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  1. 09 May, 2016 1 commit
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  11. 24 Apr, 2016 6 commits
    • Eric Dumazet's avatar
      tcp-tso: do not split TSO packets at retransmit time · 10d3be56
      Eric Dumazet authored 
      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: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      10d3be56
    • Parthasarathy Bhuvaragan's avatar
      tipc: fix stale links after re-enabling bearer · 8cee83dd
      Parthasarathy Bhuvaragan authored 
      Commit 42b18f60 ("tipc: refactor function tipc_link_timeout()"),
introduced a bug which prevents sending of probe messages during
link synchronization phase. This leads to hanging links, if the
bearer is disabled/enabled after links are up.

In this commit, we send the probe messages correctly.

Fixes: 42b18f60 ("tipc: refactor function tipc_link_timeout()")
Acked-by: default avatarJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: default avatarParthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8cee83dd
    • David S. Miller's avatar
      Merge branch 'tcp-tcstamp_ack-frag-coalesce' · 6a74c196
      David S. Miller authored 
      Martin KaFai Lau says:

====================
tcp: Handle txstamp_ack when fragmenting/coalescing skbs

This patchset is to handle the txstamp-ack bit when
fragmenting/coalescing skbs.

The second patch depends on the recently posted series
for the net branch:
"tcp: Merge timestamp info when coalescing skbs"

A BPF prog is used to kprobe to sock_queue_err_skb()
and print out the value of serr->ee.ee_data.  The BPF
prog (run-able from bcc) is attached here:

BPF prog used for testing:
~~~~~

from __future__ import print_function
from bcc import BPF

bpf_text = """

int trace_err_skb(struct pt_regs *ctx)
{
	struct sk_buff *skb = (struct sk_buff *)ctx->si;
	struct sock *sk = (struct sock *)ctx->di;
	struct sock_exterr_skb *serr;
	u32 ee_data = 0;

	if (!sk || !skb)
		return 0;

	serr = SKB_EXT_ERR(skb);
	bpf_probe_read(&ee_data, sizeof(ee_data), &serr->ee.ee_data);
	bpf_trace_printk("ee_data:%u\\n", ee_data);

	return 0;
};
"""

b = BPF(text=bpf_text)
b.attach_kprobe(event="sock_queue_err_skb", fn_name="trace_err_skb")
print("Attached to kprobe")
b.trace_print()
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      6a74c196
    • Martin KaFai Lau's avatar
      tcp: Merge txstamp_ack in tcp_skb_collapse_tstamp · 2de8023e
      Martin KaFai Lau authored 
      When collapsing skbs, txstamp_ack also needs to be merged.

Retrans Collapse Test:
~~~~~~
0.200 accept(3, ..., ...) = 4
+0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0

0.200 write(4, ..., 730) = 730
+0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0
0.200 write(4, ..., 730) = 730
+0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0
0.200 write(4, ..., 11680) = 11680

0.200 > P. 1:731(730) ack 1
0.200 > P. 731:1461(730) ack 1
0.200 > . 1461:8761(7300) ack 1
0.200 > P. 8761:13141(4380) ack 1

0.300 < . 1:1(0) ack 1 win 257 <sack 1461:2921,nop,nop>
0.300 < . 1:1(0) ack 1 win 257 <sack 1461:4381,nop,nop>
0.300 < . 1:1(0) ack 1 win 257 <sack 1461:5841,nop,nop>
0.300 > P. 1:1461(1460) ack 1
0.400 < . 1:1(0) ack 13141 win 257

BPF Output Before:
~~~~~
<No output due to missing SCM_TSTAMP_ACK timestamp>

BPF Output After:
~~~~~
<...>-2027  [007] d.s.    79.765921: : ee_data:1459

Sacks Collapse Test:
~~~~~
0.200 accept(3, ..., ...) = 4
+0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0

0.200 write(4, ..., 1460) = 1460
+0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0
0.200 write(4, ..., 13140) = 13140
+0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0

0.200 > P. 1:1461(1460) ack 1
0.200 > . 1461:8761(7300) ack 1
0.200 > P. 8761:14601(5840) ack 1

0.300 < . 1:1(0) ack 1 win 257 <sack 1461:14601,nop,nop>
0.300 > P. 1:1461(1460) ack 1
0.400 < . 1:1(0) ack 14601 win 257

BPF Output Before:
~~~~~
<No output due to missing SCM_TSTAMP_ACK timestamp>

