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| Current File : //usr/src/sys/netinet/khelp/h_ertt.c |
/*-
* Copyright (c) 2009-2010
* Swinburne University of Technology, Melbourne, Australia
* Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
* Copyright (c) 2010-2011 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed at the Centre for Advanced Internet
* Architectures, Swinburne University of Technology, by David Hayes, made
* possible in part by a grant from the Cisco University Research Program Fund
* at Community Foundation Silicon Valley.
*
* Portions of this software were developed at the Centre for Advanced
* Internet Architectures, Swinburne University of Technology, Melbourne,
* Australia by David Hayes under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/netinet/khelp/h_ertt.c 239550 2012-08-22 01:28:16Z lstewart $");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/hhook.h>
#include <sys/khelp.h>
#include <sys/module_khelp.h>
#include <sys/socket.h>
#include <sys/sockopt.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_var.h>
#include <netinet/khelp/h_ertt.h>
#include <vm/uma.h>
uma_zone_t txseginfo_zone;
/* Smoothing factor for delayed ack guess. */
#define DLYACK_SMOOTH 5
/* Max number of time stamp errors allowed in a session. */
#define MAX_TS_ERR 10
static int ertt_packet_measurement_hook(int hhook_type, int hhook_id,
void *udata, void *ctx_data, void *hdata, struct osd *hosd);
static int ertt_add_tx_segment_info_hook(int hhook_type, int hhook_id,
void *udata, void *ctx_data, void *hdata, struct osd *hosd);
static int ertt_mod_init(void);
static int ertt_mod_destroy(void);
static int ertt_uma_ctor(void *mem, int size, void *arg, int flags);
static void ertt_uma_dtor(void *mem, int size, void *arg);
/*
* Contains information about the sent segment for comparison with the
* corresponding ack.
*/
struct txseginfo {
/* Segment length. */
long len;
/* Segment sequence number. */
tcp_seq seq;
/* Time stamp indicating when the packet was sent. */
uint32_t tx_ts;
/* Last received receiver ts (if the TCP option is used). */
uint32_t rx_ts;
uint32_t flags;
TAILQ_ENTRY (txseginfo) txsegi_lnk;
};
/* Flags for struct txseginfo. */
#define TXSI_TSO 0x01 /* TSO was used for this entry. */
#define TXSI_RTT_MEASURE_START 0x02 /* Start a per RTT measurement. */
#define TXSI_RX_MEASURE_END 0x04 /* Measure the rx rate until this txsi. */
struct helper ertt_helper = {
.mod_init = ertt_mod_init,
.mod_destroy = ertt_mod_destroy,
.h_flags = HELPER_NEEDS_OSD,
.h_classes = HELPER_CLASS_TCP
};
/* Define the helper hook info required by ERTT. */
struct hookinfo ertt_hooks[] = {
{
.hook_type = HHOOK_TYPE_TCP,
.hook_id = HHOOK_TCP_EST_IN,
.hook_udata = NULL,
.hook_func = &ertt_packet_measurement_hook
},
{
.hook_type = HHOOK_TYPE_TCP,
.hook_id = HHOOK_TCP_EST_OUT,
.hook_udata = NULL,
.hook_func = &ertt_add_tx_segment_info_hook
}
};
/* Flags to indicate how marked_packet_rtt should handle this txsi. */
#define MULTI_ACK 0x01 /* More than this txsi is acked. */
#define OLD_TXSI 0x02 /* TXSI is old according to timestamps. */
#define CORRECT_ACK 0X04 /* Acks this TXSI. */
#define FORCED_MEASUREMENT 0X08 /* Force an RTT measurement. */
/*
* This fuction measures the RTT of a particular segment/ack pair, or the next
* closest if this will yield an inaccurate result due to delayed acking or
* other issues.
*/
static void inline
marked_packet_rtt(struct txseginfo *txsi, struct ertt *e_t, struct tcpcb *tp,
uint32_t *pmeasurenext, int *pmeasurenext_len, int *prtt_bytes_adjust,
int mflag)
{
/*
* If we can't measure this one properly due to delayed acking adjust
* byte counters and flag to measure next txsi. Note that since the
* marked packet's transmitted bytes are measured we need to subtract the
* transmitted bytes. Then pretend the next txsi was marked.
