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tcp: Buffer sizes are *not* inherited on accept()/accept4()

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...so it's pointless to set SO_RCVBUF and SO_SNDBUF on listening
sockets.

Call tcp_sock_set_bufsize() after accept4(), for inbound sockets.

As we didn't have large buffer sizes set for inbound sockets for
a long time (they are set explicitly only if the maximum size is
big enough, more than than the ~200 KiB default), I ran some more
throughput tests for this one, and I see slightly better numbers
(say, 17 gbps instead of 15 gbps guest to host without vhost-user).

Fixes: 904b86ade7 ("tcp: Rework window handling, timers, add SO_RCVLOWAT and pools for sockets/pipes")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Stefano Brivio 2025-01-20 16:49:30 +01:00
parent c96a88d550
commit 8757834d14
1 changed files with 4 additions and 7 deletions

11
tcp.c
View file

@ -2057,6 +2057,8 @@ void tcp_listen_handler(const struct ctx *c, union epoll_ref ref,
if (s < 0)
goto cancel;
tcp_sock_set_bufsize(c, s);
/* FIXME: When listening port has a specific bound address, record that
* as our address
*/
@ -2260,7 +2262,6 @@ static int tcp_sock_init_one(const struct ctx *c, const union inany_addr *addr,
if (s < 0)
return s;
tcp_sock_set_bufsize(c, s);
return s;
}
@ -2317,9 +2318,7 @@ static void tcp_ns_sock_init4(const struct ctx *c, in_port_t port)
s = pif_sock_l4(c, EPOLL_TYPE_TCP_LISTEN, PIF_SPLICE, &inany_loopback4,
NULL, port, tref.u32);
if (s >= 0)
tcp_sock_set_bufsize(c, s);
else
if (s < 0)
s = -1;
if (c->tcp.fwd_out.mode == FWD_AUTO)
@ -2343,9 +2342,7 @@ static void tcp_ns_sock_init6(const struct ctx *c, in_port_t port)
s = pif_sock_l4(c, EPOLL_TYPE_TCP_LISTEN, PIF_SPLICE, &inany_loopback6,
NULL, port, tref.u32);
if (s >= 0)
tcp_sock_set_bufsize(c, s);
else
if (s < 0)
s = -1;
if (c->tcp.fwd_out.mode == FWD_AUTO)