From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-x330.google.com (mail-ot1-x330.google.com [IPv6:2607:f8b0:4864:20::330]) (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 692F93CB37 for ; Mon, 5 Aug 2019 16:00:46 -0400 (EDT) Received: by mail-ot1-x330.google.com with SMTP id o101so86810864ota.8 for ; Mon, 05 Aug 2019 13:00:46 -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=cyuR4YEOgc8VX2WbQ+5/9xBRwEpmzcrPS4U1HxBGtrg=; b=NAxfAYD9I4zoq36tWy/1bG+DKu9uu2f+1vOCumRJpbP4o+lLpN57c4cBhcoMEPwjGH VjTk6IMzToKY+jmgREmKQgiXTbTBmickRhmu+sR1JdsIW04nlOc2lLbq05rdlMPCk5F7 1fbEbKI5pibonrkbJc85Cz6O7EeVKSa2fykwdWUNZ78OuoDp+TDcIMm1l32ve42jdxae SIvhxc9CskIb+wSkcJvFvDZhoWdijt4uOoilb8T66OS2x6qsS8AvLuakOmuaV509Kvuz 0DFHQGU6+CDeNhRfnhduo42cQPin1fAaGPjza2NB4oGzIndjpoSvprXJ6uc1sAcjBA8R fyFg== 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=cyuR4YEOgc8VX2WbQ+5/9xBRwEpmzcrPS4U1HxBGtrg=; b=EQ842L6ZQaR1tZNAcRj46wGbs8ynuBOZTKiQVBDmLlIlQKyl09aCX/Y+NnJJ2FeMAp kHqcKYxbXo2kuxxGZ8m1LWpzYgbXQHJS8z7iUgZLX3nkSXiKpJqZ7bMvU66ndU5vqBsy ZyRyWTWOKL6SjkITfI0IEpWk3m34x7LhoOJIN03O9MEjVvv4vlJJy2cxiq3FsRV7jhQV 2+mjxyhC8wvxoZXtrmlHwQEtwvYntOeB6FywZxs18QUT50uZ68XArKxdHtWVt3BAvaBM oAXmXrMG+8ats5ioSZfzY0rMVapWLTJj9gke2+JUHF8jnJRkFZDxXz7MRo1oIbAxEf8b OBdg== X-Gm-Message-State: APjAAAVIVldBK83XB7bgsE2fn0DIzhZGYrhLPvbN1cuswIbE9wXoPIic hcCa/sy5etprL3ymmG0KEa2xdaI0EFUtCoaVGl4= X-Google-Smtp-Source: APXvYqxKEIJHSMmDPQYrSHrh6M6W3csruSFm/54Ni5rdziy8MavwLLBZu+2jBUpnHtvbP0whlGOA5vkKMOplYWY9Arg= X-Received: by 2002:a5d:9d42:: with SMTP id k2mr825635iok.45.1565035245800; Mon, 05 Aug 2019 13:00:45 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Mon, 5 Aug 2019 13:00:34 -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 20:00:46 -0000 On Mon, Aug 5, 2019 at 12:53 PM Dave Taht wrote: > > On Mon, Aug 5, 2019 at 12:10 PM Jonathan Morton w= rote: > > > > > On 5 Aug, 2019, at 9:21 pm, Dave Taht wrote: > > > > > > The SCE tree had two key looking modifications to it that seem to hav= e > > > 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 n= early from scratch for DCTCP-SCE. In the process I deleted a lot of unnece= ssary complications which actually slowed the response by about 1 RTT, and = fixed the various bugs which stopped it from responding correctly to loss a= nd 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. > oops, meant to point to this: https://github.com/chromi/sce/blob/sce/net/ipv4/tcp_dctcp_sce.c I'm still not convinced either is "correct" but that's why I compile things= . > (and compared to, like bbrv2, a marvel in simplicity) > > > > > I noticed that work had been done on the original when I tried to apply= the SCE changes as a patch over the Raspberry Pi tree. Everything applied= cleanly besides that. I just deleted that part of the patch and moved on = without 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= marks into SCE ones at the receiver (SCE enabled), running DCTCP-SCE at th= e sender, and inserting your choice of CE marking scheme in the middle. We= did that in Montreal to substantiate our calculation of how TCP Prague wou= ld 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 > > > > > -- > > Dave T=C3=A4ht > CTO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-831-205-9740 --=20 Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-205-9740