BPF Output After:
~~~~~
<...>-2049  [007] d.s.    89.185538: : ee_data:14599
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Tested-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      2de8023e
    • Martin KaFai Lau's avatar
      tcp: Carry txstamp_ack in tcp_fragment_tstamp · b51e13fa
      Martin KaFai Lau authored 
      When a tcp skb is sliced into two smaller skbs (e.g. in
tcp_fragment() and tso_fragment()),  it does not carry
the txstamp_ack bit to the newly created skb if it is needed.
The end result is a timestamping event (SCM_TSTAMP_ACK) will
be missing from the sk->sk_error_queue.

This patch carries this bit to the new skb2
in tcp_fragment_tstamp().

BPF Output Before:
~~~~~~
<No output due to missing SCM_TSTAMP_ACK timestamp>

BPF Output After:
~~~~~~
<...>-2050  [000] d.s.   100.928763: : ee_data:14599

Packetdrill Script:
~~~~~~
+0 `sysctl -q -w net.ipv4.tcp_min_tso_segs=10`
+0 `sysctl -q -w net.ipv4.tcp_no_metrics_save=1`
+0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0 bind(3, ..., ...) = 0
+0 listen(3, 1) = 0

0.100 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7>
0.100 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7>
0.200 < . 1:1(0) ack 1 win 257
0.200 accept(3, ..., ...) = 4
+0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0

+0 setsockopt(4, SOL_SOCKET, 37, [2688], 4) = 0
0.200 write(4, ..., 14600) = 14600
+0 setsockopt(4, SOL_SOCKET, 37, [2176], 4) = 0

0.200 > . 1:7301(7300) ack 1
0.200 > P. 7301:14601(7300) ack 1

0.300 < . 1:1(0) ack 14601 win 257

0.300 close(4) = 0
0.300 > F. 14601:14601(0) ack 1
0.400 < F. 1:1(0) ack 16062 win 257
0.400 > . 14602:14602(0) ack 2
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Tested-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      b51e13fa
    • David S. Miller's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next · 11afbff8
      David S. Miller authored 
      Pablo Neira Ayuso says:

====================
Netfilter updates for net-next

The following patchset contains Netfilter updates for your net-next
tree, mostly from Florian Westphal to sort out the lack of sufficient
validation in x_tables and connlabel preparation patches to add
nf_tables support. They are:

1) Ensure we don't go over the ruleset blob boundaries in
   mark_source_chains().

2) Validate that target jumps land on an existing xt_entry. This extra
   sanitization comes with a performance penalty when loading the ruleset.

3) Introduce xt_check_entry_offsets() and use it from {arp,ip,ip6}tables.

4) Get rid of the smallish check_entry() functions in {arp,ip,ip6}tables.

5) Make sure the minimal possible target size in x_tables.

6) Similar to #3, add xt_compat_check_entry_offsets() for compat code.

7) Check that standard target size is valid.

8) More sanitization to ensure that the target_offset field is correct.

9) Add xt_check_entry_match() to validate that matches are well-formed.

10-12) Three patch to reduce the number of parameters in
    translate_compat_table() for {arp,ip,ip6}tables by using a container
    structure.

13) No need to return value from xt_compat_match_from_user(), so make
    it void.

14) Consolidate translate_table() so it can be used by compat code too.

15) Remove obsolete check for compat code, so we keep consistent with
    what was already removed in the native layout code (back in 2007).

16) Get rid of target jump validation from mark_source_chains(),
    obsoleted by #2.

17) Introduce xt_copy_counters_from_user() to consolidate counter
    copying, and use it from {arp,ip,ip6}tables.

18,22) Get rid of unnecessary explicit inlining in ctnetlink for dump
    functions.

19) Move nf_connlabel_match() to xt_connlabel.

20) Skip event notification if connlabel did not change.

21) Update of nf_connlabels_get() to make the upcoming nft connlabel
    support easier.

23) Remove spinlock to read protocol state field in conntrack.
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      11afbff8
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