>Number: 164901
>Category: kern
>Synopsis: [regression] [patch] [lagg] igb/lagg poor traffic distribution
>Confidential: no
>Severity: serious
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Feb 08 09:00:20 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Eugene Grosbein
>Release: FreeBSD 8.2-STABLE i386
>Organization:
RDTC JSC
>Environment:
System: FreeBSD eg.sd.rdtc.ru 8.2-STABLE FreeBSD 8.2-STABLE #36: Fri Dec 23
15:04:05 NOVT 2011 r...@eg.sd.rdtc.ru:/usr/local/obj/usr/local/src/sys/EG i386
>Description:
Suppose, we have a router (BRAS) using two lagg(4) interfaces in LACP
mode.
Two-port lagg0 has IP address and its ports carry untagged IPoE frames.
lagg1 has no IP address and has two ports (82576-based igb0 and igb1)
that carry 1000 dot-q vlans with PPPoE frames only.
In RELENG_7, lagg(4) evenly distributes traffic going from lagg1 to
lagg0.
Since 8.0-RELEASE all this traffic goes out through one of lagg0's
ports only.
82576-based NICs and igb(4) support Microsoft Receive-Side Scaling
(RSS),
see
http://download.intel.com/design/network/datashts/82576_Datasheet.pdf
RSS states that queue number for non-IP frames (PPPoE/GRE/etc.)
is not computed with hash. So, all these frames get same (zero)
queue number and igb(4) assigns tag M_FLOWID=0 to mbufs.
Since 8.0-RELEASE, lagg(4) skips its own hash computation for mbuts
having M_FLOWID tag attached. Hence, it directs all such traffic
to its first port only in this setup.
>How-To-Repeat:
See above.
>Fix:
The following patch fixes the regression by introducing new sysctls
that disable usage of M_FLOWID per lagg interface:
net.link.lagg.0.use_flowid
net.link.lagg.1.use_flowid
Default value is 1 that corresponds to current behaviour of lagg(4).
To fix our issue, we set net.link.lagg.0.use_flowid=0
that restores pre-8 behaviour for lagg0 only, so it ignores misleading
M_FLOWID assigned to mbufs by lagg1's ports.
--- sys/net/if_lagg.h.orig 2010-12-27 12:59:59.000000000 +0600
+++ sys/net/if_lagg.h 2012-01-23 16:34:15.000000000 +0700
@@ -21,6 +21,8 @@
#ifndef _NET_LAGG_H
#define _NET_LAGG_H
+#include <sys/sysctl.h>
+
/*
* Global definitions
*/
@@ -202,6 +204,8 @@ struct lagg_softc {
eventhandler_tag vlan_attach;
eventhandler_tag vlan_detach;
#endif
+ struct sysctl_ctx_list ctx; /* sysctl variables */
+ int use_flowid; /* use M_FLOWID */
};
struct lagg_port {
--- sys/net/if_lagg.c.orig 2011-08-08 19:16:42.000000000 +0700
+++ sys/net/if_lagg.c 2012-01-23 16:33:04.000000000 +0700
@@ -257,6 +257,8 @@ lagg_clone_create(struct if_clone *ifc,
struct ifnet *ifp;
int i, error = 0;
static const u_char eaddr[6]; /* 00:00:00:00:00:00 */
+ struct sysctl_oid *oid;
+ char num[14]; /* sufficient for 32 bits */
sc = malloc(sizeof(*sc), M_DEVBUF, M_WAITOK|M_ZERO);
ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
@@ -265,6 +267,15 @@ lagg_clone_create(struct if_clone *ifc,
return (ENOSPC);
}
+ sysctl_ctx_init(&sc->ctx);
+ snprintf(num, sizeof(num), "%u", unit);
+ sc->use_flowid = 1;
+ oid = SYSCTL_ADD_NODE(&sc->ctx, &SYSCTL_NODE_CHILDREN(_net_link, lagg),
+ OID_AUTO, num, CTLFLAG_RD, NULL, "");
+ SYSCTL_ADD_INT(&sc->ctx, SYSCTL_CHILDREN(oid), OID_AUTO,
+ "use_flowid", CTLTYPE_INT|CTLFLAG_RW, &sc->use_flowid,
sc->use_flowid,
+ "Use flow id for load sharing");
+
sc->sc_proto = LAGG_PROTO_NONE;
for (i = 0; lagg_protos[i].ti_proto != LAGG_PROTO_NONE; i++) {
if (lagg_protos[i].ti_proto == LAGG_PROTO_DEFAULT) {
@@ -344,6 +355,7 @@ lagg_clone_destroy(struct ifnet *ifp)
LAGG_WUNLOCK(sc);
+ sysctl_ctx_free(&sc->ctx);
ifmedia_removeall(&sc->sc_media);
ether_ifdetach(ifp);
if_free_type(ifp, IFT_ETHER);
@@ -1668,7 +1680,7 @@ lagg_lb_start(struct lagg_softc *sc, str
struct lagg_port *lp = NULL;
uint32_t p = 0;
- if (m->m_flags & M_FLOWID)
+ if (sc->use_flowid && (m->m_flags & M_FLOWID))
p = m->m_pkthdr.flowid;
else
p = lagg_hashmbuf(m, lb->lb_key);
--- sys/net/ieee8023ad_lacp.c.orig 2009-08-03 16:13:06.000000000 +0800
+++ sys/net/ieee8023ad_lacp.c 2012-01-23 13:44:00.000000000 +0700
@@ -812,7 +812,7 @@ lacp_select_tx_port(struct lagg_softc *s
return (NULL);
}
- if (m->m_flags & M_FLOWID)
+ if (sc->use_flowid && (m->m_flags & M_FLOWID))
hash = m->m_pkthdr.flowid;
else
hash = lagg_hashmbuf(m, lsc->lsc_hashkey);
>Release-Note:
>Audit-Trail:
>Unformatted:
_______________________________________________
freebsd-bugs@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-bugs
To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
