Author: adrian
Date: Thu Aug 29 19:35:14 2013
New Revision: 255038
URL: http://svnweb.freebsd.org/changeset/base/255038
Log:
Convert the if_lagg rwlock to an rmlock.
We've been seeing lots of cache line contention (but not lock contention!)
in our workloads between the various TX and RX threads going on.
The write lock is only grabbed when configuration changes are made - which
are infrequent.
With this patch, the contention and cycles spent waiting for updates
disappear.
Sponsored by: Netflix, Inc.
Modified:
head/sys/net/if_lagg.c
head/sys/net/if_lagg.h
Modified: head/sys/net/if_lagg.c
==============================================================================
--- head/sys/net/if_lagg.c Thu Aug 29 18:36:47 2013 (r255037)
+++ head/sys/net/if_lagg.c Thu Aug 29 19:35:14 2013 (r255038)
@@ -37,7 +37,7 @@ __FBSDID("$FreeBSD$");
#include <sys/proc.h>
#include <sys/hash.h>
#include <sys/lock.h>
-#include <sys/rwlock.h>
+#include <sys/rmlock.h>
#include <sys/taskqueue.h>
#include <sys/eventhandler.h>
@@ -233,16 +233,17 @@ lagg_register_vlan(void *arg, struct ifn
{
struct lagg_softc *sc = ifp->if_softc;
struct lagg_port *lp;
+ struct rm_priotracker tracker;
if (ifp->if_softc != arg) /* Not our event */
return;
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
if (!SLIST_EMPTY(&sc->sc_ports)) {
SLIST_FOREACH(lp, &sc->sc_ports, lp_entries)
EVENTHANDLER_INVOKE(vlan_config, lp->lp_ifp, vtag);
}
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
}
/*
@@ -254,16 +255,17 @@ lagg_unregister_vlan(void *arg, struct i
{
struct lagg_softc *sc = ifp->if_softc;
struct lagg_port *lp;
+ struct rm_priotracker tracker;
if (ifp->if_softc != arg) /* Not our event */
return;
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
if (!SLIST_EMPTY(&sc->sc_ports)) {
SLIST_FOREACH(lp, &sc->sc_ports, lp_entries)
EVENTHANDLER_INVOKE(vlan_unconfig, lp->lp_ifp, vtag);
}
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
}
static int
@@ -322,9 +324,15 @@ lagg_clone_create(struct if_clone *ifc,
}
}
LAGG_LOCK_INIT(sc);
+ LAGG_CALLOUT_LOCK_INIT(sc);
SLIST_INIT(&sc->sc_ports);
TASK_INIT(&sc->sc_lladdr_task, 0, lagg_port_setlladdr, sc);
- callout_init_rw(&sc->sc_callout, &sc->sc_mtx, CALLOUT_SHAREDLOCK);
+
+ /*
+ * This uses the callout lock rather than the rmlock; one can't
+ * hold said rmlock during SWI.
