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Date:      Thu, 13 Nov 2014 00:40:35 +0000 (UTC)
From:      Luigi Rizzo <luigi@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r274459 - head/sys/dev/netmap
Message-ID:  <201411130040.sAD0eZ3g099007@svn.freebsd.org>
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Author: luigi
Date: Thu Nov 13 00:40:34 2014
New Revision: 274459
URL: https://svnweb.freebsd.org/changeset/base/274459

Log:
  add support for private knote lock (reduces lock contention),
  adapting OS_selrecord accordingly.
  Problem and fix suggested by adrian and jmg

Modified:
  head/sys/dev/netmap/netmap.c
  head/sys/dev/netmap/netmap_freebsd.c
  head/sys/dev/netmap/netmap_kern.h

Modified: head/sys/dev/netmap/netmap.c
==============================================================================
--- head/sys/dev/netmap/netmap.c	Thu Nov 13 00:30:17 2014	(r274458)
+++ head/sys/dev/netmap/netmap.c	Thu Nov 13 00:40:34 2014	(r274459)
@@ -375,9 +375,14 @@ ports attached to the switch)
 
 /* reduce conditional code */
 // linux API, use for the knlist in FreeBSD
-#define init_waitqueue_head(x)	knlist_init_mtx(&(x)->si_note, NULL)
+/* use a private mutex for the knlist */
+#define init_waitqueue_head(x) do {			\
+	struct mtx *m = &(x)->m;			\
+	mtx_init(m, "nm_kn_lock", NULL, MTX_DEF);	\
+	knlist_init_mtx(&(x)->si.si_note, m);		\
+    } while (0)
 
-void freebsd_selwakeup(struct selinfo *si, int pri);
+#define OS_selrecord(a, b)	selrecord(a, &((b)->si))
 #define OS_selwakeup(a, b)	freebsd_selwakeup(a, b)
 
 #elif defined(linux)
@@ -806,6 +811,19 @@ netmap_krings_create(struct netmap_adapt
 }
 
 
+#ifdef __FreeBSD__
+static void
+netmap_knlist_destroy(NM_SELINFO_T *si)
+{
+	/* XXX kqueue(9) needed; these will mirror knlist_init. */
+	knlist_delete(&si->si.si_note, curthread, 0 /* not locked */ );
+	knlist_destroy(&si->si.si_note);
+	/* now we don't need the mutex anymore */
+	mtx_destroy(&si->m);
+}
+#endif /* __FreeBSD__ */
+
+
 /* undo the actions performed by netmap_krings_create */
 /* call with NMG_LOCK held */
 void
@@ -816,6 +834,7 @@ netmap_krings_delete(struct netmap_adapt
 	/* we rely on the krings layout described above */
 	for ( ; kring != na->tailroom; kring++) {
 		mtx_destroy(&kring->q_lock);
+		netmap_knlist_destroy(&kring->si);
 	}
 	free(na->tx_rings, M_DEVBUF);
 	na->tx_rings = na->rx_rings = na->tailroom = NULL;
@@ -996,9 +1015,8 @@ netmap_do_unregif(struct netmap_priv_d *
 		 * XXX The wake up now must happen during *_down(), when
 		 * we order all activities to stop. -gl
 		 */
-		/* XXX kqueue(9) needed; these will mirror knlist_init. */
-		/* knlist_destroy(&na->tx_si.si_note); */
-		/* knlist_destroy(&na->rx_si.si_note); */
+		netmap_knlist_destroy(&na->tx_si);
+		netmap_knlist_destroy(&na->rx_si);
 
 		/* delete rings and buffers */
 		netmap_mem_rings_delete(na);
@@ -1310,7 +1328,7 @@ netmap_rxsync_from_host(struct netmap_ad
 
 	/* access copies of cur,tail in the kring */
 	if (kring->rcur == kring->rtail && td) /* no bufs available */
-		selrecord(td, &kring->si);
+		OS_selrecord(td, &kring->si);
 
 	mbq_unlock(q);
 	return ret;
@@ -2410,7 +2428,7 @@ flush_tx:
 			}
 		}
 		if (want_tx && retry_tx && !is_kevent) {
-			selrecord(td, check_all_tx ?
+			OS_selrecord(td, check_all_tx ?
 			    &na->tx_si : &na->tx_rings[priv->np_txqfirst].si);
 			retry_tx = 0;
 			goto flush_tx;
@@ -2479,7 +2497,7 @@ do_retry_rx:
 		}
 
 		if (retry_rx && !is_kevent)
-			selrecord(td, check_all_rx ?
+			OS_selrecord(td, check_all_rx ?
 			    &na->rx_si : &na->rx_rings[priv->np_rxqfirst].si);
 		if (send_down > 0 || retry_rx) {
 			retry_rx = 0;
@@ -3054,8 +3072,15 @@ netmap_init(void)
 	if (error != 0)
 		goto fail;
 	/* XXX could use make_dev_credv() to get error number */
+#ifdef __FreeBSD__
+	/* support for the 'eternal' flag */
+	netmap_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD,
+		&netmap_cdevsw, 0, NULL, UID_ROOT, GID_WHEEL, 0660,
+			      "netmap");
+#else
 	netmap_dev = make_dev(&netmap_cdevsw, 0, UID_ROOT, GID_WHEEL, 0660,
 			      "netmap");
+#endif
 	if (!netmap_dev)
 		goto fail;
 

