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
This commit is contained in:
parent
a1c9ec3ce0
commit
063efed28c
@ -25,7 +25,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 30, 2012
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.Dd September 27, 2012
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.Dt BUF_RING 9
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.Os
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.Sh NAME
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@ -33,7 +33,6 @@
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.Nm buf_ring_alloc ,
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.Nm buf_ring_free ,
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.Nm buf_ring_enqueue ,
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.Nm buf_ring_enqueue_bytes ,
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.Nm buf_ring_dequeue_mc ,
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.Nm buf_ring_dequeue_sc ,
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.Nm buf_ring_count ,
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@ -50,8 +49,6 @@
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.Fn buf_ring_free "struct buf_ring *br" "struct malloc_type *type"
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.Ft int
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.Fn buf_ring_enqueue "struct buf_ring *br" "void *buf"
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.Ft int
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.Fn buf_ring_enqueue_bytes "struct buf_ring *br" "void *buf" "int bytes"
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.Ft void *
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.Fn buf_ring_dequeue_mc "struct buf_ring *br"
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.Ft void *
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@ -91,12 +88,6 @@ The
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function is used to enqueue a buffer to a buf_ring.
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.Pp
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The
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.Fn buf_ring_enqueue_bytes
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function is used to enqueue a buffer to a buf_ring and increment the
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number of bytes enqueued by
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.Fa bytes .
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.Pp
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The
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.Fn buf_ring_dequeue_mc
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function is a multi-consumer safe way of dequeueing elements from a buf_ring.
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.Pp
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@ -134,9 +125,7 @@ otherwise.
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.Sh RETURN VALUES
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The
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.Fn buf_ring_enqueue
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and
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.Fn buf_ring_enqueue_bytes
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functions return
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function return
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.Er ENOBUFS
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if there are no available slots in the buf_ring.
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.Sh HISTORY
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@ -25,7 +25,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 30, 2012
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.Dd September 27, 2012
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.Dt DRBR 9
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.Os
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.Sh NAME
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@ -37,7 +37,6 @@
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.Nm drbr_flush ,
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.Nm drbr_empty ,
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.Nm drbr_inuse ,
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.Nm drbr_stats_update ,
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.Nd network driver interface to buf_ring
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.Sh SYNOPSIS
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.In sys/param.h
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@ -57,8 +56,6 @@
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.Fn drbr_empty "struct ifnet *ifp" "struct buf_ring *br"
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.Ft int
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.Fn drbr_inuse "struct ifnet *ifp" "struct buf_ring *br"
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.Ft void
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.Fn drbr_stats_update "struct ifnet *ifp" "int len" "int mflags"
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.Sh DESCRIPTION
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The
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.Nm
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@ -123,9 +120,6 @@ there will not be more mbufs when
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is actually called.
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Provided the tx queue lock is held there will not be less.
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.Pp
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The
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.Fn drbr_stats_update
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function updates the number of bytes and the number of multicast packets sent.
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.Sh RETURN VALUES
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The
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.Fn drbr_enqueue
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@ -9557,6 +9557,11 @@ bxe_tx_mq_start_locked(struct ifnet *ifp,
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/* The transmit frame was enqueued successfully. */
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tx_count++;
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/* Update stats */
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ifp->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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ifp->if_omcasts++;
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/* Send a copy of the frame to any BPF listeners. */
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BPF_MTAP(ifp, next);
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@ -922,7 +922,9 @@ em_mq_start_locked(struct ifnet *ifp, struct tx_ring *txr, struct mbuf *m)
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break;
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}
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enq++;
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drbr_stats_update(ifp, next->m_pkthdr.len, next->m_flags);
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ifp->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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ifp->if_omcasts++;
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ETHER_BPF_MTAP(ifp, next);
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if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0)
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break;
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@ -1014,7 +1014,9 @@ igb_mq_start_locked(struct ifnet *ifp, struct tx_ring *txr, struct mbuf *m)
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break;
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}
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enq++;
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drbr_stats_update(ifp, next->m_pkthdr.len, next->m_flags);
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ifp->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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ifp->if_omcasts++;
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ETHER_BPF_MTAP(ifp, next);
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if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0)
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break;
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@ -853,7 +853,6 @@ ixgbe_mq_start_locked(struct ifnet *ifp, struct tx_ring *txr, struct mbuf *m)
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break;
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}
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enqueued++;
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drbr_stats_update(ifp, next->m_pkthdr.len, next->m_flags);
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/* Send a copy of the frame to the BPF listener */
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ETHER_BPF_MTAP(ifp, next);
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if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0)
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@ -5335,6 +5334,7 @@ ixgbe_update_stats_counters(struct adapter *adapter)
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ifp->if_ibytes = adapter->stats.gorc;
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ifp->if_obytes = adapter->stats.gotc;
