From owner-freebsd-net@freebsd.org Thu Apr 5 20:46:24 2018 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E5924FA1BAB for ; Thu, 5 Apr 2018 20:46:23 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 751A470C2F for ; Thu, 5 Apr 2018 20:46:23 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id C5B0A16FDD for ; Thu, 5 Apr 2018 20:46:22 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id w35KkMdC047841 for ; Thu, 5 Apr 2018 20:46:22 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id w35KkMvo047838 for freebsd-net@FreeBSD.org; Thu, 5 Apr 2018 20:46:22 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: freebsd-net@FreeBSD.org Subject: [Bug 227303] tcp cwnd grows without bounds while app/rwnd limited, interacts badly with rwnd autosize Date: Thu, 05 Apr 2018 20:46:23 +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: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: srichard@netapp.com X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-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 MIME-Version: 1.0 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Apr 2018 20:46:24 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D227303 --- Comment #2 from Richard Scheffenegger --- After further investigation, this issue is more complex. cwnd does in fact = not grow when the transmission is rwnd limited. However, 20 sec prior to these = two burst events, during slow start, the client already signaled a large rwnd (= at least as large as when the bursts happen). And no losses occured, so cwnd d= id probably grow to the large rwnd (or very close to is) during the initial sl= ow start. Then, the client reduced rwnd to 1/2 or 1/3 of that initial value, a= nd cwnd never decays (RTT is 1ms with empty buffers, and 40ms with full buffer= s; 20 sec are eons in any case).=20 So at the time of these graphs, cwnd has no longer any valid information ab= out the state of the network, but is nevertheless used as such. Guess RFC7661 (with substituting "no transmissions" with "transmission rate= < cwnd") with it's many-rtt long decay would adress this particular issue. Can provide xpl file (but not original trace) of the entire session. --=20 You are receiving this mail because: You are the assignee for the bug.=