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b0e01253a7
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Eric Dumazet b0e01253a7 tcp: refine tcp_prune_ofo_queue() logic 
After commits 36a6503fed ("tcp: refine tcp_prune_ofo_queue()
to not drop all packets") and 72cd43ba64
("tcp: free batches of packets in tcp_prune_ofo_queue()")
tcp_prune_ofo_queue() drops a fraction of ooo queue,
to make room for incoming packet.

However it makes no sense to drop packets that are
before the incoming packet, in sequence space.

In order to recover from packet losses faster,
it makes more sense to only drop ooo packets
which are after the incoming packet.

Tested:
packetdrill test:
   0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [3800], 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 7>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 0>
  +.1 < . 1:1(0) ack 1 win 1024
   +0 accept(3, ..., ...) = 4

 +.01 < . 200:300(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1 <nop,nop, sack 200:300>

 +.01 < . 400:500(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1 <nop,nop, sack 400:500 200:300>

 +.01 < . 600:700(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1 <nop,nop, sack 600:700 400:500 200:300>

 +.01 < . 800:900(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1 <nop,nop, sack 800:900 600:700 400:500 200:300>

 +.01 < . 1000:1100(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1 <nop,nop, sack 1000:1100 800:900 600:700 400:500>

 +.01 < . 1200:1300(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1 <nop,nop, sack 1200:1300 1000:1100 800:900 600:700>

// this packet is dropped because we have no room left.
 +.01 < . 1400:1500(100) ack 1 win 1024

 +.01 < . 1:200(199) ack 1 win 1024
// Make sure kernel did not drop 200:300 sequence
   +0 > . 1:1(0) ack 300 <nop,nop, sack 1200:1300 1000:1100 800:900 600:700>
// Make room, since our RCVBUF is very small
   +0 read(4, ..., 299) = 299

 +.01 < . 300:400(100) ack 1 win 1024
   +0 > . 1:1(0) ack 500 <nop,nop, sack 1200:1300 1000:1100 800:900 600:700>

 +.01 < . 500:600(100) ack 1 win 1024
   +0 > . 1:1(0) ack 700 <nop,nop, sack 1200:1300 1000:1100 800:900>

   +0 read(4, ..., 400) = 400

 +.01 < . 700:800(100) ack 1 win 1024
   +0 > . 1:1(0) ack 900 <nop,nop, sack 1200:1300 1000:1100>

 +.01 < . 900:1000(100) ack 1 win 1024
   +0 > . 1:1(0) ack 1100 <nop,nop, sack 1200:1300>

 +.01 < . 1100:1200(100) ack 1 win 1024
// This checks that 1200:1300 has not been removed from ooo queue
   +0 > . 1:1(0) ack 1300

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20221101035234.3910189-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-11-01 21:19:58 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-10-27 16:56:36 -07:00
block block-6.1-2022-10-20 2022-10-21 15:14:14 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation dt-bindings: net: snps,dwmac: Document queue config subnodes 2022-10-31 09:08:42 +00:00
drivers net: systemport: Add support for RDMA overflow statistic counter 2022-10-31 20:05:03 -07:00
fs execve fixes for v6.1-rc3 2022-10-27 13:16:36 -07:00
include net: dropreason: add SKB_DROP_REASON_FRAG_TOO_FAR 2022-10-31 20:14:27 -07:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring/net: fail zc sendmsg when unsupported by socket 2022-10-22 08:43:03 -06:00
ipc - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-10-24 13:44:11 -07:00
lib Including fixes from 802.15.4 (Zigbee et al.). 2022-10-27 13:36:59 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/huge_memory: do not clobber swp_entry_t during THP split 2022-10-20 21:27:24 -07:00
net tcp: refine tcp_prune_ofo_queue() logic 2022-11-01 21:19:58 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-10-20 17:49:10 -07:00
security selinux: enable use of both GFP_KERNEL and GFP_ATOMIC in convert_context() 2022-10-19 09:55:53 -04:00
sound sound fixes for 6.1-rc1 2022-10-14 13:22:14 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2022-10-27 16:56:36 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm: Add support for arch compat vm ioctls 2022-10-22 05:15:23 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap mailmap: update email for Qais Yousef 2022-10-20 21:27:21 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: phy: Add driver for Motorcomm yt8521 gigabit ethernet phy 2022-10-31 10:51:54 +00:00
Makefile Linux 6.1-rc2 2022-10-23 15:27:33 -07:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.