From 4b29d585cfcde7e84697e4af66a48144fb111e27 Mon Sep 17 00:00:00 2001 From: glebius Date: Fri, 28 Sep 2012 18:28:27 +0000 Subject: The drbr(9) API appeared to be so unclear, that most drivers in tree used it incorrectly, which lead to inaccurate overrated if_obytes accounting. The drbr(9) used to update ifnet stats on drbr_enqueue(), which is not accurate since enqueuing doesn't imply successful processing by driver. Dequeuing neither mean that. Most drivers also called drbr_stats_update() which did accounting again, leading to doubled if_obytes statistics. And in case of severe transmitting, when a packet could be several times enqueued and dequeued it could have been accounted several times. o Thus, make drbr(9) API thinner. Now drbr(9) merely chooses between ALTQ queueing or buf_ring(9) queueing. - It doesn't touch the buf_ring stats any more. - It doesn't touch ifnet stats anymore. - drbr_stats_update() no longer exists. o buf_ring(9) handles its stats itself: - It handles br_drops itself. - br_prod_bytes stats are dropped. Rationale: no one ever reads them but update of a common counter on every packet negatively affects performance due to excessive cache invalidation. - buf_ring_enqueue_bytes() reduced to buf_ring_enqueue(), since we no longer account bytes. o Drivers handle their stats theirselves: if_obytes, if_omcasts. o mlx4(4), igb(4), em(4), vxge(4), oce(4) and ixv(4) no longer use drbr_stats_update(), and update ifnet stats theirselves. o bxe(4) was the most correct driver, it didn't call drbr_stats_update(), thus it was the only driver accurate under moderate load. Now it also maintains stats itself. o ixgbe(4) had already taken stats from hardware, so just - drop software stats updating. - take multicast packet count from hardware as well. o mxge(4) just no longer needs NO_SLOW_STATS define. o cxgb(4), cxgbe(4) need no change, since they obtain stats from hardware. Reviewed by: jfv, gnn --- sys/net/if_var.h | 20 +++----------------- 1 file changed, 3 insertions(+), 17 deletions(-) (limited to 'sys/net') diff --git a/sys/net/if_var.h b/sys/net/if_var.h index 01ec2b6..8a1d5cc 100644 --- a/sys/net/if_var.h +++ b/sys/net/if_var.h @@ -590,22 +590,10 @@ do { \ } while (0) #ifdef _KERNEL -static __inline void -drbr_stats_update(struct ifnet *ifp, int len, int mflags) -{ -#ifndef NO_SLOW_STATS - ifp->if_obytes += len; - if (mflags & M_MCAST) - ifp->if_omcasts++; -#endif -} - static __inline int drbr_enqueue(struct ifnet *ifp, struct buf_ring *br, struct mbuf *m) { int error = 0; - int len = m->m_pkthdr.len; - int mflags = m->m_flags; #ifdef ALTQ if (ALTQ_IS_ENABLED(&ifp->if_snd)) { @@ -613,12 +601,10 @@ drbr_enqueue(struct ifnet *ifp, struct buf_ring *br, struct mbuf *m) return (error); } #endif - if ((error = buf_ring_enqueue_bytes(br, m, len)) == ENOBUFS) { - br->br_drops++; + error = buf_ring_enqueue(br, m); + if (error) m_freem(m); - } else - drbr_stats_update(ifp, len, mflags); - + return (error); } -- cgit v1.1