tools/testing/selftests/net/packetdrill/tcp_fast_recovery_prr-ss-ack-below-snd_una-cubic.pkt

Source file repositories/reference/linux-study-clean/tools/testing/selftests/net/packetdrill/tcp_fast_recovery_prr-ss-ack-below-snd_una-cubic.pkt

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/net/packetdrill/tcp_fast_recovery_prr-ss-ack-below-snd_una-cubic.pkt
Extension
.pkt
Size
1374 bytes
Lines
42
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 verify that the sender uses SACK info on an ACK
// below snd_una.

// 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

   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 8>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
// RTT 10ms
 +.01 < . 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 1:1001,4001:5001,7001:8001.
 +.01 < . 1:1(0) ack 1 win 320 <sack 1001:2001,nop,nop>
   +0 < . 1:1(0) ack 1 win 320 <sack 1001:3001,nop,nop>
   +0 < . 1:1(0) ack 1 win 320 <sack 1001:3001 8001:9001,nop,nop>
   +0 > . 1:1001(1000) ack 1

+.012 < . 1:1(0) ack 4001 win 320 <sack 8001:9001,nop,nop>
   +0 > . 4001:7001(3000) ack 1

   +0 write(4, ..., 10000) = 10000

// The following ACK was reordered - delayed so that it arrives with
// an ACK field below snd_una. Here we check that the newly-SACKed
// 2MSS at 5001:7001 cause us to send out 2 more MSS.
+.002 < . 1:1(0) ack 3001 win 320 <sack 5001:7001,nop,nop>
   +0 > . 7001:8001(1000) ack 1
   +0 > . 10001:11001(1000) ack 1

Annotation

Implementation Notes