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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /net/ipv4/tcp_vegas.c
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Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ...
Diffstat (limited to '')
-rw-r--r--net/ipv4/tcp_vegas.c340
1 files changed, 340 insertions, 0 deletions
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
new file mode 100644
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+++ b/net/ipv4/tcp_vegas.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TCP Vegas congestion control
+ *
+ * This is based on the congestion detection/avoidance scheme described in
+ * Lawrence S. Brakmo and Larry L. Peterson.
+ * "TCP Vegas: End to end congestion avoidance on a global internet."
+ * IEEE Journal on Selected Areas in Communication, 13(8):1465--1480,
+ * October 1995. Available from:
+ * ftp://ftp.cs.arizona.edu/xkernel/Papers/jsac.ps
+ *
+ * See http://www.cs.arizona.edu/xkernel/ for their implementation.
+ * The main aspects that distinguish this implementation from the
+ * Arizona Vegas implementation are:
+ * o We do not change the loss detection or recovery mechanisms of
+ * Linux in any way. Linux already recovers from losses quite well,
+ * using fine-grained timers, NewReno, and FACK.
+ * o To avoid the performance penalty imposed by increasing cwnd
+ * only every-other RTT during slow start, we increase during
+ * every RTT during slow start, just like Reno.
+ * o Largely to allow continuous cwnd growth during slow start,
+ * we use the rate at which ACKs come back as the "actual"
+ * rate, rather than the rate at which data is sent.
+ * o To speed convergence to the right rate, we set the cwnd
+ * to achieve the right ("actual") rate when we exit slow start.
+ * o To filter out the noise caused by delayed ACKs, we use the
+ * minimum RTT sample observed during the last RTT to calculate
+ * the actual rate.
+ * o When the sender re-starts from idle, it waits until it has
+ * received ACKs for an entire flight of new data before making
+ * a cwnd adjustment decision. The original Vegas implementation
+ * assumed senders never went idle.
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/inet_diag.h>
+
+#include <net/tcp.h>
+
+#include "tcp_vegas.h"
+
+static int alpha = 2;
+static int beta = 4;
+static int gamma = 1;
+
+module_param(alpha, int, 0644);
+MODULE_PARM_DESC(alpha, "lower bound of packets in network");
+module_param(beta, int, 0644);
+MODULE_PARM_DESC(beta, "upper bound of packets in network");
+module_param(gamma, int, 0644);
+MODULE_PARM_DESC(gamma, "limit on increase (scale by 2)");
+
+/* There are several situations when we must "re-start" Vegas:
+ *
+ * o when a connection is established
+ * o after an RTO
+ * o after fast recovery
+ * o when we send a packet and there is no outstanding
+ * unacknowledged data (restarting an idle connection)
+ *
+ * In these circumstances we cannot do a Vegas calculation at the
+ * end of the first RTT, because any calculation we do is using
+ * stale info -- both the saved cwnd and congestion feedback are
+ * stale.
+ *
+ * Instead we must wait until the completion of an RTT during
+ * which we actually receive ACKs.
+ */
+static void vegas_enable(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ /* Begin taking Vegas samples next time we send something. */
+ vegas->doing_vegas_now = 1;
+
+ /* Set the beginning of the next send window. */
+ vegas->beg_snd_nxt = tp->snd_nxt;
+
+ vegas->cntRTT = 0;
+ vegas->minRTT = 0x7fffffff;
+}
+
+/* Stop taking Vegas samples for now. */
+static inline void vegas_disable(struct sock *sk)
+{
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ vegas->doing_vegas_now = 0;
+}
+
+void tcp_vegas_init(struct sock *sk)
+{
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ vegas->baseRTT = 0x7fffffff;
+ vegas_enable(sk);
+}
+EXPORT_SYMBOL_GPL(tcp_vegas_init);
+
+/* Do RTT sampling needed for Vegas.
