svn commit: r218152 - in head/sys: modules/cc modules/cc/cc_vegas
netinet/cc
Lawrence Stewart
lstewart at FreeBSD.org
Tue Feb 1 06:17:01 UTC 2011
Author: lstewart
Date: Tue Feb 1 06:17:00 2011
New Revision: 218152
URL: http://svn.freebsd.org/changeset/base/218152
Log:
Import a clean-room implementation of the VEGAS congestion control algorithm
based on the paper "TCP Vegas: end to end congestion avoidance on a global
internet" by Brakmo and Peterson. It is implemented as a kernel module
compatible with the recently committed modular congestion control framework.
VEGAS uses network delay as a congestion indicator and unlike regular loss-based
algorithms, attempts to keep the network operating with stable queuing delays
and no congestion losses. By keeping network buffers used along the path within
a set range, queuing delays are kept low while maintaining high throughput.
In collaboration with: David Hayes <dahayes at swin edu au> and
Grenville Armitage <garmitage at swin edu au>
Sponsored by: FreeBSD Foundation
Reviewed by: bz and others along the way
MFC after: 3 months
Added:
head/sys/modules/cc/cc_vegas/
head/sys/modules/cc/cc_vegas/Makefile (contents, props changed)
head/sys/netinet/cc/cc_vegas.c (contents, props changed)
Modified:
head/sys/modules/cc/Makefile
Modified: head/sys/modules/cc/Makefile
==============================================================================
--- head/sys/modules/cc/Makefile Tue Feb 1 04:39:15 2011 (r218151)
+++ head/sys/modules/cc/Makefile Tue Feb 1 06:17:00 2011 (r218152)
@@ -1,6 +1,7 @@
# $FreeBSD$
SUBDIR= cc_cubic \
- cc_htcp
+ cc_htcp \
+ cc_vegas
.include <bsd.subdir.mk>
Added: head/sys/modules/cc/cc_vegas/Makefile
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/modules/cc/cc_vegas/Makefile Tue Feb 1 06:17:00 2011 (r218152)
@@ -0,0 +1,9 @@
+# $FreeBSD$
+
+.include <bsd.own.mk>
+
+.PATH: ${.CURDIR}/../../../netinet/cc
+KMOD= cc_vegas
+SRCS= cc_vegas.c
+
+.include <bsd.kmod.mk>
Added: head/sys/netinet/cc/cc_vegas.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/netinet/cc/cc_vegas.c Tue Feb 1 06:17:00 2011 (r218152)
@@ -0,0 +1,308 @@
+/*-
+ * Copyright (c) 2009-2010
+ * Swinburne University of Technology, Melbourne, Australia
+ * Copyright (c) 2010 Lawrence Stewart <lstewart at 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, by David Hayes and Lawrence Stewart,
+ * 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.
+ */
+
+/*
+ * An implementation of the Vegas congestion control algorithm for FreeBSD,
+ * based on L. S. Brakmo and L. L. Peterson, "TCP Vegas: end to end congestion
+ * avoidance on a global internet", IEEE J. Sel. Areas Commun., vol. 13, no. 8,
+ * pp. 1465-1480, Oct. 1995. The original Vegas duplicate ack policy has not
+ * been implemented, since clock ticks are not as course as they were (i.e.
+ * 500ms) when Vegas was designed. Also, packets are timed once per RTT as in
+ * the original paper.
+ *
+ * Originally released as part of the NewTCP research project at Swinburne
+ * University's Centre for Advanced Internet Architectures, Melbourne,
+ * Australia, which was made possible in part by a grant from the Cisco
+ * University Research Program Fund at Community Foundation Silicon Valley. More
+ * details are available at:
+ * http://caia.swin.edu.au/urp/newtcp/
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/khelp.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
+#include <sys/queue.h>
+#include <sys/socket.h>
+#include <sys/socketvar.h>
+#include <sys/sysctl.h>
+#include <sys/systm.h>
+
+#include <net/if.h>
+#include <net/vnet.h>
+
+#include <netinet/cc.h>
+#include <netinet/tcp_seq.h>
+#include <netinet/tcp_timer.h>
+#include <netinet/tcp_var.h>
+
+#include <netinet/cc/cc_module.h>
+
+#include <netinet/khelp/h_ertt.h>
+
+#define CAST_PTR_INT(X) (*((int*)(X)))
+
+/*
+ * Private signal type for rate based congestion signal.