+ */
+ callout_init_mtx(&sc->sc_callout, &sc->sc_call_mtx, 0);
/* Initialise pseudo media types */
ifmedia_init(&sc->sc_media, 0, lagg_media_change,
@@ -389,7 +397,10 @@ lagg_clone_destroy(struct ifnet *ifp)
ether_ifdetach(ifp);
if_free(ifp);
+ /* This grabs sc_callout_mtx, serialising it correctly */
callout_drain(&sc->sc_callout);
+
+ /* At this point it's drained; we can free this */
counter_u64_free(sc->sc_ipackets);
counter_u64_free(sc->sc_opackets);
counter_u64_free(sc->sc_ibytes);
@@ -401,6 +412,7 @@ lagg_clone_destroy(struct ifnet *ifp)
taskqueue_drain(taskqueue_swi, &sc->sc_lladdr_task);
LAGG_LOCK_DESTROY(sc);
+ LAGG_CALLOUT_LOCK_DESTROY(sc);
free(sc, M_DEVBUF);
}
@@ -764,6 +776,7 @@ lagg_port_ioctl(struct ifnet *ifp, u_lon
struct lagg_softc *sc;
struct lagg_port *lp = NULL;
int error = 0;
+ struct rm_priotracker tracker;
/* Should be checked by the caller */
if (ifp->if_type != IFT_IEEE8023ADLAG ||
@@ -778,15 +791,15 @@ lagg_port_ioctl(struct ifnet *ifp, u_lon
break;
}
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
if ((lp = ifp->if_lagg) == NULL || lp->lp_softc != sc) {
error = ENOENT;
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
break;
}
lagg_port2req(lp, rp);
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
break;
case SIOCSIFCAP:
@@ -955,21 +968,22 @@ lagg_ioctl(struct ifnet *ifp, u_long cmd
struct thread *td = curthread;
char *buf, *outbuf;
int count, buflen, len, error = 0;
+ struct rm_priotracker tracker;
bzero(&rpbuf, sizeof(rpbuf));
switch (cmd) {
case SIOCGLAGG:
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
count = 0;
SLIST_FOREACH(lp, &sc->sc_ports, lp_entries)
count++;
buflen = count * sizeof(struct lagg_reqport);
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
outbuf = malloc(buflen, M_TEMP, M_WAITOK | M_ZERO);
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
ra->ra_proto = sc->sc_proto;
if (sc->sc_req != NULL)
(*sc->sc_req)(sc, (caddr_t)&ra->ra_psc);
@@ -987,7 +1001,7 @@ lagg_ioctl(struct ifnet *ifp, u_long cmd
buf += sizeof(rpbuf);
len -= sizeof(rpbuf);
}
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
ra->ra_ports = count;
ra->ra_size = count * sizeof(rpbuf);
error = copyout(outbuf, ra->ra_port, ra->ra_size);
@@ -1065,16 +1079,16 @@ lagg_ioctl(struct ifnet *ifp, u_long cmd
break;
}
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
if ((lp = (struct lagg_port *)tpif->if_lagg) == NULL ||
lp->lp_softc != sc) {
error = ENOENT;
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
break;
}
lagg_port2req(lp, rp);
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
break;
case SIOCSLAGGPORT:
error = priv_check(td, PRIV_NET_LAGG);
@@ -1280,14 +1294,15 @@ lagg_transmit(struct ifnet *ifp, struct
{
struct lagg_softc *sc = (struct lagg_softc *)ifp->if_softc;
int error, len, mcast;
+ struct rm_priotracker tracker;
len = m->m_pkthdr.len;
mcast = (m->m_flags & (M_MCAST | M_BCAST)) ? 1 : 0;
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
/* We need a Tx algorithm and at least one port */
if (sc->sc_proto == LAGG_PROTO_NONE || sc->sc_count == 0) {
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
m_freem(m);
ifp->if_oerrors++;
return (ENXIO);
@@ -1296,7 +1311,7 @@ lagg_transmit(struct ifnet *ifp, struct