+ * Basically we:
+ * o min-filter RTT samples from within an RTT to get the current
+ * propagation delay + queuing delay (we are min-filtering to try to
+ * avoid the effects of delayed ACKs)
+ * o min-filter RTT samples from a much longer window (forever for now)
+ * to find the propagation delay (baseRTT)
+ */
+void tcp_vegas_pkts_acked(struct sock *sk, const struct ack_sample *sample)
+{
+ struct vegas *vegas = inet_csk_ca(sk);
+ u32 vrtt;
+
+ if (sample->rtt_us < 0)
+ return;
+
+ /* Never allow zero rtt or baseRTT */
+ vrtt = sample->rtt_us + 1;
+
+ /* Filter to find propagation delay: */
+ if (vrtt < vegas->baseRTT)
+ vegas->baseRTT = vrtt;
+
+ /* Find the min RTT during the last RTT to find
+ * the current prop. delay + queuing delay:
+ */
+ vegas->minRTT = min(vegas->minRTT, vrtt);
+ vegas->cntRTT++;
+}
+EXPORT_SYMBOL_GPL(tcp_vegas_pkts_acked);
+
+void tcp_vegas_state(struct sock *sk, u8 ca_state)
+{
+ if (ca_state == TCP_CA_Open)
+ vegas_enable(sk);
+ else
+ vegas_disable(sk);
+}
+EXPORT_SYMBOL_GPL(tcp_vegas_state);
+
+/*
+ * If the connection is idle and we are restarting,
+ * then we don't want to do any Vegas calculations
+ * until we get fresh RTT samples. So when we
+ * restart, we reset our Vegas state to a clean
+ * slate. After we get acks for this flight of
+ * packets, _then_ we can make Vegas calculations
+ * again.
+ */
+void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event)
+{
+ if (event == CA_EVENT_CWND_RESTART ||
+ event == CA_EVENT_TX_START)
+ tcp_vegas_init(sk);
+}
+EXPORT_SYMBOL_GPL(tcp_vegas_cwnd_event);
+
+static inline u32 tcp_vegas_ssthresh(struct tcp_sock *tp)
+{
+ return min(tp->snd_ssthresh, tcp_snd_cwnd(tp));
+}
+
+static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 acked)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ if (!vegas->doing_vegas_now) {
+ tcp_reno_cong_avoid(sk, ack, acked);
+ return;
+ }
+
+ if (after(ack, vegas->beg_snd_nxt)) {
+ /* Do the Vegas once-per-RTT cwnd adjustment. */
+
+ /* Save the extent of the current window so we can use this
+ * at the end of the next RTT.
+ */
+ vegas->beg_snd_nxt = tp->snd_nxt;
+
+ /* We do the Vegas calculations only if we got enough RTT
+ * samples that we can be reasonably sure that we got
+ * at least one RTT sample that wasn't from a delayed ACK.
+ * If we only had 2 samples total,
+ * then that means we're getting only 1 ACK per RTT, which
+ * means they're almost certainly delayed ACKs.
+ * If we have 3 samples, we should be OK.
+ */
+
+ if (vegas->cntRTT <= 2) {
+ /* We don't have enough RTT samples to do the Vegas
+ * calculation, so we'll behave like Reno.
+ */
+ tcp_reno_cong_avoid(sk, ack, acked);
+ } else {
+ u32 rtt, diff;
+ u64 target_cwnd;
+
+ /* We have enough RTT samples, so, using the Vegas
+ * algorithm, we determine if we should increase or
+ * decrease cwnd, and by how much.
+ */
+
+ /* Pluck out the RTT we are using for the Vegas
+ * calculations. This is the min RTT seen during the
+ * last RTT. Taking the min filters out the effects
+ * of delayed ACKs, at the cost of noticing congestion
+ * a bit later.
+ */
+ rtt = vegas->minRTT;
+
+ /* Calculate the cwnd we should have, if we weren't
+ * going too fast.
+ *
+ * This is:
+ * (actual rate in segments) * baseRTT
+ */
+ target_cwnd = (u64)tcp_snd_cwnd(tp) * vegas->baseRTT;
+ do_div(target_cwnd, rtt);
+
+ /* Calculate the difference between the window we had,
+ * and the window we would like to have. This quantity
+ * is the "Diff" from the Arizona Vegas papers.
