linux-stable.git/net/ipv4/proc.c, branch v4.15

tcp: retire FACK loss detection

2017-11-11T09:53:16+00:00

FACK loss detection has been disabled by default and the
successor RACK subsumed FACK and can handle reordering better.
This patch removes FACK to simplify TCP loss recovery.

Signed-off-by: Yuchung Cheng 
Reviewed-by: Eric Dumazet 
Reviewed-by: Neal Cardwell 
Reviewed-by: Soheil Hassas Yeganeh 
Reviewed-by: Priyaranjan Jha 
Signed-off-by: David S. Miller

tcp: Revert "tcp: remove header prediction"

2017-08-30T18:20:09+00:00

This reverts commit 45f119bf936b1f9f546a0b139c5b56f9bb2bdc78.

Eric Dumazet says:
  We found at Google a significant regression caused by
  45f119bf936b1f9f546a0b139c5b56f9bb2bdc78 tcp: remove header prediction

  In typical RPC  (TCP_RR), when a TCP socket receives data, we now call
  tcp_ack() while we used to not call it.

  This touches enough cache lines to cause a slowdown.

so problem does not seem to be HP removal itself but the tcp_ack()
call.  Therefore, it might be possible to remove HP after all, provided
one finds a way to elide tcp_ack for most cases.

Reported-by: Eric Dumazet 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

tcp: remove unused mib counters

2017-07-31T21:37:50+00:00

was used by tcp prequeue and header prediction.
TCPFORWARDRETRANS use was removed in january.

Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

tcp: add TCPMemoryPressuresChrono counter

2017-06-08T15:26:19+00:00

DRAM supply shortage and poor memory pressure tracking in TCP
stack makes any change in SO_SNDBUF/SO_RCVBUF (or equivalent autotuning
limits) and tcp_mem[] quite hazardous.

TCPMemoryPressures SNMP counter is an indication of tcp_mem sysctl
limits being hit, but only tracking number of transitions.

If TCP stack behavior under stress was perfect :
1) It would maintain memory usage close to the limit.
2) Memory pressure state would be entered for short times.

We certainly prefer 100 events lasting 10ms compared to one event
lasting 200 seconds.

This patch adds a new SNMP counter tracking cumulative duration of
memory pressure events, given in ms units.

$ cat /proc/sys/net/ipv4/tcp_mem
3088    4117    6176
$ grep TCP /proc/net/sockstat
TCP: inuse 180 orphan 0 tw 2 alloc 234 mem 4140
$ nstat -n ; sleep 10 ; nstat |grep Pressure
TcpExtTCPMemoryPressures        1700
TcpExtTCPMemoryPressuresChrono  5209

v2: Used EXPORT_SYMBOL_GPL() instead of EXPORT_SYMBOL() as David
instructed.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net/tcp_fastopen: Add snmp counter for blackhole detection

2017-04-24T18:27:17+00:00

This counter records the number of times the firewall blackhole issue is
detected and active TFO is disabled.

Signed-off-by: Wei Wang 
Acked-by: Yuchung Cheng 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller

tcp: remove tcp_tw_recycle

2017-03-17T03:33:56+00:00

The tcp_tw_recycle was already broken for connections
behind NAT, since the per-destination timestamp is not
monotonically increasing for multiple machines behind
a single destination address.

After the randomization of TCP timestamp offsets
in commit 8a5bd45f6616 (tcp: randomize tcp timestamp offsets
for each connection), the tcp_tw_recycle is broken for all
types of connections for the same reason: the timestamps
received from a single machine is not monotonically increasing,
anymore.

Remove tcp_tw_recycle, since it is not functional. Also, remove
the PAWSPassive SNMP counter since it is only used for
tcp_tw_recycle, and simplify tcp_v4_route_req and tcp_v6_route_req
since the strict argument is only set when tcp_tw_recycle is
enabled.

Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: Eric Dumazet 
Signed-off-by: Neal Cardwell 
Signed-off-by: Yuchung Cheng 
Cc: Lutz Vieweg 
Cc: Florian Westphal 
Signed-off-by: David S. Miller

net: add LINUX_MIB_PFMEMALLOCDROP counter

2017-02-03T04:34:19+00:00

Debugging issues caused by pfmemalloc is often tedious.

Add a new SNMP counter to more easily diagnose these problems.

Signed-off-by: Eric Dumazet 
Cc: Josef Bacik 
Acked-by: Josef Bacik 
Signed-off-by: David S. Miller

net: remove bh disabling around percpu_counter accesses

2017-01-20T16:27:22+00:00

Shaohua Li made percpu_counter irq safe in commit 098faf5805c8
("percpu_counter: make APIs irq safe")

We can safely remove BH disable/enable sections around various
percpu_counter manipulations.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

ipv4: Namespaceify tcp_tw_recycle and tcp_max_tw_buckets knob

2016-12-29T16:38:31+00:00

Different namespace application might require fast recycling
TIME-WAIT sockets independently of the host.

Signed-off-by: Haishuang Yan 
Signed-off-by: David S. Miller

net: Suppress the "Comparison to NULL could be written" warnings

2016-09-30T05:50:45+00:00

This is to suppress the checkpatch.pl warning "Comparison to NULL
could be written". No functional changes here.

Signed-off-by: Jia He 
Signed-off-by: David S. Miller