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[67.160.253.209]) by smtp.gmail.com with ESMTPSA id o2-v6sm258664pfj.57.2018.10.11.22.11.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Oct 2018 22:11:38 -0700 (PDT) From: Ryan Moeller Mime-Version: 1.0 (Mac OS X Mail 12.0 \(3445.100.39\)) Subject: 11-stable TCP reassembly queue Message-Id: Date: Thu, 11 Oct 2018 22:11:36 -0700 To: net@freebsd.org X-Mailer: Apple Mail (2.3445.100.39) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.27 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Oct 2018 05:11:41 -0000 There are some reports of network dropouts associated with the max TCP = reassembly queue length: = https://forums.freenas.org/index.php?threads/11-1u6-update-transfer-aborts= -on-smb-share-mac-client.69553/ = = https://forums.freenas.org/index.php?threads/network-issues-after-upgradin= g-to-11-1-u6.69506/ = I am aware that a sysctl can be adjusted to increase the maximum queue = length if needed. However, I am curious if the default might be a bit = low. Can anyone offer some advice on how to determine a rational limit = to set? To offer an additional data point: on my own desktop system = (11.2-RELEASE-p2) there are currently 3191 discarded segments. I'm not = sure if this is an unusually high number, and I honestly wouldn't have = realized it was happening if I hadn=E2=80=99t been looking at my own = stats out of curiosity. The most significant network activity for this = machine is fetching code from GitHub or downloading package updates. I = occasionally scp files to/from a macOS laptop over wifi. It seems a bit odd that my moderate traffic would be exceeding the = default threshold at all. Is this to be expected? I saw the TCP reassembly improvements in = https://reviews.freebsd.org/D16471 = and wonder if this is perhaps related. Finally, I see that a rewrite of the TCP reassembly code addressing the = inefficiency underlying the original security concern has been committed = to 12-CURRENT, and this is great for FreeBSD 12+, but it seems like it = probably won=E2=80=99t be merged into the stable branches. Can anyone = confirm that is the case? Thanks, Ryan Moeller=