From nobody Wed Oct 26 12:55:21 2022 X-Original-To: freebsd-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 4My81Y012Rz4g3Gg for ; Wed, 26 Oct 2022 12:55:45 +0000 (UTC) (envelope-from tuexen@freebsd.org) Received: from drew.franken.de (drew.ipv6.franken.de [IPv6:2001:638:a02:a001:20e:cff:fe4a:feaa]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.franken.de", Issuer "Sectigo RSA Domain Validation Secure Server CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4My81W69Pnz4506; Wed, 26 Oct 2022 12:55:43 +0000 (UTC) (envelope-from tuexen@freebsd.org) Received: from smtpclient.apple (unknown [IPv6:2003:a:e03:d412:89ab:7a74:30b8:b7f]) (Authenticated sender: macmic) by drew.franken.de (Postfix) with ESMTPSA id 9DBB07174AEB8; Wed, 26 Oct 2022 14:55:32 +0200 (CEST) Content-Type: text/plain; charset=us-ascii 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 (Mac OS X Mail 16.0 \(3731.200.110.1.12\)) Subject: Re: Too aggressive TCP ACKs From: tuexen@freebsd.org In-Reply-To: Date: Wed, 26 Oct 2022 14:55:21 +0200 Cc: Hans Petter Selasky , Zhenlei Huang , freebsd-net@freebsd.org Content-Transfer-Encoding: 7bit Message-Id: <4E92E238-798B-4293-B0D2-81E3FCB92E34@freebsd.org> References: <75D35F36-7759-4168-ADBA-C2414F5B53BC@gmail.com> <712641B3-5196-40CC-9B64-04637F16F649@lurchi.franken.de> <62A0DD30-B3ED-48BE-9C01-146487599092@gmail.com> <0FED34A9-D093-442A-83B7-08C06D11F8B5@lurchi.franken.de> <330A9146-F7CC-4CAB-9003-2F90B872AC3E@gmail.com> <1ed66217-5463-fd4d-7e7a-58d9981bc44c@selasky.org> To: Tom Jones X-Mailer: Apple Mail (2.3731.200.110.1.12) X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00 autolearn=disabled version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on mail-n.franken.de X-Rspamd-Queue-Id: 4My81W69Pnz4506 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=softfail (mx1.freebsd.org: 2001:638:a02:a001:20e:cff:fe4a:feaa is neither permitted nor denied by domain of tuexen@freebsd.org) smtp.mailfrom=tuexen@freebsd.org X-Spamd-Result: default: False [-2.60 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.999]; MV_CASE(0.50)[]; MIME_GOOD(-0.10)[text/plain]; FROM_NO_DN(0.00)[]; MLMMJ_DEST(0.00)[freebsd-net@freebsd.org]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; R_DKIM_NA(0.00)[]; ASN(0.00)[asn:680, ipnet:2001:638::/32, country:DE]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_SPF_SOFTFAIL(0.00)[~all]; RCPT_COUNT_THREE(0.00)[4]; FREEFALL_USER(0.00)[tuexen]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; TO_DN_SOME(0.00)[]; TAGGED_RCPT(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DMARC_NA(0.00)[freebsd.org]; FREEMAIL_CC(0.00)[selasky.org,gmail.com,freebsd.org] X-ThisMailContainsUnwantedMimeParts: N > On 26. Oct 2022, at 10:57, Tom Jones wrote: > > On Sat, Oct 22, 2022 at 12:14:25PM +0200, Hans Petter Selasky wrote: >> Hi, >> >> Some thoughts about this topic. >> >> Delaying ACKs means loss of performance when using Gigabit TCP >> connections in data centers. There it is important to ACK the data as >> quick as possible, to avoid running out of TCP window space. Thinking >> about TCP connections at 30 GBit/s and above! >> >> I think the implementation should be exactly like it is. >> >> There is a software LRO in FreeBSD to coalesce the ACKs before they hit >> the network stack, so there are no real problems there. >> > > Changing the ACK ratio seems to be okay in most cases, a paper I wrote > about this was published this week: > > https://onlinelibrary.wiley.com/doi/10.1002/sat.1466 > > It focuses on QUIC, but congestion control dynamics don't change with > the protocol. You should be able to read there, but if not I'm happy to > send anyone a pdf. Is QUIC using an L=2 for ABC? Best regards Michael > > - Tom