lagg/lacp poor traffic distribution

[Eugene Grosbein]

On 20.12.2010 17:21, Shtorm wrote:

> I had this problem with igb driver, and I found, that lagg selects
> outgoing interface based on packet header flowid field if M_FLOWID field
> is set. And in the igb driver code flowid is set as 
> 
> #if __FreeBSD_version >= 800000
> <------><------><------>rxr->fmp->m_pkthdr.flowid = que->msix;
> <------><------><------>rxr->fmp->m_flags |= M_FLOWID;
> #endif
> 
> The same thing in em driver with MULTIQUEUE 
> 
> That does not give enough number of flows to balance traffic well, so I
> commented check in if_lagg.c
> 
> lagg_lb_start(struct lagg_softc *sc, struct mbuf *m)
> {
> <------>struct lagg_lb *lb = (struct lagg_lb *)sc->sc_psc;
> <------>struct lagg_port *lp = NULL;
> <------>uint32_t p = 0;
> 
> //<---->if (m->m_flags & M_FLOWID)
> //<----><------>p = m->m_pkthdr.flowid;
> //<---->else
> 
> and with this change I have much better load distribution across interfaces.
> 
> Hope it helps.
> 

I've made new sysctl net.link.lagg.use_flows to enable/disable
this code in run time and disabled it. No change.

--- if_lagg.c.orig	2010-12-20 22:53:21.000000000 +0600
+++ if_lagg.c	2010-12-20 22:57:50.000000000 +0600
@@ -168,6 +168,11 @@
     &lagg_failover_rx_all, 0,
     "Accept input from any interface in a failover lagg");
 
+static int lagg_use_flows = 1;
+SYSCTL_INT(_net_link_lagg, OID_AUTO, use_flows, CTLFLAG_RW,
+    &lagg_use_flows, 1,
+    "Use flows for load sharing");
+
 static int
 lagg_modevent(module_t mod, int type, void *data)
 {
@@ -1666,7 +1671,7 @@
 	struct lagg_port *lp = NULL;
 	uint32_t p = 0;
 
-	if (m->m_flags & M_FLOWID)
+	if (lagg_use_flows && (m->m_flags & M_FLOWID))
 		p = m->m_pkthdr.flowid;
 	else
 		p = lagg_hashmbuf(m, lb->lb_key);