When forwarding many ports, passt can consume a lot of kernel memory
because of the many listening sockets it opens. There are not a lot
of ways we can reduce that, but here's one.
Currently we create separate listening sockets for each port for both
IPv4 and IPv6. However in Linux (and probably other platforms), it's
possible to listen for both IPv4 and IPv6 connections on an IPv6
socket. This series uses such dual stack sockets to halve the number
of listening sockets needed for TCP. When forwarding all TCP and UDP
ports, this reduces the kernel memory used from around 677 MiB to
around 487 MiB (kernel 6.0.8 on an x86_64 Fedora 37 machine).
This should also be possible for UDP, but that will require a mostly
separate implementation.
Changes since v2:
* Assorted minor polishing based on Stefano's review
David Gibson (32):
clang-tidy: Suppress warning about assignments in if statements
style: Minor corrections to function comments
tcp_splice: #include tcp_splice.h in tcp_splice.c
tcp: Remove unused TCP_MAX_SOCKS constant
tcp: Better helpers for converting between connection pointer and
index
tcp_splice: Helpers for converting from index to/from tcp_splice_conn
tcp: Move connection state structures into a shared header
tcp: Add connection union type
tcp: Improved helpers to update connections after moving
tcp: Unify spliced and non-spliced connection tables
tcp: Unify tcp_defer_handler and tcp_splice_defer_handler()
tcp: Partially unify tcp_timer() and tcp_splice_timer()
tcp: Unify the IN_EPOLL flag
tcp: Separate helpers to create ns listening sockets
tcp: Unify part of spliced and non-spliced conn_from_sock path
tcp: Use the same sockets to listen for spliced and non-spliced
connections
tcp: Remove splice from tcp_epoll_ref
tcp: Don't store hash bucket in connection structures
inany: Helper functions for handling addresses which could be IPv4 or
IPv6
tcp: Hash IPv4 and IPv4-mapped-IPv6 addresses the same
tcp: Take tcp_hash_insert() address from struct tcp_conn
tcp: Simplify tcp_hash_match() to take an inany_addr
tcp: Unify initial sequence number calculation for IPv4 and IPv6
tcp: Have tcp_seq_init() take its parameters from struct tcp_conn
tcp: Fix small errors in tcp_seq_init() time handling
tcp: Remove v6 flag from tcp_epoll_ref
tcp: NAT IPv4-mapped IPv6 addresses like IPv4 addresses
tcp_splice: Allow splicing of connections from IPv4-mapped loopback
tcp: Consolidate tcp_sock_init[46]
util: Allow sock_l4() to open dual stack sockets
util: Always return -1 on error in sock_l4()
tcp: Use dual stack sockets for port forwarding when possible
Makefile | 15 +-
conf.c | 12 +-
inany.h | 94 +++++
siphash.c | 2 +
tap.c | 6 +-
tcp.c | 981 ++++++++++++++++++++++-----------------------------
tcp.h | 11 +-
tcp_conn.h | 192 ++++++++++
tcp_splice.c | 333 +++++++----------
tcp_splice.h | 12 +-
util.c | 19 +-
11 files changed, 891 insertions(+), 786 deletions(-)
create mode 100644 inany.h
create mode 100644 tcp_conn.h
--
2.38.1