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linux/net/ipv4
Nandita Dukkipati a262f0cdf1 Proportional Rate Reduction for TCP.
This patch implements Proportional Rate Reduction (PRR) for TCP.
PRR is an algorithm that determines TCP's sending rate in fast
recovery. PRR avoids excessive window reductions and aims for
the actual congestion window size at the end of recovery to be as
close as possible to the window determined by the congestion control
algorithm. PRR also improves accuracy of the amount of data sent
during loss recovery.

The patch implements the recommended flavor of PRR called PRR-SSRB
(Proportional rate reduction with slow start reduction bound) and
replaces the existing rate halving algorithm. PRR improves upon the
existing Linux fast recovery under a number of conditions including:
  1) burst losses where the losses implicitly reduce the amount of
outstanding data (pipe) below the ssthresh value selected by the
congestion control algorithm and,
  2) losses near the end of short flows where application runs out of
data to send.

As an example, with the existing rate halving implementation a single
loss event can cause a connection carrying short Web transactions to
go into the slow start mode after the recovery. This is because during
recovery Linux pulls the congestion window down to packets_in_flight+1
on every ACK. A short Web response often runs out of new data to send
and its pipe reduces to zero by the end of recovery when all its packets
are drained from the network. Subsequent HTTP responses using the same
connection will have to slow start to raise cwnd to ssthresh. PRR on
the other hand aims for the cwnd to be as close as possible to ssthresh
by the end of recovery.

A description of PRR and a discussion of its performance can be found at
the following links:
- IETF Draft:
    http://tools.ietf.org/html/draft-mathis-tcpm-proportional-rate-reduction-01
- IETF Slides:
    http://www.ietf.org/proceedings/80/slides/tcpm-6.pdf
    http://tools.ietf.org/agenda/81/slides/tcpm-2.pdf
- Paper to appear in Internet Measurements Conference (IMC) 2011:
    Improving TCP Loss Recovery
    Nandita Dukkipati, Matt Mathis, Yuchung Cheng

Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-08-24 19:40:40 -07:00
..
netfilter Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net 2011-08-07 23:20:26 -07:00
af_inet.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-07-05 23:23:37 -07:00
ah4.c inet: constify ip headers and in6_addr 2011-04-22 11:04:14 -07:00
arp.c neigh: Pass neighbour entry to output ops. 2011-07-17 23:11:17 -07:00
cipso_ipv4.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
datagram.c ipv4: Lock socket and use cork flow in ip4_datagram_connect(). 2011-05-08 13:48:57 -07:00
devinet.c rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER 2011-08-02 04:29:23 -07:00
esp4.c inet: constify ip headers and in6_addr 2011-04-22 11:04:14 -07:00
fib_frontend.c rtnetlink: Compute and store minimum ifinfo dump size 2011-06-09 20:38:07 -07:00
fib_lookup.h ipv4: Fix nexthop caching wrt. scoping. 2011-03-24 18:06:47 -07:00
fib_rules.c ipv4: Use flowi4 in FIB layer. 2011-03-12 15:08:49 -08:00
fib_semantics.c net,rcu: convert call_rcu(fc_rport_free_rcu) to kfree_rcu() 2011-05-07 22:50:55 -07:00
fib_trie.c rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER 2011-08-02 04:29:23 -07:00
gre.c rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER 2011-08-02 04:29:23 -07:00
icmp.c icmp: Fix regression in nexthop resolution during replies. 2011-07-22 06:22:10 -07:00
igmp.c net: remove ndo_set_multicast_list callback 2011-08-17 20:22:03 -07:00
inet_connection_sock.c seqlock: Get rid of SEQLOCK_UNLOCKED 2011-05-24 15:22:17 +02:00
inet_diag.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2011-06-20 22:29:08 -07:00
inet_fragment.c
inet_hashtables.c net: Compute protocol sequence numbers and fragment IDs using MD5. 2011-08-06 18:33:19 -07:00
inet_lro.c net: ipv4: convert to SKB frag APIs 2011-08-24 17:52:11 -07:00
inet_timewait_sock.c tcp: fix inet_twsk_deschedule() 2011-02-19 18:59:04 -08:00
inetpeer.c net: Compute protocol sequence numbers and fragment IDs using MD5. 2011-08-06 18:33:19 -07:00
ip_forward.c ipv4: Fix 'iph' use before set. 2011-05-12 23:03:46 -04:00
ip_fragment.c ipv4: Add ip_defrag() agent IP_DEFRAG_AF_PACKET. 2011-07-05 22:34:52 -07:00
ip_gre.c net: Abstract dst->neighbour accesses behind helpers. 2011-07-17 23:11:35 -07:00
ip_input.c ip: introduce ip_is_fragment helper inline function 2011-06-21 20:33:34 -07:00
ip_options.c ip_options_compile: properly handle unaligned pointer 2011-05-31 15:11:02 -07:00
ip_output.c net: ipv4: convert to SKB frag APIs 2011-08-24 17:52:11 -07:00
ip_sockglue.c ipv4: Fix ip_getsockopt for IP_PKTOPTIONS 2011-08-07 22:31:07 -07:00
ipcomp.c inet: constify ip headers and in6_addr 2011-04-22 11:04:14 -07:00
ipconfig.c ipconfig: Reduce switch/case indent 2011-07-01 16:11:15 -07:00
ipip.c rcu: convert uses of rcu_assign_pointer(x, NULL) to RCU_INIT_POINTER 2011-08-02 04:29:23 -07:00
ipmr.c net: cleanup some rcu_dereference_raw 2011-08-12 02:55:28 -07:00
Kconfig ipv4: Remove fib_hash. 2011-02-01 15:35:25 -08:00
Makefile net: ipv4: add IPPROTO_ICMP socket kind 2011-05-13 16:08:13 -04:00
netfilter.c netfilter: TCP and raw fix for ip_route_me_harder 2011-08-07 22:52:32 -07:00
ping.c ipv4, ping: Remove duplicate icmp.h include 2011-06-20 13:04:38 -07:00
proc.c tcp: Replace time wait bucket msg by counter 2010-12-08 12:16:33 -08:00
protocol.c
raw.c ipv4: route non-local sources for raw socket 2011-08-07 22:52:32 -07:00
route.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net 2011-08-20 10:39:12 -07:00
syncookies.c tcp: initialize variable ecn_ok in syncookies path 2011-08-10 21:59:57 -07:00
sysctl_net_ipv4.c inetpeer: remove unused list 2011-06-08 17:05:30 -07:00
tcp_bic.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_cong.c
tcp_cubic.c tcp_cubic: limit delayed_ack ratio to prevent divide error 2011-05-08 15:51:57 -07:00
tcp_diag.c
tcp_highspeed.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_htcp.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_hybla.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_illinois.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_input.c Proportional Rate Reduction for TCP. 2011-08-24 19:40:40 -07:00
tcp_ipv4.c rps: Add flag to skb to indicate rxhash is based on L4 tuple 2011-08-17 20:06:03 -07:00
tcp_lp.c Fix common misspellings 2011-03-31 11:26:23 -03:00
tcp_minisocks.c tcp: RFC2988bis + taking RTT sample from 3WHS for the passive open side 2011-06-08 17:05:30 -07:00
tcp_output.c Proportional Rate Reduction for TCP. 2011-08-24 19:40:40 -07:00
tcp_probe.c net: ipv4: tcp_probe: cleanup snprintf() use 2010-11-17 12:27:46 -08:00
tcp_scalable.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_timer.c tcp: Remove debug macro of TCP_CHECK_TIMER 2011-02-20 11:10:14 -08:00
tcp_vegas.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_vegas.h
tcp_veno.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_westwood.c tcp: mark tcp_congestion_ops read_mostly 2011-03-10 00:40:17 -08:00
tcp_yeah.c Fix common misspellings 2011-03-31 11:26:23 -03:00
tcp.c net: ipv4: convert to SKB frag APIs 2011-08-24 17:52:11 -07:00
tunnel4.c
udp_impl.h
udp.c rps: Add flag to skb to indicate rxhash is based on L4 tuple 2011-08-17 20:06:03 -07:00
udplite.c net: fix nulls list corruptions in sk_prot_alloc 2010-12-16 14:26:56 -08:00
xfrm4_input.c
xfrm4_mode_beet.c
xfrm4_mode_transport.c
xfrm4_mode_tunnel.c ipv4: Don't pre-seed hoplimit metric. 2010-12-12 22:08:17 -08:00
xfrm4_output.c xfrm4: Don't call icmp_send on local error 2011-07-01 17:33:19 -07:00
xfrm4_policy.c ip: introduce ip_is_fragment helper inline function 2011-06-21 20:33:34 -07:00
xfrm4_state.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-3.6 2011-05-11 14:26:58 -04:00
xfrm4_tunnel.c