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ifp->if_imcasts = adapter->stats.mprc;
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ifp->if_omcasts = adapter->stats.mptc;
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ifp->if_collisions = 0;
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/* Rx Errors */
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@ -641,7 +641,9 @@ ixv_mq_start_locked(struct ifnet *ifp, struct tx_ring *txr, struct mbuf *m)
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break;
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}
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enqueued++;
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drbr_stats_update(ifp, next->m_pkthdr.len, next->m_flags);
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ifp->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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ifp->if_omcasts++;
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/* Send a copy of the frame to the BPF listener */
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ETHER_BPF_MTAP(ifp, next);
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if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0)
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@ -47,8 +47,6 @@ __FBSDID("$FreeBSD$");
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#include <sys/sx.h>
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#include <sys/taskqueue.h>
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/* count xmits ourselves, rather than via drbr */
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#define NO_SLOW_STATS
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#include <net/if.h>
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#include <net/if_arp.h>
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#include <net/ethernet.h>
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}
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break;
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}
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drbr_stats_update(ifp, next->m_pkthdr.len, next->m_flags);
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ifp->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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ifp->if_omcasts++;
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ETHER_BPF_MTAP(ifp, next);
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next = drbr_dequeue(ifp, br);
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}
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VXGE_DRV_STATS(vpath, tx_again);
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break;
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}
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drbr_stats_update(ifp, next->m_pkthdr.len, next->m_flags);
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ifp->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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ifp->if_omcasts++;
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/* Send a copy of the frame to the BPF listener */
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ETHER_BPF_MTAP(ifp, next);
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} while (0)
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#ifdef _KERNEL
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static __inline void
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drbr_stats_update(struct ifnet *ifp, int len, int mflags)
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{
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#ifndef NO_SLOW_STATS
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ifp->if_obytes += len;
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if (mflags & M_MCAST)
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ifp->if_omcasts++;
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#endif
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}
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static __inline int
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drbr_enqueue(struct ifnet *ifp, struct buf_ring *br, struct mbuf *m)
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{
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int error = 0;
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int len = m->m_pkthdr.len;
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int mflags = m->m_flags;
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#ifdef ALTQ
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if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
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@ -613,12 +601,10 @@ drbr_enqueue(struct ifnet *ifp, struct buf_ring *br, struct mbuf *m)
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return (error);
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}
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#endif
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if ((error = buf_ring_enqueue_bytes(br, m, len)) == ENOBUFS) {
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br->br_drops++;
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error = buf_ring_enqueue(br, m);
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if (error)
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m_freem(m);
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} else
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drbr_stats_update(ifp, len, mflags);
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return (error);
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}
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break;
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}
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enqueued++;
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drbr_stats_update(dev, next->m_pkthdr.len, next->m_flags);
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dev->if_obytes += next->m_pkthdr.len;
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if (next->m_flags & M_MCAST)
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dev->if_omcasts++;
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/* Send a copy of the frame to the BPF listener */
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ETHER_BPF_MTAP(dev, next);
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if ((dev->if_drv_flags & IFF_DRV_RUNNING) == 0)
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int br_prod_mask;
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uint64_t br_drops;
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uint64_t br_prod_bufs;
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uint64_t br_prod_bytes;
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/*
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* Pad out to next L2 cache line
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*/
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@ -74,7 +73,7 @@ struct buf_ring {
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*
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*/
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static __inline int
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buf_ring_enqueue_bytes(struct buf_ring *br, void *buf, int nbytes)
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buf_ring_enqueue(struct buf_ring *br, void *buf)
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{
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uint32_t prod_head, prod_next;
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uint32_t cons_tail;
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@ -95,6 +94,7 @@ buf_ring_enqueue_bytes(struct buf_ring *br, void *buf, int nbytes)
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prod_next = (prod_head + 1) & br->br_prod_mask;
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if (prod_next == cons_tail) {
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br->br_drops++;
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critical_exit();
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return (ENOBUFS);
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}
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@ -117,19 +117,11 @@ buf_ring_enqueue_bytes(struct buf_ring *br, void *buf, int nbytes)
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while (br->br_prod_tail != prod_head)
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cpu_spinwait();
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br->br_prod_bufs++;
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br->br_prod_bytes += nbytes;
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br->br_prod_tail = prod_next;
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critical_exit();
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return (0);
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}
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static __inline int
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buf_ring_enqueue(struct buf_ring *br, void *buf)
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{
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return (buf_ring_enqueue_bytes(br, buf, 0));
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}
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/*
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* multi-consumer safe dequeue
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*
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