+ */
+ diff = tcp_snd_cwnd(tp) * (rtt-vegas->baseRTT) / vegas->baseRTT;
+
+ if (diff > gamma && tcp_in_slow_start(tp)) {
+ /* Going too fast. Time to slow down
+ * and switch to congestion avoidance.
+ */
+
+ /* Set cwnd to match the actual rate
+ * exactly:
+ * cwnd = (actual rate) * baseRTT
+ * Then we add 1 because the integer
+ * truncation robs us of full link
+ * utilization.
+ */
+ tcp_snd_cwnd_set(tp, min(tcp_snd_cwnd(tp),
+ (u32)target_cwnd + 1));
+ tp->snd_ssthresh = tcp_vegas_ssthresh(tp);
+
+ } else if (tcp_in_slow_start(tp)) {
+ /* Slow start. */
+ tcp_slow_start(tp, acked);
+ } else {
+ /* Congestion avoidance. */
+
+ /* Figure out where we would like cwnd
+ * to be.
+ */
+ if (diff > beta) {
+ /* The old window was too fast, so
+ * we slow down.
+ */
+ tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - 1);
+ tp->snd_ssthresh
+ = tcp_vegas_ssthresh(tp);
+ } else if (diff < alpha) {
+ /* We don't have enough extra packets
+ * in the network, so speed up.
+ */
+ tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1);
+ } else {
+ /* Sending just as fast as we
+ * should be.
+ */
+ }
+ }
+
+ if (tcp_snd_cwnd(tp) < 2)
+ tcp_snd_cwnd_set(tp, 2);
+ else if (tcp_snd_cwnd(tp) > tp->snd_cwnd_clamp)
+ tcp_snd_cwnd_set(tp, tp->snd_cwnd_clamp);
+
+ tp->snd_ssthresh = tcp_current_ssthresh(sk);
+ }
+
+ /* Wipe the slate clean for the next RTT. */
+ vegas->cntRTT = 0;
+ vegas->minRTT = 0x7fffffff;
+ }
+ /* Use normal slow start */
+ else if (tcp_in_slow_start(tp))
+ tcp_slow_start(tp, acked);
+}
+
+/* Extract info for Tcp socket info provided via netlink. */
+size_t tcp_vegas_get_info(struct sock *sk, u32 ext, int *attr,
+ union tcp_cc_info *info)
+{
+ const struct vegas *ca = inet_csk_ca(sk);
+
+ if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
+ info->vegas.tcpv_enabled = ca->doing_vegas_now;
+ info->vegas.tcpv_rttcnt = ca->cntRTT;
+ info->vegas.tcpv_rtt = ca->baseRTT;
+ info->vegas.tcpv_minrtt = ca->minRTT;
+
+ *attr = INET_DIAG_VEGASINFO;
+ return sizeof(struct tcpvegas_info);
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tcp_vegas_get_info);
+
+static struct tcp_congestion_ops tcp_vegas __read_mostly = {
+ .init = tcp_vegas_init,
+ .ssthresh = tcp_reno_ssthresh,
+ .undo_cwnd = tcp_reno_undo_cwnd,
+ .cong_avoid = tcp_vegas_cong_avoid,
+ .pkts_acked = tcp_vegas_pkts_acked,
+ .set_state = tcp_vegas_state,
+ .cwnd_event = tcp_vegas_cwnd_event,
+ .get_info = tcp_vegas_get_info,
+
+ .owner = THIS_MODULE,
+ .name = "vegas",
+};
+
+static int __init tcp_vegas_register(void)
+{
+ BUILD_BUG_ON(sizeof(struct vegas) > ICSK_CA_PRIV_SIZE);
+ tcp_register_congestion_control(&tcp_vegas);
+ return 0;
+}
+
+static void __exit tcp_vegas_unregister(void)
+{
+ tcp_unregister_congestion_control(&tcp_vegas);
+}
+
+module_init(tcp_vegas_register);
+module_exit(tcp_vegas_unregister);
+
+MODULE_AUTHOR("Stephen Hemminger");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TCP Vegas");