Modified: head/sys/dev/netmap/netmap_freebsd.c
==============================================================================
--- head/sys/dev/netmap/netmap_freebsd.c	Thu Nov 13 00:30:17 2014	(r274458)
+++ head/sys/dev/netmap/netmap_freebsd.c	Thu Nov 13 00:40:34 2014	(r274459)
@@ -656,25 +656,24 @@ netmap_open(struct cdev *dev, int oflags
  * and do not need the selrecord().
  */
 
-void freebsd_selwakeup(struct selinfo *si, int pri);
 
 void
-freebsd_selwakeup(struct selinfo *si, int pri)
+freebsd_selwakeup(struct nm_selinfo *si, int pri)
 {
 	if (netmap_verbose)
-		D("on knote %p", &si->si_note);
-	selwakeuppri(si, pri);
+		D("on knote %p", &si->si.si_note);
+	selwakeuppri(&si->si, pri);
 	/* use a non-zero hint to tell the notification from the
 	 * call done in kqueue_scan() which uses 0
 	 */
-	KNOTE_UNLOCKED(&si->si_note, 0x100 /* notification */);
+	KNOTE_UNLOCKED(&si->si.si_note, 0x100 /* notification */);
 }
 
 static void
 netmap_knrdetach(struct knote *kn)
 {
 	struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
-	struct selinfo *si = priv->np_rxsi;
+	struct selinfo *si = &priv->np_rxsi->si;
 
 	D("remove selinfo %p", si);
 	knlist_remove(&si->si_note, kn, 0);
@@ -684,7 +683,7 @@ static void
 netmap_knwdetach(struct knote *kn)
 {
 	struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
-	struct selinfo *si = priv->np_txsi;
+	struct selinfo *si = &priv->np_txsi->si;
 
 	D("remove selinfo %p", si);
 	knlist_remove(&si->si_note, kn, 0);
@@ -756,7 +755,7 @@ netmap_kqfilter(struct cdev *dev, struct
 	struct netmap_priv_d *priv;
 	int error;
 	struct netmap_adapter *na;
-	struct selinfo *si;
+	struct nm_selinfo *si;
 	int ev = kn->kn_filter;
 
 	if (ev != EVFILT_READ && ev != EVFILT_WRITE) {
@@ -779,7 +778,7 @@ netmap_kqfilter(struct cdev *dev, struct
 	kn->kn_fop = (ev == EVFILT_WRITE) ?
 		&netmap_wfiltops : &netmap_rfiltops;
 	kn->kn_hook = priv;
-	knlist_add(&si->si_note, kn, 1);
+	knlist_add(&si->si.si_note, kn, 1);
 	// XXX unlock(priv)
 	ND("register %p %s td %p priv %p kn %p np_nifp %p kn_fp/fpop %s",
 		na, na->ifp->if_xname, curthread, priv, kn,

Modified: head/sys/dev/netmap/netmap_kern.h
==============================================================================
--- head/sys/dev/netmap/netmap_kern.h	Thu Nov 13 00:30:17 2014	(r274458)
+++ head/sys/dev/netmap/netmap_kern.h	Thu Nov 13 00:40:34 2014	(r274459)
@@ -55,7 +55,7 @@
 #define NMG_UNLOCK()	sx_xunlock(&netmap_global_lock)
 #define NMG_LOCK_ASSERT()	sx_assert(&netmap_global_lock, SA_XLOCKED)
 
-#define	NM_SELINFO_T	struct selinfo
+#define	NM_SELINFO_T	struct nm_selinfo
 #define	MBUF_LEN(m)	((m)->m_pkthdr.len)
 #define	MBUF_IFP(m)	((m)->m_pkthdr.rcvif)
 #define	NM_SEND_UP(ifp, m)	((NA(ifp))->if_input)(ifp, m)
@@ -88,6 +88,13 @@ struct netmap_adapter *netmap_getna(if_t
 
 MALLOC_DECLARE(M_NETMAP);
 
+struct nm_selinfo {
+	struct selinfo si;
+	struct mtx m;
+};
+
+void freebsd_selwakeup(struct nm_selinfo *si, int pri);
+
 // XXX linux struct, not used in FreeBSD
 struct net_device_ops {
 };

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