From nobody Fri Oct 08 09:29:32 2021 X-Original-To: net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id D66CC17E5ED5 for ; Fri, 8 Oct 2021 09:29:32 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4HQjZN5ggjz3J59 for ; Fri, 8 Oct 2021 09:29:32 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2610:1c1:1:606c::50:1d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id A2BF724B49 for ; Fri, 8 Oct 2021 09:29:32 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.5]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id 1989TWiQ034725 for ; Fri, 8 Oct 2021 09:29:32 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id 1989TWqj034724 for net@FreeBSD.org; Fri, 8 Oct 2021 09:29:32 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 258732] [tcp] TCP_MAXSEG does not work Date: Fri, 08 Oct 2021 09:29:32 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: 12.2-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: me@zhh0000zhh.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: net@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 X-ThisMailContainsUnwantedMimeParts: N https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D258732 --- Comment #10 from zhh0000zhh --- Turning off the Nagle algorithm causes the system to not wait for buffers. And any socket forwarder should have low latency. This leads to a problem for ipv6 to ipv4 forwarding where When the forwarder accepts a message from ipv4 and forwards it to the ipv6 network, the actual data sent by ipv6 will be split into two packets because the MSS of ipv4 is larger than the MSS of ipv6 (e.g. an ipv4 packet has 1460 bytes payload, this packet will be split into a 1446 bytes packet and a 14 bytes packet in ipv6, with Nagle disabled, This problem can be verified usi= ng tcpdump) This leads to a performance problem, as the ipv4 network generates one pack= et, while the ipv6 network outputs two packets, which has a significant impact = on both packet count (there is a direct correlation between packet count and performance) and effective bandwidth (excessive packet header loss leads to reduced bandwidth utilization) Inherently, the inability to set MSS does not lead to program errors, but in high performance and low latency demand scenarios can result in a significa= nt waste of resources. --=20 You are receiving this mail because: You are the assignee for the bug.=