tools/testing/selftests/net/packetdrill/tcp_fast_recovery_prr-ss-10pkt-lost-1.pkt

Source file repositories/reference/linux-study-clean/tools/testing/selftests/net/packetdrill/tcp_fast_recovery_prr-ss-10pkt-lost-1.pkt

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/net/packetdrill/tcp_fast_recovery_prr-ss-10pkt-lost-1.pkt
Extension
.pkt
Size
2246 bytes
Lines
73
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: tools
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
// Test PRR-slowstart implementation.
// In this variant we test a simple case where in-flight == ssthresh
// all the way through recovery, so during fast recovery we send one segment
// for each segment SACKed/ACKed.

// Set up config.
`./defaults.sh`

// Establish a connection.
    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

  +.1 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
// RTT 100ms
  +.1 < . 1:1(0) ack 1 win 320
   +0 accept(3, ..., ...) = 4

// Send 10 data segments.
   +0 write(4, ..., 10000) = 10000
   +0 > P. 1:10001(10000) ack 1

// Lost packet 1:1001.
 +.11 < . 1:1(0) ack 1 win 320 <sack 1001:2001,nop,nop>
 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:3001,nop,nop>
 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:4001,nop,nop>
// Enter fast recovery.
   +0 > . 1:1001(1000) ack 1
 +.01 %{
assert tcpi_ca_state == TCP_CA_Recovery, tcpi_ca_state
assert tcpi_snd_cwnd == 7, tcpi_snd_cwnd
assert tcpi_snd_ssthresh == 7, tcpi_snd_ssthresh
}%

// Write some more, which we will send 1 MSS at a time,
// as in-flight segments are SACKed or ACKed.
 +.01 write(4, ..., 7000) = 7000

 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:5001,nop,nop>
   +0 > . 10001:11001(1000) ack 1

 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:6001,nop,nop>
   +0 > . 11001:12001(1000) ack 1

 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:7001,nop,nop>
   +0 > . 12001:13001(1000) ack 1

 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:8001,nop,nop>
   +0 > . 13001:14001(1000) ack 1

 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:9001,nop,nop>
   +0 > . 14001:15001(1000) ack 1

 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:10001,nop,nop>
   +0 > . 15001:16001(1000) ack 1

 +.02 < . 1:1(0) ack 10001 win 320
   +0 > P. 16001:17001(1000) ack 1
// Leave fast recovery.
 +.01 %{
assert tcpi_ca_state == TCP_CA_Open, tcpi_ca_state
assert tcpi_snd_cwnd == 7, tcpi_snd_cwnd
assert tcpi_snd_ssthresh == 7, tcpi_snd_ssthresh
}%

 +.03 < . 1:1(0) ack 12001 win 320
 +.02 < . 1:1(0) ack 14001 win 320

Annotation

Implementation Notes