Author: scottl
Date: Thu Jan 2 01:51:54 2014
New Revision: 260179
URL: http://svnweb.freebsd.org/changeset/base/260179
Log:
MFC r260070
Multi-queue NIC drivers and multi-port lagg tend to use the same lower
bits of the flowid as each other, resulting in a poor distribution of
packets among queues in certain cases. Work around this by adding a
set of sysctls for controlling a bit-shift on the flowid when doing
multi-port aggrigation in lagg and lacp. By default, lagg/lacp will
now use bits 16 and higher instead of 0 and higher.
Obtained from: Netflix
Modified:
stable/10/sys/net/ieee8023ad_lacp.c
stable/10/sys/net/if_lagg.c
stable/10/sys/net/if_lagg.h
Directory Properties:
stable/10/ (props changed)
Modified: stable/10/sys/net/ieee8023ad_lacp.c
==============================================================================
--- stable/10/sys/net/ieee8023ad_lacp.c Thu Jan 2 01:44:14 2014
(r260178)
+++ stable/10/sys/net/ieee8023ad_lacp.c Thu Jan 2 01:51:54 2014
(r260179)
@@ -874,7 +874,7 @@ lacp_select_tx_port(struct lagg_softc *s
}
if (sc->use_flowid && (m->m_flags & M_FLOWID))
- hash = m->m_pkthdr.flowid;
+ hash = m->m_pkthdr.flowid >> sc->flowid_shift;
else
hash = lagg_hashmbuf(sc, m, lsc->lsc_hashkey);
hash %= pm->pm_count;
Modified: stable/10/sys/net/if_lagg.c
==============================================================================
--- stable/10/sys/net/if_lagg.c Thu Jan 2 01:44:14 2014 (r260178)
+++ stable/10/sys/net/if_lagg.c Thu Jan 2 01:51:54 2014 (r260179)
@@ -184,6 +184,11 @@ TUNABLE_INT("net.link.lagg.default_use_f
SYSCTL_INT(_net_link_lagg, OID_AUTO, default_use_flowid, CTLFLAG_RW,
&def_use_flowid, 0,
"Default setting for using flow id for load sharing");
+static int def_flowid_shift = 16; /* Default value for using M_FLOWID */
+TUNABLE_INT("net.link.lagg.default_flowid_shift", &def_flowid_shift);
+SYSCTL_INT(_net_link_lagg, OID_AUTO, default_flowid_shift, CTLFLAG_RW,
+ &def_flowid_shift, 0,
+ "Default setting for flowid shift for load sharing");
static int
lagg_modevent(module_t mod, int type, void *data)
@@ -293,12 +298,17 @@ lagg_clone_create(struct if_clone *ifc,
sysctl_ctx_init(&sc->ctx);
snprintf(num, sizeof(num), "%u", unit);
sc->use_flowid = def_use_flowid;
+ sc->flowid_shift = def_flowid_shift;
sc->sc_oid = 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");
+ "use_flowid", CTLTYPE_INT|CTLFLAG_RW, &sc->use_flowid,
+ sc->use_flowid, "Use flow id for load sharing");
+ SYSCTL_ADD_INT(&sc->ctx, SYSCTL_CHILDREN(oid), OID_AUTO,
+ "flowid_shift", CTLTYPE_INT|CTLFLAG_RW, &sc->flowid_shift,
+ sc->flowid_shift,
+ "Shift flowid bits to prevent multiqueue collisions");
SYSCTL_ADD_INT(&sc->ctx, SYSCTL_CHILDREN(oid), OID_AUTO,
"count", CTLTYPE_INT|CTLFLAG_RD, &sc->sc_count, sc->sc_count,
"Total number of ports");
@@ -1850,7 +1860,7 @@ lagg_lb_start(struct lagg_softc *sc, str
uint32_t p = 0;
if (sc->use_flowid && (m->m_flags & M_FLOWID))
- p = m->m_pkthdr.flowid;
+ p = m->m_pkthdr.flowid >> sc->flowid_shift;
else
p = lagg_hashmbuf(sc, m, lb->lb_key);
p %= sc->sc_count;
Modified: stable/10/sys/net/if_lagg.h
==============================================================================
--- stable/10/sys/net/if_lagg.h Thu Jan 2 01:44:14 2014 (r260178)
+++ stable/10/sys/net/if_lagg.h Thu Jan 2 01:51:54 2014 (r260179)
@@ -231,6 +231,7 @@ struct lagg_softc {
struct sysctl_ctx_list ctx; /* sysctl variables */
struct sysctl_oid *sc_oid; /* sysctl tree oid */
int use_flowid; /* use M_FLOWID */
+ int flowid_shift; /* shift the flowid */
};
struct lagg_port {
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