[PATCH net-next 2/3] tcp: adjust sndbuf according to sk_reserved_mem
From: Wei Wang <hidden>
Date: 2021-09-27 18:25:36
Subsystem:
networking [general], networking [sockets], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Willem de Bruijn, Neal Cardwell, Linus Torvalds
If user sets SO_RESERVE_MEM socket option, in order to fully utilize the reserved memory in memory pressure state on the tx path, we modify the logic in sk_stream_moderate_sndbuf() to set sk_sndbuf according to available reserved memory, instead of MIN_SOCK_SNDBUF, and adjust it when new data is acked. Signed-off-by: Wei Wang <redacted> Signed-off-by: Eric Dumazet <edumazet@google.com> --- include/net/sock.h | 1 + net/ipv4/tcp_input.c | 14 ++++++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index b0df2d3843fd..e6ad628adcd2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h@@ -2388,6 +2388,7 @@ static inline void sk_stream_moderate_sndbuf(struct sock *sk) return; val = min(sk->sk_sndbuf, sk->sk_wmem_queued >> 1); + val = max_t(u32, val, sk_unused_reserved_mem(sk)); WRITE_ONCE(sk->sk_sndbuf, max_t(u32, val, SOCK_MIN_SNDBUF)); }
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 141e85e6422b..a7611256f235 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c@@ -5381,7 +5381,7 @@ static int tcp_prune_queue(struct sock *sk) return -1; } -static bool tcp_should_expand_sndbuf(const struct sock *sk) +static bool tcp_should_expand_sndbuf(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk);
@@ -5392,8 +5392,18 @@ static bool tcp_should_expand_sndbuf(const struct sock *sk) return false; /* If we are under global TCP memory pressure, do not expand. */ - if (tcp_under_memory_pressure(sk)) + if (tcp_under_memory_pressure(sk)) { + int unused_mem = sk_unused_reserved_mem(sk); + + /* Adjust sndbuf according to reserved mem. But make sure + * it never goes below SOCK_MIN_SNDBUF. + * See sk_stream_moderate_sndbuf() for more details. + */ + if (unused_mem > SOCK_MIN_SNDBUF) + WRITE_ONCE(sk->sk_sndbuf, unused_mem); + return false; + } /* If we are under soft global TCP memory pressure, do not expand. */ if (sk_memory_allocated(sk) >= sk_prot_mem_limits(sk, 0))
--
2.33.0.685.g46640cef36-goog