*/
if (mflag & (MULTI_ACK|OLD_TXSI)) {
*pmeasurenext = txsi->tx_ts;
*pmeasurenext_len = txsi->len;
*prtt_bytes_adjust += *pmeasurenext_len;
} else {
if (mflag & FORCED_MEASUREMENT) {
e_t->markedpkt_rtt = tcp_ts_getticks() -
*pmeasurenext + 1;
e_t->bytes_tx_in_marked_rtt = e_t->bytes_tx_in_rtt +
*pmeasurenext_len - *prtt_bytes_adjust;
} else {
e_t->markedpkt_rtt = tcp_ts_getticks() -
txsi->tx_ts + 1;
e_t->bytes_tx_in_marked_rtt = e_t->bytes_tx_in_rtt -
*prtt_bytes_adjust;
}
e_t->marked_snd_cwnd = tp->snd_cwnd;
/*
* Reset the ERTT_MEASUREMENT_IN_PROGRESS flag to indicate to
* add_tx_segment_info that a new measurement should be started.
*/
e_t->flags &= ~ERTT_MEASUREMENT_IN_PROGRESS;
/*
* Set ERTT_NEW_MEASUREMENT to tell the congestion control
* algorithm that a new marked RTT measurement has has been made
* and is available for use.
*/
e_t->flags |= ERTT_NEW_MEASUREMENT;
if (tp->t_flags & TF_TSO) {
/* Temporarily disable TSO to aid a new measurment. */
tp->t_flags &= ~TF_TSO;
/* Keep track that we've disabled it. */
e_t->flags |= ERTT_TSO_DISABLED;
}
}
}
/*
* Ertt_packet_measurements uses a small amount of state kept on each packet
* sent to match incoming acknowledgements. This enables more accurate and
* secure round trip time measurements. The resulting measurement is used for
* congestion control algorithms which require a more accurate time.
* Ertt_packet_measurements is called via the helper hook in tcp_input.c
*/
static int
ertt_packet_measurement_hook(int hhook_type, int hhook_id, void *udata,
void *ctx_data, void *hdata, struct osd *hosd)
{
struct ertt *e_t;
struct tcpcb *tp;
struct tcphdr *th;
struct tcpopt *to;
struct tcp_hhook_data *thdp;
struct txseginfo *txsi;
int acked, measurenext_len, multiack, new_sacked_bytes, rtt_bytes_adjust;
uint32_t measurenext, rts;
tcp_seq ack;
KASSERT(ctx_data != NULL, ("%s: ctx_data is NULL!", __func__));
KASSERT(hdata != NULL, ("%s: hdata is NULL!", __func__));
e_t = (struct ertt *)hdata;
thdp = ctx_data;
tp = thdp->tp;
th = thdp->th;
to = thdp->to;
new_sacked_bytes = (tp->sackhint.last_sack_ack != 0);
measurenext = measurenext_len = multiack = rts = rtt_bytes_adjust = 0;
acked = th->th_ack - tp->snd_una;
INP_WLOCK_ASSERT(tp->t_inpcb);
/* Packet has provided new acknowledgements. */
if (acked > 0 || new_sacked_bytes) {
if (acked == 0 && new_sacked_bytes) {
/* Use last sacked data. */
ack = tp->sackhint.last_sack_ack;
} else
ack = th->th_ack;
txsi = TAILQ_FIRST(&e_t->txsegi_q);
while (txsi != NULL) {
rts = 0;
/* Acknowledgement is acking more than this txsi. */
if (SEQ_GT(ack, txsi->seq + txsi->len)) {
if (txsi->flags & TXSI_RTT_MEASURE_START ||
measurenext) {
marked_packet_rtt(txsi, e_t, tp,
&measurenext, &measurenext_len,
&rtt_bytes_adjust, MULTI_ACK);
}
TAILQ_REMOVE(&e_t->txsegi_q, txsi, txsegi_lnk);
uma_zfree(txseginfo_zone, txsi);
txsi = TAILQ_FIRST(&e_t->txsegi_q);
continue;
}
/*
* Guess if delayed acks are being used by the receiver.
*
* XXXDH: A simple heuristic that could be improved
*/
if (!new_sacked_bytes) {
if (acked > tp->t_maxseg) {
e_t->dlyack_rx +=
(e_t->dlyack_rx < DLYACK_SMOOTH) ?
1 : 0;
multiack = 1;
} else if (acked > txsi->len) {
multiack = 1;
e_t->dlyack_rx +=
(e_t->dlyack_rx < DLYACK_SMOOTH) ?
