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Date:      Fri, 19 Feb 2016 05:03:17 +0000 (UTC)
From:      Sepherosa Ziehau <sephe@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r295792 - head/sys/dev/hyperv/netvsc
Message-ID:  <201602190503.u1J53HY2050979@repo.freebsd.org>
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Author: sephe
Date: Fri Feb 19 05:03:17 2016
New Revision: 295792
URL: https://svnweb.freebsd.org/changeset/base/295792

Log:
  hyperv/hn: Add option to bind TX taskqueues to the specified CPU
  
  It will be used to help tracking host side transmission ring selection
  issue; and it will be turned on by default, once we have concrete result.
  
  Reviewed by:	adrian, Jun Su <junsu microsoft com>
  Approved by:	adrian (mento)
  MFC after:	1 week
  Sponsored by:	Microsoft OSTC
  Differential Revision:	https://reviews.freebsd.org/D5316

Modified:
  head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

Modified: head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
==============================================================================
--- head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c	Fri Feb 19 05:02:17 2016	(r295791)
+++ head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c	Fri Feb 19 05:03:17 2016	(r295792)
@@ -269,6 +269,10 @@ static int hn_use_txdesc_bufring = 1;
 SYSCTL_INT(_hw_hn, OID_AUTO, use_txdesc_bufring, CTLFLAG_RD,
     &hn_use_txdesc_bufring, 0, "Use buf_ring for TX descriptors");
 
+static int hn_bind_tx_taskq = -1;
+SYSCTL_INT(_hw_hn, OID_AUTO, bind_tx_taskq, CTLFLAG_RDTUN,
+    &hn_bind_tx_taskq, 0, "Bind TX taskqueue to the specified cpu");
+
 /*
  * Forward declarations
  */
@@ -383,8 +387,20 @@ netvsc_attach(device_t dev)
 	if (hn_tx_taskq == NULL) {
 		sc->hn_tx_taskq = taskqueue_create("hn_tx", M_WAITOK,
 		    taskqueue_thread_enqueue, &sc->hn_tx_taskq);
-		taskqueue_start_threads(&sc->hn_tx_taskq, 1, PI_NET, "%s tx",
-		    device_get_nameunit(dev));
+		if (hn_bind_tx_taskq >= 0) {
+			int cpu = hn_bind_tx_taskq;
+			cpuset_t cpu_set;
+
+			if (cpu > mp_ncpus - 1)
+				cpu = mp_ncpus - 1;
+			CPU_SETOF(cpu, &cpu_set);
+			taskqueue_start_threads_cpuset(&sc->hn_tx_taskq, 1,
+			    PI_NET, &cpu_set, "%s tx",
+			    device_get_nameunit(dev));
+		} else {
+			taskqueue_start_threads(&sc->hn_tx_taskq, 1, PI_NET,
+			    "%s tx", device_get_nameunit(dev));
+		}
 	} else {
 		sc->hn_tx_taskq = hn_tx_taskq;
 	}
@@ -2409,7 +2425,18 @@ hn_tx_taskq_create(void *arg __unused)
 
 	hn_tx_taskq = taskqueue_create("hn_tx", M_WAITOK,
 	    taskqueue_thread_enqueue, &hn_tx_taskq);
-	taskqueue_start_threads(&hn_tx_taskq, 1, PI_NET, "hn tx");
+	if (hn_bind_tx_taskq >= 0) {
+		int cpu = hn_bind_tx_taskq;
+		cpuset_t cpu_set;
+
+		if (cpu > mp_ncpus - 1)
+			cpu = mp_ncpus - 1;
+		CPU_SETOF(cpu, &cpu_set);
+		taskqueue_start_threads_cpuset(&hn_tx_taskq, 1, PI_NET,
+		    &cpu_set, "hn tx");
+	} else {
+		taskqueue_start_threads(&hn_tx_taskq, 1, PI_NET, "hn tx");
+	}
 }
 SYSINIT(hn_txtq_create, SI_SUB_DRIVERS, SI_ORDER_FIRST,
     hn_tx_taskq_create, NULL);

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