From 7885ce0147401d5f6908ad4da660334031d836b7 Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Sat, 31 Jan 2026 23:25:01 +0100 Subject: tcp: try to avoid safer when ACKs are thinned MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add newly acked pkts EWMA. When ACK thinning occurs, select between safer and unsafe cep delta in AccECN processing based on it. If the packets ACKed per ACK tends to be large, don't conservatively assume ACE field overflow. This patch uses the existing 2-byte holes in the rx group for new u16 variables withtout creating more holes. Below are the pahole outcomes before and after this patch: [BEFORE THIS PATCH] struct tcp_sock { [...] u32 delivered_ecn_bytes[3]; /* 2744 12 */ /* XXX 4 bytes hole, try to pack */ [...] __cacheline_group_end__tcp_sock_write_rx[0]; /* 2816 0 */ [...] /* size: 3264, cachelines: 51, members: 177 */ } [AFTER THIS PATCH] struct tcp_sock { [...] u32 delivered_ecn_bytes[3]; /* 2744 12 */ u16 pkts_acked_ewma; /* 2756 2 */ /* XXX 2 bytes hole, try to pack */ [...] __cacheline_group_end__tcp_sock_write_rx[0]; /* 2816 0 */ [...] /* size: 3264, cachelines: 51, members: 178 */ } Signed-off-by: Ilpo Järvinen Co-developed-by: Chia-Yu Chang Signed-off-by: Chia-Yu Chang Acked-by: Paolo Abeni Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260131222515.8485-2-chia-yu.chang@nokia-bell-labs.com Signed-off-by: Paolo Abeni --- Documentation/networking/net_cachelines/tcp_sock.rst | 1 + 1 file changed, 1 insertion(+) (limited to 'Documentation') diff --git a/Documentation/networking/net_cachelines/tcp_sock.rst b/Documentation/networking/net_cachelines/tcp_sock.rst index 26f32dbcf6ec..563daea10d6c 100644 --- a/Documentation/networking/net_cachelines/tcp_sock.rst +++ b/Documentation/networking/net_cachelines/tcp_sock.rst @@ -105,6 +105,7 @@ u32 received_ce read_mostly read_w u32[3] received_ecn_bytes read_mostly read_write u8:4 received_ce_pending read_mostly read_write u32[3] delivered_ecn_bytes read_write +u16 pkts_acked_ewma read_write u8:2 syn_ect_snt write_mostly read_write u8:2 syn_ect_rcv read_mostly read_write u8:2 accecn_minlen write_mostly read_write -- cgit v1.2.3