From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-x229.google.com (mail-oi1-x229.google.com [IPv6:2607:f8b0:4864:20::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 9C3893CB37 for ; Mon, 5 Aug 2019 15:54:09 -0400 (EDT) Received: by mail-oi1-x229.google.com with SMTP id m206so63092157oib.12 for ; Mon, 05 Aug 2019 12:54:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=7S9/qnYHrFJfUQahUpeSgCeE+YRSHuIaEKuyahSm7S0=; b=FZy4sxOCmn/NK2zJag4OMbiGXfCUYsRIW7vFPQ36Fogb6hJgUpOfOTaoS1QAbiVH7r GfcyJhcMrI3izibI/J8wIwH+FPBXHduhs5FxofpGcELWfYUYWRuY2C/UO2ySOZp9KyEx /xtmWOne8MvA1yqxiMe5FqRZEtlTjEliab4H8guEaZbar/aY3Ab8Z/0Yrq4MCii1+nN9 BJSNDf5yspvbOPcOYCPXmWjfqoQhb/K8qOfe85T8yT9FfcQjR2Ms3NceGjwU77UoDJtO DwUGljCig6OX8m80A2vtZVKw6irqiNQPhGdLVzjGncZt4+nqByAi6jDm25lENnu5n+fm DlKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=7S9/qnYHrFJfUQahUpeSgCeE+YRSHuIaEKuyahSm7S0=; b=nZCU4rxwJ7VfHZgRqDoTbtPvlJpH5PHC4RQla0fVc5zscfbpwpmLs1OZn/Fks6rE3h EbCi7GuqnDOPMZW5pco4bRL1czPMX5V5vI0Z6Gzg3fG+S3fBw7JL/HQm6vsNNYpzBKVX /lgGs3e5hCQKAPPcIYTk2Rp1PjnmeR4pVA/HOwdSdmoITXP3J9PanDMOQYNUGphpD5JU I1GLduEDBm6j39njmJuc3pAHz8OAvmDL5c/ft1x77AiIbCbe4R3nd9Y3KUS0daLP4KBb qpWR9SQvS0O9wtEwfJVpqGZT+ZC4PU5IJk9IXv0lsYarIO4/7hO4R3ZuJQ7E4PjB2FqS 7emg== X-Gm-Message-State: APjAAAViy8uFLAfOc2bnNdRPxD5dHc/XYsX7JfjWiDcbgxg60sHJSfBT lN+oejuEmyS+NE9Nqd6qa3IdpLfoBqDPNEiH2mM= X-Google-Smtp-Source: APXvYqyqUIgLtpXfD09xC18zN6v/CHD2k0/rNts/vUMsRVlBWffBjJCZMcv5fEtqxqnGvygIFALyreB12WKby8W63Fk= X-Received: by 2002:a02:c7c9:: with SMTP id s9mr28995jao.82.1565034848894; Mon, 05 Aug 2019 12:54:08 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Mon, 5 Aug 2019 12:53:57 -0700 Message-ID: To: Jonathan Morton Cc: ECN-Sane Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Ecn-sane] net-next dctcp mod question X-BeenThere: ecn-sane@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussion of explicit congestion notification's impact on the Internet List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Aug 2019 19:54:09 -0000 On Mon, Aug 5, 2019 at 12:10 PM Jonathan Morton wro= te: > > > On 5 Aug, 2019, at 9:21 pm, Dave Taht wrote: > > > > The SCE tree had two key looking modifications to it that seem to have > > been superceded by net-next. > > > > My reading of the remaining differences seem to be resolved in the > > state machine where setting the last portion > > of the SCE patch appears to do a decrease on multiple losses. ? Can I > > not forward port these? > > I basically gave up on the original DCTCP code, and re-implemented it nea= rly from scratch for DCTCP-SCE. In the process I deleted a lot of unnecess= ary complications which actually slowed the response by about 1 RTT, and fi= xed the various bugs which stopped it from responding correctly to loss and= RFC-3168 CE marks (though the latter was by design in the original). Yes, your dctcp_sce.c ( https://github.com/chromi/sce/blob/sce/net/ipv4/tcp_dctcp.c ) is a ton easier to read than the mainline one. (and compared to, like bbrv2, a marvel in simplicity) > > I noticed that work had been done on the original when I tried to apply t= he SCE changes as a patch over the Raspberry Pi tree. Everything applied c= leanly besides that. I just deleted that part of the patch and moved on wi= thout investigating more deeply. OK. Hopefully someone more familiar with the logic will show up. > > Usefully, you can simulate how DCTCP is supposed to work by mangling CE m= arks into SCE ones at the receiver (SCE enabled), running DCTCP-SCE at the = sender, and inserting your choice of CE marking scheme in the middle. We d= id that in Montreal to substantiate our calculation of how TCP Prague would= react to Codel if it worked as designed. Yep. I was/am mostly concerned that linux net-next tcp_dctcp.c is still not reacting properly to loss. > - Jonathan Morton > --=20 Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-205-9740