Create system taskq ("systqmp") which runs without the kernel lock;

currently unused.

ok dlg@
manpage improvement and ok jmc@

3 files changed, 26 insertions, 9 deletions

diff --git a/share/man/man9/task_add.9 b/share/man/man9/task_add.9
index a7a8ec9a36a..a5b516d2ff7 100644
--- a/share/man/man9/task_add.9
+++ b/share/man/man9/task_add.9
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: task_add.9,v 1.11 2014/04/02 13:19:01 mpi Exp $
+.\"	$OpenBSD: task_add.9,v 1.12 2014/06/11 08:47:53 blambert Exp $
 .\"
 .\" Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: April 2 2014 $
+.Dd $Mdocdate: June 11 2014 $
 .Dt TASK_ADD 9
 .Os
 .Sh NAME
@@ -38,6 +38,7 @@
 .Ft int
 .Fn "task_del" "struct taskq *tq" "struct task *t"
 .Vt extern struct taskq *const systq;
+.Vt extern struct taskq *const systqmp;
 .Fn "TASK_INITIALIZER" "void (*fn)(void *, void *)" "void *arg1" "void *arg2"
 .Sh DESCRIPTION
 The
@@ -125,12 +126,15 @@ against a different taskq than the one given in a previous call to
 .Fn task_add
 is an error and will lead to undefined behaviour.
 .Pp
-The kernel provides a system taskq
-.Va systq
-that can be used by any subsystem for short lived tasks.
-It is serviced by a single thread and can therefore provide predictable
+The kernel provides two system taskqs:
+.Va systq ,
+which executes while holding the kernel lock, and
+.Va systqmp ,
+which does not hold the kernel lock during execution.
+They can both be used by any subsystem for short lived tasks.
+They are serviced by a single thread and can therefore provide predictable
 ordering of work.
-Work can be scheduled on the system taskq from callers at or below IPL_HIGH.
+Work can be scheduled on the system taskqs from callers at or below IPL_HIGH.
 .Pp
 A task declaration can be initialised with the
 .Fn TASK_INITIALIZER
diff --git a/sys/kern/kern_task.c b/sys/kern/kern_task.c
index 2ba2d990ec0..04592ad7f4e 100644
--- a/sys/kern/kern_task.c
+++ b/sys/kern/kern_task.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_task.c,v 1.8 2013/12/11 22:39:49 kettenis Exp $ */
+/*	$OpenBSD: kern_task.c,v 1.9 2014/06/11 08:47:53 blambert Exp $ */
 
 /*
  * Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
@@ -50,7 +50,18 @@ struct taskq taskq_sys = {
 	TAILQ_HEAD_INITIALIZER(taskq_sys.tq_worklist)
 };
 
+struct taskq taskq_sys_mp = {
+	TQ_S_CREATED,
+	0,
+	1,
+	1,
+	"systqmp",
+	MUTEX_INITIALIZER(IPL_HIGH),
+	TAILQ_HEAD_INITIALIZER(taskq_sys_mp.tq_worklist)
+};
+
 struct taskq *const systq = &taskq_sys;
+struct taskq *const systqmp = &taskq_sys_mp;
 
 void	taskq_init(void); /* called in init_main.c */
 void	taskq_create_thread(void *);
@@ -61,6 +72,7 @@ void
 taskq_init(void)
 {
 	kthread_create_deferred(taskq_create_thread, systq);
+	kthread_create_deferred(taskq_create_thread, systqmp);
 }
 
 struct taskq *
diff --git a/sys/sys/task.h b/sys/sys/task.h
index 1691aef3650..fc19aa5f83d 100644
--- a/sys/sys/task.h
+++ b/sys/sys/task.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: task.h,v 1.5 2013/12/23 04:20:47 dlg Exp $ */
+/*	$OpenBSD: task.h,v 1.6 2014/06/11 08:47:53 blambert Exp $ */
 
 /*
  * Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
@@ -33,6 +33,7 @@ struct task {
 
 #ifdef _KERNEL
 extern struct taskq *const systq;
+extern struct taskq *const systqmp;
 
 struct taskq	*taskq_create(const char *, unsigned int, int);
 void		 taskq_destroy(struct taskq *);