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linux/net/tipc/bearer.h
Jon Maloy 16ad3f4022 tipc: introduce variable window congestion control 
We introduce a simple variable window congestion control for links.
The algorithm is inspired by the Reno algorithm, covering both 'slow
start', 'congestion avoidance', and 'fast recovery' modes.

- We introduce hard lower and upper window limits per link, still
  different and configurable per bearer type.

- We introduce a 'slow start theshold' variable, initially set to
  the maximum window size.

- We let a link start at the minimum congestion window, i.e. in slow
  start mode, and then let is grow rapidly (+1 per rceived ACK) until
  it reaches the slow start threshold and enters congestion avoidance
  mode.

- In congestion avoidance mode we increment the congestion window for
  each window-size number of acked packets, up to a possible maximum
  equal to the configured maximum window.

- For each non-duplicate NACK received, we drop back to fast recovery
  mode, by setting the both the slow start threshold to and the
  congestion window to (current_congestion_window / 2).

- If the timeout handler finds that the transmit queue has not moved
  since the previous timeout, it drops the link back to slow start
  and forces a probe containing the last sent sequence number to the
  sent to the peer, so that this can discover the stale situation.

This change does in reality have effect only on unicast ethernet
transport, as we have seen that there is no room whatsoever for
increasing the window max size for the UDP bearer.
For now, we also choose to keep the limits for the broadcast link
unchanged and equal.

This algorithm seems to give a 50-100% throughput improvement for
messages larger than MTU.

Suggested-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-10 17:31:15 -08:00