+ * See <netinet/cc.h> for appropriate bit-range to use for private signals.
+ */
+#define CC_VEGAS_RATE 0x01000000
+
+static void vegas_ack_received(struct cc_var *ccv, uint16_t ack_type);
+static void vegas_cb_destroy(struct cc_var *ccv);
+static int vegas_cb_init(struct cc_var *ccv);
+static void vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type);
+static void vegas_conn_init(struct cc_var *ccv);
+static int vegas_mod_init(void);
+
+struct vegas {
+ int slow_start_toggle;
+};
+
+static int32_t ertt_id;
+
+static VNET_DEFINE(uint32_t, vegas_alpha) = 1;
+static VNET_DEFINE(uint32_t, vegas_beta) = 3;
+#define V_vegas_alpha VNET(vegas_alpha)
+#define V_vegas_beta VNET(vegas_beta)
+
+MALLOC_DECLARE(M_VEGAS);
+MALLOC_DEFINE(M_VEGAS, "vegas data",
+ "Per connection data required for the Vegas congestion control algorithm");
+
+struct cc_algo vegas_cc_algo = {
+ .name = "vegas",
+ .ack_received = vegas_ack_received,
+ .cb_destroy = vegas_cb_destroy,
+ .cb_init = vegas_cb_init,
+ .cong_signal = vegas_cong_signal,
+ .conn_init = vegas_conn_init,
+ .mod_init = vegas_mod_init
+};
+
+/*
+ * The vegas window adjustment is done once every RTT, as indicated by the
+ * ERTT_NEW_MEASUREMENT flag. This flag is reset once the new measurment data
+ * has been used.
+ */
+static void
+vegas_ack_received(struct cc_var *ccv, uint16_t ack_type)
+{
+ struct ertt *e_t;
+ struct vegas *vegas_data;
+ long actual_tx_rate, expected_tx_rate, ndiff;
+
+ e_t = khelp_get_osd(CCV(ccv, osd), ertt_id);
+ vegas_data = ccv->cc_data;
+
+ if (e_t->flags & ERTT_NEW_MEASUREMENT) { /* Once per RTT. */
+ if (e_t->minrtt && e_t->markedpkt_rtt) {
+ expected_tx_rate = e_t->marked_snd_cwnd / e_t->minrtt;
+ actual_tx_rate = e_t->bytes_tx_in_marked_rtt /
+ e_t->markedpkt_rtt;
+ ndiff = (expected_tx_rate - actual_tx_rate) *
+ e_t->minrtt / CCV(ccv, t_maxseg);
+
+ if (ndiff < V_vegas_alpha) {
+ if (CCV(ccv, snd_cwnd) <=
+ CCV(ccv, snd_ssthresh)) {
+ vegas_data->slow_start_toggle =
+ vegas_data->slow_start_toggle ?
+ 0 : 1;
+ } else {
+ vegas_data->slow_start_toggle = 0;
+ CCV(ccv, snd_cwnd) =
+ min(CCV(ccv, snd_cwnd) +
+ CCV(ccv, t_maxseg),
+ TCP_MAXWIN << CCV(ccv, snd_scale));
+ }
+ } else if (ndiff > V_vegas_beta) {
+ /* Rate-based congestion. */
+ vegas_cong_signal(ccv, CC_VEGAS_RATE);
+ vegas_data->slow_start_toggle = 0;
+ }
+ }
+ e_t->flags &= ~ERTT_NEW_MEASUREMENT;
+ }
+
+ if (vegas_data->slow_start_toggle)
+ newreno_cc_algo.ack_received(ccv, ack_type);
+}
+
+static void
+vegas_cb_destroy(struct cc_var *ccv)
+{
+
+ if (ccv->cc_data != NULL)
+ free(ccv->cc_data, M_VEGAS);
+}
+
+static int
+vegas_cb_init(struct cc_var *ccv)
+{
+ struct vegas *vegas_data;
+
+ vegas_data = malloc(sizeof(struct vegas), M_VEGAS, M_NOWAIT);
+
+ if (vegas_data == NULL)
+ return (ENOMEM);
+
+ vegas_data->slow_start_toggle = 1;
+ ccv->cc_data = vegas_data;
+
+ return (0);
+}
+
+/*
+ * If congestion has been triggered triggered by the Vegas measured rates, it is
+ * handled here, otherwise it falls back to newreno's congestion handling.
