linux-toradex.git/net/ipv4/tcp_timer.c, branch v4.7-rc2 Linux kernel for Apalis and Colibri modules tcp: do not assume TCP code is non preemptible 2016-05-02T21:02:25+00:00 Eric Dumazet edumazet@google.com 2016-04-29T21:16:47+00:00 c10d9310edf5aa4a676991139d1a43ec7d87e56b We want to to make TCP stack preemptible, as draining prequeue and backlog queues can take lot of time. Many SNMP updates were assuming that BH (and preemption) was disabled. Need to convert some __NET_INC_STATS() calls to NET_INC_STATS() and some __TCP_INC_STATS() to TCP_INC_STATS() Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset() and tcp_v4_send_ack(), we add an explicit preempt disabled section. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
We want to to make TCP stack preemptible, as draining prequeue
and backlog queues can take lot of time.

Many SNMP updates were assuming that BH (and preemption) was disabled.

Need to convert some __NET_INC_STATS() calls to NET_INC_STATS()
and some __TCP_INC_STATS() to TCP_INC_STATS()

Before using this_cpu_ptr(net->ipv4.tcp_sk) in tcp_v4_send_reset()
and tcp_v4_send_ack(), we add an explicit preempt disabled section.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: rename NET_{ADD|INC}_STATS_BH() 2016-04-28T02:48:24+00:00 Eric Dumazet edumazet@google.com 2016-04-27T23:44:39+00:00 02a1d6e7a6bb025a77da77012190e1efc1970f1c Rename NET_INC_STATS_BH() to __NET_INC_STATS() and NET_ADD_STATS_BH() to __NET_ADD_STATS() Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Rename NET_INC_STATS_BH() to __NET_INC_STATS()
and NET_ADD_STATS_BH() to __NET_ADD_STATS()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp-tso: do not split TSO packets at retransmit time 2016-04-24T18:43:59+00:00 Eric Dumazet edumazet@google.com 2016-04-21T17:55:23+00:00 10d3be569243def8d92ac3722395ef5a59c504e6 Linux TCP stack painfully segments all TSO/GSO packets before retransmits. This was fine back in the days when TSO/GSO were emerging, with their bugs, but we believe the dark age is over. Keeping big packets in write queues, but also in stack traversal has a lot of benefits. - Less memory overhead, because write queues have less skbs - Less cpu overhead at ACK processing. - Better SACK processing, as lot of studies mentioned how awful linux was at this ;) - Less cpu overhead to send the rtx packets (IP stack traversal, netfilter traversal, drivers...) - Better latencies in presence of losses. - Smaller spikes in fq like packet schedulers, as retransmits are not constrained by TCP Small Queues. 1 % packet losses are common today, and at 100Gbit speeds, this translates to ~80,000 losses per second. Losses are often correlated, and we see many retransmit events leading to 1-MSS train of packets, at the time hosts are already under stress. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Linux TCP stack painfully segments all TSO/GSO packets before retransmits.

This was fine back in the days when TSO/GSO were emerging, with their
bugs, but we believe the dark age is over.

Keeping big packets in write queues, but also in stack traversal
has a lot of benefits.
 - Less memory overhead, because write queues have less skbs
 - Less cpu overhead at ACK processing.
 - Better SACK processing, as lot of studies mentioned how
   awful linux was at this ;)
 - Less cpu overhead to send the rtx packets
   (IP stack traversal, netfilter traversal, drivers...)
 - Better latencies in presence of losses.
 - Smaller spikes in fq like packet schedulers, as retransmits
   are not constrained by TCP Small Queues.

1 % packet losses are common today, and at 100Gbit speeds, this
translates to ~80,000 losses per second.
Losses are often correlated, and we see many retransmit events
leading to 1-MSS train of packets, at the time hosts are already
under stress.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp_orphan_retries sysctl knob 2016-02-07T19:35:11+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:55+00:00 c402d9beffb6141ab2e4d2ad8be71128803a28ca Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp_retries2 sysctl knob 2016-02-07T19:35:11+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:54+00:00 c6214a97c86c660de4f7ddb8eed925192e646161 Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp_retries1 sysctl knob 2016-02-07T19:35:10+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:53+00:00 ae5c3f406cffe15ffd2aa544961b7cd027468d46 Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp synack retries sysctl knob 2016-02-07T19:35:10+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:50+00:00 7c083ecb3ba4583a625d5ff9655d1a819e374493 Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespaceify tcp syn retries sysctl knob 2016-02-07T19:35:10+00:00 Nikolay Borisov kernel@kyup.com 2016-02-03T07:46:49+00:00 6fa251663069e05daadd1666cbf3b658bf840ea4 Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespecify the tcp_keepalive_intvl sysctl knob 2016-01-10T22:32:09+00:00 Nikolay Borisov kernel@kyup.com 2016-01-07T14:38:45+00:00 b840d15d39128d08ed4486085e5507d2617b9ae1 This is the final part required to namespaceify the tcp keep alive mechanism. Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This is the final part required to namespaceify the tcp
keep alive mechanism.

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: Namespecify tcp_keepalive_probes sysctl knob 2016-01-10T22:32:09+00:00 Nikolay Borisov kernel@kyup.com 2016-01-07T14:38:44+00:00 9bd6861bd4326e3afd3f14a9ec8a723771fb20bb This is required to have full tcp keepalive mechanism namespace support. Signed-off-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
This is required to have full tcp keepalive mechanism namespace
support.

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David S. Miller <davem@davemloft.net>