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/*
* net/tipc/bearer.h: Include file for TIPC bearer code
*
* Copyright (c) 1996-2006, 2013-2016, Ericsson AB
* Copyright (c) 2005, 2010-2011, Wind River Systems
* All rights reserved.
*
* 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.
* 3. Neither the names of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
#ifndef _TIPC_BEARER_H
#define _TIPC_BEARER_H
#include "netlink.h"
#include "core.h"
#include "msg.h"
#include <net/genetlink.h>
#define MAX_MEDIA 3
/* Identifiers associated with TIPC message header media address info
* - address info field is 32 bytes long
* - the field's actual content and length is defined per media
* - remaining unused bytes in the field are set to zero
*/
#define TIPC_MEDIA_INFO_SIZE 32
#define TIPC_MEDIA_TYPE_OFFSET 3
#define TIPC_MEDIA_ADDR_OFFSET 4
/*
* Identifiers of supported TIPC media types
*/
#define TIPC_MEDIA_TYPE_ETH 1
#define TIPC_MEDIA_TYPE_IB 2
#define TIPC_MEDIA_TYPE_UDP 3
/* Minimum bearer MTU */
#define TIPC_MIN_BEARER_MTU (MAX_H_SIZE + INT_H_SIZE)
/* Identifiers for distinguishing between broadcast/multicast and replicast
*/
#define TIPC_BROADCAST_SUPPORT 1
#define TIPC_REPLICAST_SUPPORT 2
/**
* struct tipc_media_addr - destination address used by TIPC bearers
* @value: address info (format defined by media)
* @media_id: TIPC media type identifier
* @broadcast: non-zero if address is a broadcast address
*/
struct tipc_media_addr {
u8 value[TIPC_MEDIA_INFO_SIZE];
u8 media_id;
u8 broadcast;
};
struct tipc_bearer;
/**
* struct tipc_media - Media specific info exposed to generic bearer layer
* @send_msg: routine which handles buffer transmission
* @enable_media: routine which enables a media
* @disable_media: routine which disables a media
* @addr2str: convert media address format to string
* @addr2msg: convert from media addr format to discovery msg addr format
* @msg2addr: convert from discovery msg addr format to media addr format
* @raw2addr: convert from raw addr format to media addr format
* @priority: default link (and bearer) priority
* @tolerance: default time (in ms) before declaring link failure
* @window: default window (in packets) before declaring link congestion
* @mtu: max packet size bearer can support for media type not dependent on
* underlying device MTU
* @type_id: TIPC media identifier
* @hwaddr_len: TIPC media address len
* @name: media name
*/
struct tipc_media {
int (*send_msg)(struct net *net, struct sk_buff *buf,
struct tipc_bearer *b,
struct tipc_media_addr *dest);
int (*enable_media)(struct net *net, struct tipc_bearer *b,
struct nlattr *attr[]);
void (*disable_media)(struct tipc_bearer *b);
int (*addr2str)(struct tipc_media_addr *addr,
char *strbuf,
int bufsz);
int (*addr2msg)(char *msg, struct tipc_media_addr *addr);
int (*msg2addr)(struct tipc_bearer *b,
struct tipc_media_addr *addr,
char *msg);
int (*raw2addr)(struct tipc_bearer *b,
struct tipc_media_addr *addr,
char *raw);
u32 priority;
u32 tolerance;
u32 min_win;
u32 max_win;
u32 mtu;
u32 type_id;
u32 hwaddr_len;
char name[TIPC_MAX_MEDIA_NAME];
};
/**
* struct tipc_bearer - Generic TIPC bearer structure
* @media_ptr: pointer to additional media-specific information about bearer
* @mtu: max packet size bearer can support
* @addr: media-specific address associated with bearer
* @name: bearer name (format = media:interface)
* @media: ptr to media structure associated with bearer
* @bcast_addr: media address used in broadcasting
* @pt: packet type for bearer
* @rcu: rcu struct for tipc_bearer
* @priority: default link priority for bearer
* @window: default window size for bearer
* @tolerance: default link tolerance for bearer
* @domain: network domain to which links can be established
* @identity: array index of this bearer within TIPC bearer array
* @link_req: ptr to (optional) structure making periodic link setup requests
* @net_plane: network plane ('A' through 'H') currently associated with bearer
*
* Note: media-specific code is responsible for initialization of the fields
* indicated below when a bearer is enabled; TIPC's generic bearer code takes
* care of initializing all other fields.
*/
struct tipc_bearer {
void __rcu *media_ptr; /* initalized by media */
u32 mtu; /* initalized by media */
struct tipc_media_addr addr; /* initalized by media */
char name[TIPC_MAX_BEARER_NAME];
struct tipc_media *media;
struct tipc_media_addr bcast_addr;
struct packet_type pt;
struct rcu_head rcu;
u32 priority;
u32 min_win;
u32 max_win;
u32 tolerance;
u32 domain;
u32 identity;
struct tipc_discoverer *disc;
char net_plane;
unsigned long up;
refcount_t refcnt;
};
struct tipc_bearer_names {
char media_name[TIPC_MAX_MEDIA_NAME];
char if_name[TIPC_MAX_IF_NAME];
};
/*
* TIPC routines available to supported media types
*/
void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b);
/*
* Routines made available to TIPC by supported media types
*/
extern struct tipc_media eth_media_info;
#ifdef CONFIG_TIPC_MEDIA_IB
extern struct tipc_media ib_media_info;
#endif
#ifdef CONFIG_TIPC_MEDIA_UDP
extern struct tipc_media udp_media_info;
#endif
int tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info);
int __tipc_nl_bearer_disable(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info);
int __tipc_nl_bearer_enable(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_bearer_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info);
int __tipc_nl_bearer_set(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_bearer_add(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_media_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_media_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info);
int __tipc_nl_media_set(struct sk_buff *skb, struct genl_info *info);
int tipc_media_set_priority(const char *name, u32 new_value);
int tipc_media_set_window(const char *name, u32 new_value);
int tipc_media_addr_printf(char *buf, int len, struct tipc_media_addr *a);
int tipc_enable_l2_media(struct net *net, struct tipc_bearer *b,
struct nlattr *attrs[]);
bool tipc_bearer_hold(struct tipc_bearer *b);
void tipc_bearer_put(struct tipc_bearer *b);
void tipc_disable_l2_media(struct tipc_bearer *b);
int tipc_l2_send_msg(struct net *net, struct sk_buff *buf,
struct tipc_bearer *b, struct tipc_media_addr *dest);
void tipc_bearer_add_dest(struct net *net, u32 bearer_id, u32 dest);
void tipc_bearer_remove_dest(struct net *net, u32 bearer_id, u32 dest);
struct tipc_bearer *tipc_bearer_find(struct net *net, const char *name);
int tipc_bearer_get_name(struct net *net, char *name, u32 bearer_id);
struct tipc_media *tipc_media_find(const char *name);
int tipc_bearer_setup(void);
void tipc_bearer_cleanup(void);
void tipc_bearer_stop(struct net *net);
int tipc_bearer_mtu(struct net *net, u32 bearer_id);
bool tipc_bearer_bcast_support(struct net *net, u32 bearer_id);
void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id,
struct sk_buff *skb,
struct tipc_media_addr *dest);
void tipc_bearer_xmit(struct net *net, u32 bearer_id,
struct sk_buff_head *xmitq,
struct tipc_media_addr *dst,
struct tipc_node *__dnode);
void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id,
struct sk_buff_head *xmitq);
void tipc_clone_to_loopback(struct net *net, struct sk_buff_head *pkts);
int tipc_attach_loopback(struct net *net);
void tipc_detach_loopback(struct net *net);
static inline void tipc_loopback_trace(struct net *net,
struct sk_buff_head *pkts)
{
if (unlikely(dev_nit_active(net->loopback_dev)))
tipc_clone_to_loopback(net, pkts);
}
/* check if device MTU is too low for tipc headers */
static inline bool tipc_mtu_bad(struct net_device *dev, unsigned int reserve)
{
if (dev->mtu >= TIPC_MIN_BEARER_MTU + reserve)
return false;
netdev_warn(dev, "MTU too low for tipc bearer\n");
return true;
}
#endif /* _TIPC_BEARER_H */
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