1 : 0;
} else if (acked == tp->t_maxseg ||
acked == txsi->len) {
e_t->dlyack_rx -=
(e_t->dlyack_rx > 0) ? 1 : 0;
}
/* Otherwise leave dlyack_rx the way it was. */
}
/*
* Time stamps are only to help match the txsi with the
* received acknowledgements.
*/
if (e_t->timestamp_errors < MAX_TS_ERR &&
(to->to_flags & TOF_TS) != 0 && to->to_tsecr) {
/*
* Note: All packets sent with the offload will
* have the same time stamp. If we are sending
* on a fast interface and the t_maxseg is much
* smaller than one tick, this will be fine. The
* time stamp would be the same whether we were
* using tso or not. However, if the interface
* is slow, this will cause problems with the
* calculations. If the interface is slow, there
* is not reason to be using tso, and it should
* be turned off.
*/
/*
* If there are too many time stamp errors, time
* stamps won't be trusted
*/
rts = to->to_tsecr;
/* Before this packet. */
if (!e_t->dlyack_rx && TSTMP_LT(rts, txsi->tx_ts))
/* When delayed acking is used, the
* reflected time stamp is of the first
* packet and thus may be before
* txsi->tx_ts.
*/
break;
if (TSTMP_GT(rts, txsi->tx_ts)) {
/*
* If reflected time stamp is later than
* tx_tsi, then this txsi is old.
*/
if (txsi->flags & TXSI_RTT_MEASURE_START
|| measurenext) {
marked_packet_rtt(txsi, e_t, tp,
&measurenext, &measurenext_len,
&rtt_bytes_adjust, OLD_TXSI);
}
TAILQ_REMOVE(&e_t->txsegi_q, txsi,
txsegi_lnk);
uma_zfree(txseginfo_zone, txsi);
txsi = TAILQ_FIRST(&e_t->txsegi_q);
continue;
}
if (rts == txsi->tx_ts &&
TSTMP_LT(to->to_tsval, txsi->rx_ts)) {
/*
* Segment received before sent!
* Something is wrong with the received
* timestamps so increment errors. If
* this keeps up we will ignore
* timestamps.
*/
e_t->timestamp_errors++;
}
}
/*
* Acknowledging a sequence number before this txsi.
* If it is an old txsi that may have had the same seq
* numbers, it should have been removed if time stamps
* are being used.
*/
if (SEQ_LEQ(ack, txsi->seq))
break; /* Before first packet in txsi. */
/*
* Only ack > txsi->seq and ack <= txsi->seq+txsi->len
* past this point.
*
* If delayed acks are being used, an acknowledgement
* for a single segment will have been delayed by the
* receiver and will yield an inaccurate measurement. In
* this case, we only make the measurement if more than
* one segment is being acknowledged or sack is
* currently being used.
*/
if (!e_t->dlyack_rx || multiack || new_sacked_bytes) {
/* Make an accurate new measurement. */
e_t->rtt = tcp_ts_getticks() - txsi->tx_ts + 1;
if (e_t->rtt < e_t->minrtt || e_t->minrtt == 0)
e_t->minrtt = e_t->rtt;
if (e_t->rtt > e_t->maxrtt || e_t->maxrtt == 0)
e_t->maxrtt = e_t->rtt;
}
if (txsi->flags & TXSI_RTT_MEASURE_START || measurenext)
marked_packet_rtt(txsi, e_t, tp,
&measurenext, &measurenext_len,
&rtt_bytes_adjust, CORRECT_ACK);
if (txsi->flags & TXSI_TSO) {
txsi->len -= acked;
if (txsi->len > 0) {
/*
* This presumes ack for first bytes in
* txsi, this may not be true but it
* shouldn't cause problems for the
* timing.
*
* We remeasure RTT even though we only
* have a single txsi. The rationale
* behind this is that it is better to
* have a slightly inaccurate
* measurement than no additional
* measurement for the rest of the bulk
* transfer. Since TSO is only used on
* high speed interface cards, so the
* packets should be transmitted at line
* rate back to back with little
* difference in transmission times (in
* ticks).
*/
txsi->seq += acked;
/*
* Reset txsi measure flag so we don't
* use it for another RTT measurement.
*/
txsi->flags &= ~TXSI_RTT_MEASURE_START;
/*
* There is still more data to be acked
* from tso bulk transmission, so we
* won't remove it from the TAILQ yet.
