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Pass the number of segments coalesced by LRO up the stack by repurposing the

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tso_segsz pkthdr field during RX processing, and use the information in TCP for
more correct accounting and as a congestion control input. This is only a start,
and an audit of other uses for the data is left as future work.

Reviewed by:	gallatin, rrs
Sponsored by:	Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D7564
This commit is contained in:
Lawrence Stewart 2016-08-25 13:33:32 +00:00
parent eb27c4c0e9
commit 4b7b743c16
6 changed files with 23 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
sys/netinet/cc/cc.h
View File

@ -86,6 +86,7 @@ struct cc_var {
struct tcpcb *tcp;
struct sctp_nets *sctp;
} ccvc;
uint16_t nsegs; /* # segments coalesced into current chain. */
};
/* cc_var flags. */

3
sys/netinet/cc/cc_newreno.c
View File

@ -137,7 +137,8 @@ newreno_ack_received(struct cc_var *ccv, uint16_t type)
*/
if (CCV(ccv, snd_nxt) == CCV(ccv, snd_max))
incr = min(ccv->bytes_this_ack,
V_tcp_abc_l_var * CCV(ccv, t_maxseg));
ccv->nsegs * V_tcp_abc_l_var *
CCV(ccv, t_maxseg));
else
incr = min(ccv->bytes_this_ack, CCV(ccv, t_maxseg));
}

27
sys/netinet/tcp_input.c
View File

@ -300,10 +300,12 @@ hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to)
* CC wrapper hook functions
*/
void
cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t type)
cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs,
uint16_t type)
{
INP_WLOCK_ASSERT(tp->t_inpcb);
tp->ccv->nsegs = nsegs;
tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th);
if (tp->snd_cwnd <= tp->snd_wnd)
tp->ccv->flags |= CCF_CWND_LIMITED;
@ -313,7 +315,7 @@ cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t type)
if (type == CC_ACK) {
if (tp->snd_cwnd > tp->snd_ssthresh) {
tp->t_bytes_acked += min(tp->ccv->bytes_this_ack,
V_tcp_abc_l_var * tcp_maxseg(tp));
nsegs * V_tcp_abc_l_var * tcp_maxseg(tp));
if (tp->t_bytes_acked >= tp->snd_cwnd) {
tp->t_bytes_acked -= tp->snd_cwnd;
tp->ccv->flags |= CCF_ABC_SENTAWND;
@ -1502,6 +1504,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
int thflags, acked, ourfinisacked, needoutput = 0, sack_changed;
int rstreason, todrop, win;
u_long tiwin;
uint16_t nsegs;
char *s;
struct in_conninfo *inc;
struct mbuf *mfree;
@ -1521,6 +1524,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
inc = &tp->t_inpcb->inp_inc;
tp->sackhint.last_sack_ack = 0;
sack_changed = 0;
nsegs = max(1, m->m_pkthdr.lro_nsegs);
/*
* If this is either a state-changing packet or current state isn't
@ -1759,7 +1763,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
/* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */
hhook_run_tcp_est_in(tp, th, &to);
TCPSTAT_INC(tcps_rcvackpack);
TCPSTAT_ADD(tcps_rcvackpack, nsegs);
TCPSTAT_ADD(tcps_rcvackbyte, acked);
sbdrop(&so->so_snd, acked);
if (SEQ_GT(tp->snd_una, tp->snd_recover) &&
@ -1772,7 +1776,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
* typically means increasing the congestion
* window.
*/
cc_ack_received(tp, th, CC_ACK);
cc_ack_received(tp, th, nsegs, CC_ACK);
tp->snd_una = th->th_ack;
/*
@ -1838,7 +1842,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
* rcv_nxt.
*/
tp->rcv_up = tp->rcv_nxt;
TCPSTAT_INC(tcps_rcvpack);
TCPSTAT_ADD(tcps_rcvpack, nsegs);
TCPSTAT_ADD(tcps_rcvbyte, tlen);
#ifdef TCPDEBUG
if (so->so_options & SO_DEBUG)
@ -2570,7 +2574,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
tp->t_dupacks = 0;
else if (++tp->t_dupacks > tcprexmtthresh ||
IN_FASTRECOVERY(tp->t_flags)) {
cc_ack_received(tp, th, CC_DUPACK);
cc_ack_received(tp, th, nsegs,
CC_DUPACK);
if ((tp->t_flags & TF_SACK_PERMIT) &&
IN_FASTRECOVERY(tp->t_flags)) {
int awnd;
@ -2620,7 +2625,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
}
/* Congestion signal before ack. */
cc_cong_signal(tp, th, CC_NDUPACK);
cc_ack_received(tp, th, CC_DUPACK);
cc_ack_received(tp, th, nsegs,
CC_DUPACK);
tcp_timer_activate(tp, TT_REXMT, 0);
tp->t_rtttime = 0;
if (tp->t_flags & TF_SACK_PERMIT) {
@ -2654,7 +2660,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
* segment. Restore the original
* snd_cwnd after packet transmission.
*/
cc_ack_received(tp, th, CC_DUPACK);
cc_ack_received(tp, th, nsegs,
CC_DUPACK);
u_long oldcwnd = tp->snd_cwnd;
tcp_seq oldsndmax = tp->snd_max;
u_int sent;
@ -2756,7 +2763,7 @@ process_ACK:
KASSERT(acked >= 0, ("%s: acked unexepectedly negative "
"(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__,
tp->snd_una, th->th_ack, tp, m));
TCPSTAT_INC(tcps_rcvackpack);
TCPSTAT_ADD(tcps_rcvackpack, nsegs);
TCPSTAT_ADD(tcps_rcvackbyte, acked);
/*
@ -2821,7 +2828,7 @@ process_ACK:
* control related information. This typically means increasing
* the congestion window.
*/
cc_ack_received(tp, th, CC_ACK);
cc_ack_received(tp, th, nsegs, CC_ACK);
SOCKBUF_LOCK(&so->so_snd);
if (acked > sbavail(&so->so_snd)) {

1
sys/netinet/tcp_lro.c
View File

@ -392,6 +392,7 @@ tcp_lro_flush(struct lro_ctrl *lc, struct lro_entry *le)
#endif
}
le->m_head->m_pkthdr.lro_nsegs = le->append_cnt + 1;
(*lc->ifp->if_input)(lc->ifp, le->m_head);
lc->lro_queued += le->append_cnt + 1;
lc->lro_flushed++;

2
sys/netinet/tcp_var.h
View File

@ -784,7 +784,7 @@ void tcp_pulloutofband(struct socket *,
void tcp_xmit_timer(struct tcpcb *, int);
void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *);
void cc_ack_received(struct tcpcb *tp, struct tcphdr *th,
uint16_t type);
uint16_t nsegs, uint16_t type);
void cc_conn_init(struct tcpcb *tp);
void cc_post_recovery(struct tcpcb *tp, struct tcphdr *th);
void cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type);

1
sys/sys/mbuf.h
View File

@ -174,6 +174,7 @@ struct pkthdr {
#define PH_vt PH_per
#define vt_nrecs sixteen[0]
#define tso_segsz PH_per.sixteen[1]
#define lro_nsegs tso_segsz
#define csum_phsum PH_per.sixteen[2]
#define csum_data PH_per.thirtytwo[1]