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Index: share/man/man4/epair.4
===================================================================
--- share/man/man4/epair.4
+++ share/man/man4/epair.4
@@ -28,7 +28,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd March 18, 2015
+.Dd March 11, 2020
.Dt EPAIR 4
.Os
.Sh NAME
@@ -99,6 +99,48 @@
can have a
.Xr vlan 4
configured on top of it.
+.Sh LOADER TUNABLES
+Tunables can be set at the
+.Xr loader 8
+prompt before booting the kernel, or stored in
+.Xr loader.conf 5 .
+.Bl -tag -width indent
+.It Va net.isr.bindthreads Pq Defaults to 0
+If running multi-CPU configurations is is advised to turn this to
+.Ql 1
+along with the next option adjusted as well.
+.It Va net.isr.maxthreads Pq Defaults to 1
+If running a multi-CPU configration with a lot of
+.Nm
+interfaces it is advisable to set this number to the current number of
+CPUs or a high number (as
+.Xr netisr 9
+will automatically reduce it to the maximum number).
+.It Va net.link.epair.netisr_maxqlen Pq Defaults to 256
+If running a high number of
+.Nm
+interfaces it is advisable to adjust this value to the
+.Xr netisr 9
+maximum queue length of
+.Ql 10240 .
+This allows interfaces to queue more packets per CPU and with that
+usually avoids queue drops.
+.El
+.Pp
+All tunables are related to the
+.Xr netisr 9
+functionality used by
+.Nm
+and should help scaling to larger systems.
+.Sh BUGS
+.Nm
+interfaces used to stall once the hardware queue was overflown.
+The functionality of draining per-interfaces queues is currently
+disabled.
+.Pp
+.Nm
+has scaling problems on modern systems with mass-deployment and
+needs to be reworked.
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr altq 4 ,
@@ -107,7 +149,8 @@
.Xr vlan 4 ,
.Xr loader.conf 5 ,
.Xr rc.conf 5 ,
-.Xr ifconfig 8
+.Xr ifconfig 8 ,
+.Xr netisr 9
.Sh HISTORY
The
.Nm
Index: sys/net/if_epair.c
===================================================================
--- sys/net/if_epair.c
+++ sys/net/if_epair.c
@@ -97,7 +97,9 @@
static void epair_nh_sintr(struct mbuf *);
static struct mbuf *epair_nh_m2cpuid(struct mbuf *, uintptr_t, u_int *);
+#ifdef EPAIR_DRAIN
static void epair_nh_drainedcpu(u_int);
+#endif
static void epair_start_locked(struct ifnet *);
static int epair_media_change(struct ifnet *);
@@ -117,7 +119,9 @@
.nh_policy = NETISR_POLICY_CPU,
.nh_handler = epair_nh_sintr,
.nh_m2cpuid = epair_nh_m2cpuid,
+#ifdef EPAIR_DRAIN
.nh_drainedcpu = epair_nh_drainedcpu,
+#endif
};
static int
@@ -148,6 +152,7 @@
/* Original if_qflush routine. */
};
+#ifdef EPAIR_DRAIN
/*
* Per-CPU list of ifps with data in the ifq that needs to be flushed
* to the netisr ``hw'' queue before we allow any further direct queuing
@@ -158,6 +163,7 @@
struct ifnet *ifp;
};
STAILQ_HEAD(eid_list, epair_ifp_drain);
+#endif
#define EPAIR_LOCK_INIT(dpcpu) mtx_init(&(dpcpu)->if_epair_mtx, \
"if_epair", NULL, MTX_DEF)
@@ -191,8 +197,10 @@
struct epair_dpcpu {
struct mtx if_epair_mtx; /* Per-CPU locking. */
int epair_drv_flags; /* Per-CPU ``hw'' drv flags. */
+#ifdef EPAIR_DRAIN
struct eid_list epair_ifp_drain_list; /* Per-CPU list of ifps with
* data in the ifq. */
+#endif
};
DPCPU_DEFINE(struct epair_dpcpu, epair_dpcpu);
@@ -200,7 +208,9 @@
epair_dpcpu_init(void)
{
struct epair_dpcpu *epair_dpcpu;
+#ifdef EPAIR_DRAIN
struct eid_list *s;
+#endif
u_int cpuid;
CPU_FOREACH(cpuid) {
@@ -212,6 +222,7 @@
/* Driver flags are per-cpu as are our netisr "hw" queues. */
epair_dpcpu->epair_drv_flags = 0;
+#ifdef EPAIR_DRAIN
/*
* Initialize per-cpu drain list.
