues[i].manager = manager;
 		manager->queues[i].threadid = i;
+		manager->queues[i].tasks_waiting = 0;
 		RUNTIME_CHECK(isc_thread_create(run, &manager->queues[i],
 						&manager->queues[i].thread)
 			      == ISC_R_SUCCESS);
@@ -1708,11 +1727,6 @@ isc_taskmgr_renderxml(isc_taskmgr_t *mgr0, xmlTextWriterPtr writer) {
 	TRY0(xmlTextWriterWriteFormatString(writer, "%d", mgr->workers));
 	TRY0(xmlTextWriterEndElement(writer)); /* worker-threads */
 
-	TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "default-quantum"));
-	TRY0(xmlTextWriterWriteFormatString(writer, "%d",
-					    mgr->default_quantum));
-	TRY0(xmlTextWriterEndElement(writer)); /* default-quantum */
-
 	TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "tasks-running"));
 	TRY0(xmlTextWriterWriteFormatString(writer, "%d",
 					    (int) mgr->tasks_running));
@@ -1809,10 +1823,6 @@ isc_taskmgr_renderjson(isc_taskmgr_t *mgr0, json_object *tasks) {
 	CHECKMEM(obj);
 	json_object_object_add(tasks, "worker-threads", obj);
 
-	obj = json_object_new_int(mgr->default_quantum);
-	CHECKMEM(obj);
-	json_object_object_add(tasks, "default-quantum", obj);
-
 	obj = json_object_new_int(mgr->tasks_running);
 	CHECKMEM(obj);
 	json_object_object_add(tasks, "tasks-running", obj);
@@ -1885,13 +1895,11 @@ isc_taskmgr_renderjson(isc_taskmgr_t *mgr0, json_object *tasks) {
 
 isc_result_t
 isc_taskmgr_createinctx(isc_mem_t *mctx, isc_appctx_t *actx,
-			unsigned int workers, unsigned int default_quantum,
-			isc_taskmgr_t **managerp)
+			unsigned int workers, isc_taskmgr_t **managerp)
 {
 	isc_result_t result;
 
-	result = isc_taskmgr_create(mctx, workers, default_quantum,
-				       managerp);
+	result = isc_taskmgr_create(mctx, workers, managerp);
 
 	if (result == ISC_R_SUCCESS)
 		isc_appctx_settaskmgr(actx, *managerp);
diff --git a/lib/isc/tests/isctest.c b/lib/isc/tests/isctest.c
index 66ca877e03e..79e27ccb1cc 100644
--- a/lib/isc/tests/isctest.c
+++ b/lib/isc/tests/isctest.c
@@ -86,7 +86,7 @@ create_managers(unsigned int workers) {
 		workers = atoi(p);
 	}
 
-	CHECK(isc_taskmgr_create(mctx, workers, 0, &taskmgr));
+	CHECK(isc_taskmgr_create(mctx, workers, &taskmgr));
 	CHECK(isc_task_create(taskmgr, 0, &maintask));
 	isc_taskmgr_setexcltask(taskmgr, maintask);
 
diff --git a/lib/isc/tests/task_test.c b/lib/isc/tests/task_test.c
index 18c1717b9a0..f23d6b85c90 100644
--- a/lib/isc/tests/task_test.c
+++ b/lib/isc/tests/task_test.c
@@ -712,7 +712,7 @@ manytasks(void **state) {
 	result = isc_mem_create(0, 0, &mctx);
 	assert_int_equal(result, ISC_R_SUCCESS);
 
-	result = isc_taskmgr_create(mctx, 4, 0, &taskmgr);
+	result = isc_taskmgr_create(mctx, 4, &taskmgr);
 	assert_int_equal(result, ISC_R_SUCCESS);
 
 	done = false;
diff --git a/lib/ns/tests/nstest.c b/lib/ns/tests/nstest.c
index 85c641bcd48..ac75a6991c4 100644
--- a/lib/ns/tests/nstest.c
+++ b/lib/ns/tests/nstest.c
@@ -182,7 +182,7 @@ create_managers(void) {
 	isc_event_t *event = NULL;
 	ncpus = isc_os_ncpus();
 
-	CHECK(isc_taskmgr_create(mctx, ncpus, 0, &taskmgr));
+	CHECK(isc_taskmgr_create(mctx, ncpus, &taskmgr));
 	CHECK(isc_task_create(taskmgr, 0, &maintask));
 	isc_taskmgr_setexcltask(taskmgr, maintask);
 	CHECK(isc_task_onshutdown(maintask, shutdown_managers, NULL));
diff --git a/lib/samples/nsprobe.c b/lib/samples/nsprobe.c
index 2fb49b1b616..3178fc12f4d 100644
--- a/lib/samples/nsprobe.c
+++ b/lib/samples/nsprobe.c
@@ -226,7 +226,7 @@ ctxs_init(isc_mem_t **mctxp, isc_appctx_t **actxp,
 	if (result != ISC_R_SUCCESS)
 		goto fail;
 
-	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, 0, taskmgrp);
+	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, taskmgrp);
 	if (result != ISC_R_SUCCESS)
 		goto fail;
 
diff --git a/lib/samples/resolve.c b/lib/samples/resolve.c
index 7965b3e261f..5424f4f9a6b 100644
--- a/lib/samples/resolve.c
+++ b/lib/samples/resolve.c
@@ -381,7 +381,7 @@ main(int argc, char *argv[]) {
 	result = isc_app_ctxstart(actx);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
-	result = isc_taskmgr_createinctx(mctx, actx, 1, 0, &taskmgr);
+	result = isc_taskmgr_createinctx(mctx, actx, 1, &taskmgr);
 	if (result != ISC_R_SUCCESS)
 		goto cleanup;
 	result = isc_socketmgr_createinctx(mctx, actx, &socketmgr);
diff --git a/lib/samples/sample-async.c b/lib/samples/sample-async.c
index f383fa2a8ea..bf6eb208f00 100644
--- a/lib/samples/sample-async.c
+++ b/lib/samples/sample-async.c
@@ -108,7 +108,7 @@ ctxs_init(isc_mem_t **mctxp, isc_appctx_t **actxp,
 	if (result != ISC_R_SUCCESS)
 		goto fail;
 
-	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, 0, taskmgrp);
+	result = isc_taskmgr_createinctx(*mctxp, *actxp, 1, taskmgrp);
 	if (result != ISC_R_SUCCESS)
 		goto fail;