Make the multiple DPC threads an option, and create only one by default.

This avoids the need for sched_bind() in the default case so that you
can start up the NDIS subsystem at boot time when only CPU 0 is running.

There are potentially ways to fix it so that the DPC threads aren't
started until after the other CPUs are launched, but doing it correctly
is tricky. You need to defer the startup of the ntoskrnl subsystem
(ntoskrnl_libinit()), not just defer ndis_attach().

For now, I don't think it will make much difference having just the
single DPC thread (I started out with just one anyway). Note that this
turns the KeSetTargetProcessorDpc() routine into a no-op, since the
CPU number in struct kdpc is now ignored.

1 files changed, 31 insertions, 2 deletions

diff --git a/sys/compat/ndis/subr_ntoskrnl.c b/sys/compat/ndis/subr_ntoskrnl.c
index b2a231b..bcd8e45 100644
--- a/sys/compat/ndis/subr_ntoskrnl.c
+++ b/sys/compat/ndis/subr_ntoskrnl.c
@@ -269,7 +269,11 @@ ntoskrnl_libinit()
 	mtx_init(&ntoskrnl_calllock, MTX_NTOSKRNL_SPIN_LOCK, NULL, MTX_SPIN);
 
 	kq_queues = ExAllocatePoolWithTag(NonPagedPool,
+#ifdef NTOSKRNL_MULTIPLE_DPCS
 	    sizeof(kdpc_queue) * mp_ncpus, 0);
+#else
+	    sizeof(kdpc_queue), 0);
+#endif
 
 	if (kq_queues == NULL)
 		return(ENOMEM);
@@ -287,7 +291,11 @@ ntoskrnl_libinit()
 	 * Launch the DPC threads.
 	 */
 
+#ifdef NTOSKRNL_MULTIPLE_DPCS
         for (i = 0; i < mp_ncpus; i++) {
+#else
+        for (i = 0; i < 1; i++) {
+#endif
 		kq = kq_queues + i;
 		kq->kq_cpu = i;
 		sprintf(name, "Windows DPC %d", i);
@@ -3558,9 +3566,11 @@ ntoskrnl_dpc_thread(arg)
 	 */
 
 	mtx_lock_spin(&sched_lock);
+#ifdef NTOSKRNL_MULTIPLE_DPCS
 #if __FreeBSD_version >= 502102
 	sched_bind(curthread, kq->kq_cpu);
 #endif
+#endif
         sched_prio(curthread, PRI_MIN_KERN);
 #if __FreeBSD_version < 600000
         curthread->td_base_pri = PRI_MIN_KERN;
@@ -3611,7 +3621,11 @@ ntoskrnl_destroy_dpc_threads(void)
 	int			i;
 
 	kq = kq_queues;
+#ifdef NTOSKRNL_MULTIPLE_DPCS
 	for (i = 0; i < mp_ncpus; i++) {
+#else
+	for (i = 0; i < 1; i++) {
+#endif
 		kq += i;
 
 		kq->kq_exit = 1;
@@ -3680,6 +3694,9 @@ KeInsertQueueDpc(dpc, sysarg1, sysarg2)
 	if (dpc == NULL)
 		return(FALSE);
 
+	kq = kq_queues;
+
+#ifdef NTOSKRNL_MULTIPLE_DPCS
 	KeRaiseIrql(DISPATCH_LEVEL, &irql);
 
 	/*
@@ -3687,13 +3704,15 @@ KeInsertQueueDpc(dpc, sysarg1, sysarg2)
 	 * that scheduled it.
 	 */
 
-	kq = kq_queues;
 	if (dpc->k_num == KDPC_CPU_DEFAULT)
 		kq += curthread->td_oncpu;
 	else
 		kq += dpc->k_num;
-
 	KeAcquireSpinLockAtDpcLevel(&kq->kq_lock);
+#else
+	KeAcquireSpinLock(&kq->kq_lock, &irql);
+#endif
+
 	r = ntoskrnl_insert_dpc(&kq->kq_disp, dpc);
 	if (r == TRUE) {
 		dpc->k_sysarg1 = sysarg1;
@@ -3719,11 +3738,17 @@ KeRemoveQueueDpc(dpc)
 	if (dpc == NULL)
 		return(FALSE);
 
+#ifdef NTOSKRNL_MULTIPLE_DPCS
 	KeRaiseIrql(DISPATCH_LEVEL, &irql);
 
 	kq = kq_queues + dpc->k_num;
 
 	KeAcquireSpinLockAtDpcLevel(&kq->kq_lock);
+#else
+	kq = kq_queues;
+	KeAcquireSpinLock(&kq->kq_lock, &irql);
+#endif
+
 	if (dpc->k_dpclistentry.nle_flink == &dpc->k_dpclistentry) {
 		KeReleaseSpinLockFromDpcLevel(&kq->kq_lock);
 		KeLowerIrql(irql);
@@ -3775,7 +3800,11 @@ KeFlushQueuedDpcs(void)
 	 * for them to drain.
 	 */
 
+#ifdef NTOSKRNL_MULTIPLE_DPCS
 	for (i = 0; i < mp_ncpus; i++) {
+#else
+	for (i = 0; i < 1; i++) {
+#endif
 		kq = kq_queues + i;
 		KeSetEvent(&kq->kq_proc, IO_NO_INCREMENT, FALSE);
 		KeWaitForSingleObject(&kq->kq_done, 0, 0, TRUE, NULL);