+ */
+static void
+vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type)
+{
+ struct vegas *vegas_data;
+ int presignalrecov;
+
+ vegas_data = ccv->cc_data;
+
+ if (IN_RECOVERY(CCV(ccv, t_flags)))
+ presignalrecov = 1;
+ else
+ presignalrecov = 0;
+
+ switch(signal_type) {
+ case CC_VEGAS_RATE:
+ if (!IN_RECOVERY(CCV(ccv, t_flags))) {
+ CCV(ccv, snd_cwnd) = max(2 * CCV(ccv, t_maxseg),
+ CCV(ccv, snd_cwnd) - CCV(ccv, t_maxseg));
+ if (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh))
+ /* Exit slow start. */
+ CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd);
+ }
+ break;
+
+ default:
+ newreno_cc_algo.cong_signal(ccv, signal_type);
+ }
+
+ if (IN_RECOVERY(CCV(ccv, t_flags)) && !presignalrecov)
+ vegas_data->slow_start_toggle =
+ (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh)) ? 1 : 0;
+}
+
+static void
+vegas_conn_init(struct cc_var *ccv)
+{
+ struct vegas *vegas_data;
+
+ vegas_data = ccv->cc_data;
+ vegas_data->slow_start_toggle = 1;
+}
+
+static int
+vegas_mod_init(void)
+{
+
+ ertt_id = khelp_get_id("ertt");
+ if (ertt_id <= 0) {
+ printf("%s: h_ertt module not found\n", __func__);
+ return (ENOENT);
+ }
+
+ vegas_cc_algo.after_idle = newreno_cc_algo.after_idle;
+ vegas_cc_algo.post_recovery = newreno_cc_algo.post_recovery;
+
+ return (0);
+}
+
+static int
+vegas_alpha_handler(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+ uint32_t new;
+
+ new = V_vegas_alpha;
+ error = sysctl_handle_int(oidp, &new, 0, req);
+ if (error == 0 && req->newptr != NULL) {
+ if (CAST_PTR_INT(req->newptr) < 1 ||
+ CAST_PTR_INT(req->newptr) > V_vegas_beta)
+ error = EINVAL;
+ else
+ V_vegas_alpha = new;
+ }
+
+ return (error);
+}
+
+static int
+vegas_beta_handler(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+ uint32_t new;
+
+ new = V_vegas_beta;
+ error = sysctl_handle_int(oidp, &new, 0, req);
+ if (error == 0 && req->newptr != NULL) {
+ if (CAST_PTR_INT(req->newptr) < 1 ||
+ CAST_PTR_INT(req->newptr) < V_vegas_alpha)
+ error = EINVAL;
+ else
+ V_vegas_beta = new;
+ }
+
+ return (error);
+}
+
+SYSCTL_DECL(_net_inet_tcp_cc_vegas);
+SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, vegas, CTLFLAG_RW, NULL,
+ "Vegas related settings");
+
+SYSCTL_VNET_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, alpha,
+ CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(vegas_alpha), 1, &vegas_alpha_handler,
+ "IU", "vegas alpha, specified as number of \"buffers\" (0 < alpha < beta)");
+
+SYSCTL_VNET_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, beta,
+ CTLTYPE_UINT|CTLFLAG_RW, &VNET_NAME(vegas_beta), 3, &vegas_beta_handler,
+ "IU", "vegas beta, specified as number of \"buffers\" (0 < alpha < beta)");
+
+DECLARE_CC_MODULE(vegas, &vegas_cc_algo);
+MODULE_DEPEND(vegas, ertt, 1, 1, 1);
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