ETHER_BPF_MTAP(ifp, m);
error = (*sc->sc_start)(sc, m);
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
if (error == 0) {
counter_u64_add(sc->sc_opackets, 1);
@@ -1322,12 +1337,13 @@ lagg_input(struct ifnet *ifp, struct mbu
struct lagg_port *lp = ifp->if_lagg;
struct lagg_softc *sc = lp->lp_softc;
struct ifnet *scifp = sc->sc_ifp;
+ struct rm_priotracker tracker;
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
if ((scifp->if_drv_flags & IFF_DRV_RUNNING) == 0 ||
(lp->lp_flags & LAGG_PORT_DISABLED) ||
sc->sc_proto == LAGG_PROTO_NONE) {
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
m_freem(m);
return (NULL);
}
@@ -1346,7 +1362,7 @@ lagg_input(struct ifnet *ifp, struct mbu
}
}
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
return (m);
}
@@ -1367,16 +1383,17 @@ lagg_media_status(struct ifnet *ifp, str
{
struct lagg_softc *sc = (struct lagg_softc *)ifp->if_softc;
struct lagg_port *lp;
+ struct rm_priotracker tracker;
imr->ifm_status = IFM_AVALID;
imr->ifm_active = IFM_ETHER | IFM_AUTO;
- LAGG_RLOCK(sc);
+ LAGG_RLOCK(sc, &tracker);
SLIST_FOREACH(lp, &sc->sc_ports, lp_entries) {
if (LAGG_PORTACTIVE(lp))
imr->ifm_status |= IFM_ACTIVE;
}
- LAGG_RUNLOCK(sc);
+ LAGG_RUNLOCK(sc, &tracker);
}
static void
Modified: head/sys/net/if_lagg.h
==============================================================================
--- head/sys/net/if_lagg.h Thu Aug 29 18:36:47 2013 (r255037)
+++ head/sys/net/if_lagg.h Thu Aug 29 19:35:14 2013 (r255038)
@@ -187,7 +187,8 @@ struct lagg_llq {
struct lagg_softc {
struct ifnet *sc_ifp; /* virtual interface */
- struct rwlock sc_mtx;
+ struct rmlock sc_mtx;
+ struct mtx sc_call_mtx;
int sc_proto; /* lagg protocol */
u_int sc_count; /* number of ports */
u_int sc_active; /* active port count */
@@ -255,14 +256,19 @@ struct lagg_port {
SLIST_ENTRY(lagg_port) lp_entries;
};
-#define LAGG_LOCK_INIT(_sc) rw_init(&(_sc)->sc_mtx, "if_lagg
rwlock")
-#define LAGG_LOCK_DESTROY(_sc) rw_destroy(&(_sc)->sc_mtx)
-#define LAGG_RLOCK(_sc) rw_rlock(&(_sc)->sc_mtx)
-#define LAGG_WLOCK(_sc) rw_wlock(&(_sc)->sc_mtx)
-#define LAGG_RUNLOCK(_sc) rw_runlock(&(_sc)->sc_mtx)
-#define LAGG_WUNLOCK(_sc) rw_wunlock(&(_sc)->sc_mtx)
-#define LAGG_RLOCK_ASSERT(_sc) rw_assert(&(_sc)->sc_mtx, RA_RLOCKED)
-#define LAGG_WLOCK_ASSERT(_sc) rw_assert(&(_sc)->sc_mtx, RA_WLOCKED)
+#define LAGG_LOCK_INIT(_sc) rm_init(&(_sc)->sc_mtx, "if_lagg
rmlock")
+#define LAGG_LOCK_DESTROY(_sc) rm_destroy(&(_sc)->sc_mtx)
+#define LAGG_RLOCK(_sc, _p) rm_rlock(&(_sc)->sc_mtx, (_p))
+#define LAGG_WLOCK(_sc) rm_wlock(&(_sc)->sc_mtx)
+#define LAGG_RUNLOCK(_sc, _p) rm_runlock(&(_sc)->sc_mtx, (_p))
+#define LAGG_WUNLOCK(_sc) rm_wunlock(&(_sc)->sc_mtx)
+#define LAGG_RLOCK_ASSERT(_sc) rm_assert(&(_sc)->sc_mtx, RA_RLOCKED)
+#define LAGG_WLOCK_ASSERT(_sc) rm_assert(&(_sc)->sc_mtx, RA_WLOCKED)
+
+#define LAGG_CALLOUT_LOCK_INIT(_sc)
\
+ mtx_init(&(_sc)->sc_call_mtx, "if_lagg callout mutex", NULL,\
+ MTX_DEF)
+#define LAGG_CALLOUT_LOCK_DESTROY(_sc) mtx_destroy(&(_sc)->sc_call_mtx)
extern struct mbuf *(*lagg_input_p)(struct ifnet *, struct mbuf *);
extern void (*lagg_linkstate_p)(struct ifnet *, int );
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