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Date:      Fri, 13 Oct 2017 02:01:04 +0000 (UTC)
From:      Sepherosa Ziehau <sephe@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org
Subject:   svn commit: r324572 - stable/10/sys/dev/hyperv/vmbus
Message-ID:  <201710130201.v9D2141B017093@repo.freebsd.org>
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Author: sephe
Date: Fri Oct 13 02:01:03 2017
New Revision: 324572
URL: https://svnweb.freebsd.org/changeset/base/324572

Log:
  MFC 324487
  
      hyperv/vmbus: Add tunable to pin/unpin event tasks.
  
      Event tasks are pinned to their respective CPU by default, in the same
      fashion as they were.
  
      Unpin the event tasks by setting hw.vmbus.pin_evttask to 0, if certain
      CPUs serve special purpose.
  
      Sponsored by:   Microsoft

Modified:
  stable/10/sys/dev/hyperv/vmbus/vmbus.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/dev/hyperv/vmbus/vmbus.c
==============================================================================
--- stable/10/sys/dev/hyperv/vmbus/vmbus.c	Thu Oct 12 21:58:51 2017	(r324571)
+++ stable/10/sys/dev/hyperv/vmbus/vmbus.c	Fri Oct 13 02:01:03 2017	(r324572)
@@ -129,6 +129,13 @@ static struct vmbus_softc	*vmbus_sc;
 
 extern inthand_t IDTVEC(rsvd), IDTVEC(vmbus_isr);
 
+SYSCTL_NODE(_hw, OID_AUTO, vmbus, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
+    "Hyper-V vmbus");
+
+static int			vmbus_pin_evttask = 1;
+SYSCTL_INT(_hw_vmbus, OID_AUTO, pin_evttask, CTLFLAG_RDTUN,
+    &vmbus_pin_evttask, 0, "Pin event tasks to their respective CPU");
+
 static const uint32_t		vmbus_version[] = {
 	VMBUS_VERSION_WIN8_1,
 	VMBUS_VERSION_WIN8,
@@ -978,13 +985,15 @@ vmbus_intr_setup(struct vmbus_softc *sc)
 		taskqueue_start_threads(VMBUS_PCPU_PTR(sc, event_tq, cpu),
 		    1, PI_NET, "hvevent%d", cpu);
 
-		CPU_SETOF(cpu, &cpu_mask);
-		TASK_INIT(&cpuset_task, 0, vmbus_cpuset_setthread_task,
-		    &cpu_mask);
-		taskqueue_enqueue(VMBUS_PCPU_GET(sc, event_tq, cpu),
-		    &cpuset_task);
-		taskqueue_drain(VMBUS_PCPU_GET(sc, event_tq, cpu),
-		    &cpuset_task);
+		if (vmbus_pin_evttask) {
+			CPU_SETOF(cpu, &cpu_mask);
+			TASK_INIT(&cpuset_task, 0, vmbus_cpuset_setthread_task,
+			    &cpu_mask);
+			taskqueue_enqueue(VMBUS_PCPU_GET(sc, event_tq, cpu),
+			    &cpuset_task);
+			taskqueue_drain(VMBUS_PCPU_GET(sc, event_tq, cpu),
+			    &cpuset_task);
+		}
 
 		/*
 		 * Setup tasks and taskqueues to handle messages.

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