*/
break;
}
}
TAILQ_REMOVE(&e_t->txsegi_q, txsi, txsegi_lnk);
uma_zfree(txseginfo_zone, txsi);
break;
}
if (measurenext) {
/*
* We need to do a RTT measurement. It won't be the best
* if we do it here.
*/
marked_packet_rtt(txsi, e_t, tp,
&measurenext, &measurenext_len,
&rtt_bytes_adjust, FORCED_MEASUREMENT);
}
}
return (0);
}
/*
* Add information about a transmitted segment to a list.
* This is called via the helper hook in tcp_output.c
*/
static int
ertt_add_tx_segment_info_hook(int hhook_type, int hhook_id, void *udata,
void *ctx_data, void *hdata, struct osd *hosd)
{
struct ertt *e_t;
struct tcpcb *tp;
struct tcphdr *th;
struct tcpopt *to;
struct tcp_hhook_data *thdp;
struct txseginfo *txsi;
long len;
int tso;
KASSERT(ctx_data != NULL, ("%s: ctx_data is NULL!", __func__));
KASSERT(hdata != NULL, ("%s: hdata is NULL!", __func__));
e_t = (struct ertt *)hdata;
thdp = ctx_data;
tp = thdp->tp;
th = thdp->th;
to = thdp->to;
len = thdp->len;
tso = thdp->tso;
INP_WLOCK_ASSERT(tp->t_inpcb);
if (len > 0) {
txsi = uma_zalloc(txseginfo_zone, M_NOWAIT);
if (txsi != NULL) {
/* Construct txsi setting the necessary flags. */
txsi->flags = 0; /* Needs to be initialised. */
txsi->seq = ntohl(th->th_seq);
txsi->len = len;
if (tso)
txsi->flags |= TXSI_TSO;
else if (e_t->flags & ERTT_TSO_DISABLED) {
tp->t_flags |= TF_TSO;
e_t->flags &= ~ERTT_TSO_DISABLED;
}
if (e_t->flags & ERTT_MEASUREMENT_IN_PROGRESS) {
e_t->bytes_tx_in_rtt += len;
} else {
txsi->flags |= TXSI_RTT_MEASURE_START;
e_t->flags |= ERTT_MEASUREMENT_IN_PROGRESS;
e_t->bytes_tx_in_rtt = len;
}
if (((tp->t_flags & TF_NOOPT) == 0) &&
(to->to_flags & TOF_TS)) {
txsi->tx_ts = ntohl(to->to_tsval) -
tp->ts_offset;
txsi->rx_ts = ntohl(to->to_tsecr);
} else {
txsi->tx_ts = tcp_ts_getticks();
txsi->rx_ts = 0; /* No received time stamp. */
}
TAILQ_INSERT_TAIL(&e_t->txsegi_q, txsi, txsegi_lnk);
}
}
return (0);
}
static int
ertt_mod_init(void)
{
txseginfo_zone = uma_zcreate("ertt_txseginfo", sizeof(struct txseginfo),
NULL, NULL, NULL, NULL, 0, 0);
return (0);
}
static int
ertt_mod_destroy(void)
{
uma_zdestroy(txseginfo_zone);
return (0);
}
static int
ertt_uma_ctor(void *mem, int size, void *arg, int flags)
{
struct ertt *e_t;
e_t = mem;
TAILQ_INIT(&e_t->txsegi_q);
e_t->timestamp_errors = 0;
e_t->minrtt = 0;
e_t->maxrtt = 0;
e_t->rtt = 0;
e_t->flags = 0;
e_t->dlyack_rx = 0;
e_t->bytes_tx_in_rtt = 0;
e_t->markedpkt_rtt = 0;
return (0);
}
static void
ertt_uma_dtor(void *mem, int size, void *arg)
{
struct ertt *e_t;
struct txseginfo *n_txsi, *txsi;
e_t = mem;
txsi = TAILQ_FIRST(&e_t->txsegi_q);
while (txsi != NULL) {
n_txsi = TAILQ_NEXT(txsi, txsegi_lnk);
uma_zfree(txseginfo_zone, txsi);
txsi = n_txsi;
}
}
KHELP_DECLARE_MOD_UMA(ertt, &ertt_helper, ertt_hooks, 1, sizeof(struct ertt),
ertt_uma_ctor, ertt_uma_dtor);