* Manually do what STAILQ_HEAD_INITIALIZER would do.
@@ -219,6 +230,7 @@
s = &epair_dpcpu->epair_ifp_drain_list;
s->stqh_first = NULL;
s->stqh_last = &s->stqh_first;
+#endif
}
}
@@ -279,6 +291,7 @@
return (m);
}
+#ifdef EPAIR_DRAIN
static void
epair_nh_drainedcpu(u_int cpuid)
{
@@ -327,10 +340,12 @@
}
EPAIR_UNLOCK(epair_dpcpu);
}
+#endif
/*
* Network interface (`if') related functions.
*/
+#ifdef EPAIR_DRAIN
static void
epair_remove_ifp_from_draining(struct ifnet *ifp)
{
@@ -390,6 +405,7 @@
return (0);
}
+#endif
static void
epair_start_locked(struct ifnet *ifp)
@@ -450,14 +466,16 @@
if_inc_counter(oifp, IFCOUNTER_IPACKETS, 1);
} else {
/* The packet was freed already. */
+ if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
+#ifdef EPAIR_DRAIN
epair_dpcpu->epair_drv_flags |= IFF_DRV_OACTIVE;
ifp->if_drv_flags |= IFF_DRV_OACTIVE;
(void) epair_add_ifp_for_draining(ifp);
- if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
EPAIR_REFCOUNT_RELEASE(&sc->refcount);
EPAIR_REFCOUNT_ASSERT((int)sc->refcount >= 1,
("%s: ifp=%p sc->refcount not >= 1: %d",
__func__, oifp, sc->refcount));
+#endif
}
}
}
@@ -535,16 +553,21 @@
if (mflags & (M_BCAST|M_MCAST))
if_inc_counter(ifp, IFCOUNTER_OMCASTS, 1);
+#ifdef EPAIR_DRAIN
if ((ifp->if_drv_flags & IFF_DRV_OACTIVE) == 0)
+#endif
epair_start_locked(ifp);
+#ifdef EPAIR_DRAIN
else
(void)epair_add_ifp_for_draining(ifp);
+#endif
}
return (error);
}
IF_UNLOCK(&ifp->if_snd);
#endif
+#ifdef EPAIR_DRAIN
if ((epair_dpcpu->epair_drv_flags & IFF_DRV_OACTIVE) != 0) {
/*
* Our hardware queue is full, try to fall back
@@ -556,6 +579,7 @@
(void)epair_add_ifp_for_draining(ifp);
return (error);
}
+#endif
sc = oifp->if_softc;
/*
* Add a reference so the interface cannot go while the
@@ -580,13 +604,15 @@
if_inc_counter(oifp, IFCOUNTER_IPACKETS, 1);
} else {
/* The packet was freed already. */
+ if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
+#ifdef EPAIR_DRAIN
epair_dpcpu->epair_drv_flags |= IFF_DRV_OACTIVE;
ifp->if_drv_flags |= IFF_DRV_OACTIVE;
- if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
EPAIR_REFCOUNT_RELEASE(&sc->refcount);
EPAIR_REFCOUNT_ASSERT((int)sc->refcount >= 1,
("%s: ifp=%p sc->refcount not >= 1: %d",
__func__, oifp, sc->refcount));
+#endif
}
return (error);
@@ -613,12 +639,14 @@
sc = ifp->if_softc;
KASSERT(sc != NULL, ("%s: ifp=%p, epair_softc gone? sc=%p\n",
__func__, ifp, sc));
+#ifdef EPAIR_DRAIN
/*
* Remove this ifp from all backpointer lists. The interface will not
* usable for flushing anyway nor should it have anything to flush
* after if_qflush().
*/
epair_remove_ifp_from_draining(ifp);
+#endif
if (sc->if_qflush)
sc->if_qflush(ifp);

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