From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x229.google.com (mail-oi0-x229.google.com [IPv6:2607:f8b0:4003:c06::229]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 6D6FD21F378 for ; Wed, 22 Apr 2015 14:47:29 -0700 (PDT) Received: by oiko83 with SMTP id o83so190894361oik.1 for ; Wed, 22 Apr 2015 14:47:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=wybl9b3fP849hjrUvzMMJdHOMwxQlV4jbvYQVGLw8fk=; b=aZ0FvQ6GKAb49mw/o7h5Hra08h240aGXj5+D8Yh5jgHSKXGQIFLyNa2UMtfRRhvjV8 e85DzhdymWIz7IT54d7j2ViiUi+C4I/UVus4LPk59tJ48g2oenUxQ3pxCbIBak5gA79R nucW/VplPXc5j3BYua8/91Xcw0bXei5/jSkw7PbyVmAfSGQdgPOKK1l4XO1cHmYWeaxH btHJ7FybAc/gYPOYekpjITzw0B8l9ZHafQ9TAJ7PcgGYyFDRJVi0EBwznT4m2jf/KuHc 6WhjOioHms0J4iF9qFqaG6NMquexCXlPq/uRGgfTg2mUx2x91KDSdog7HnfCoVuO2nPs JRSA== MIME-Version: 1.0 X-Received: by 10.202.216.87 with SMTP id p84mr24068905oig.133.1429739248178; Wed, 22 Apr 2015 14:47:28 -0700 (PDT) Received: by 10.202.71.139 with HTTP; Wed, 22 Apr 2015 14:47:28 -0700 (PDT) In-Reply-To: <1429738979.18561.150.camel@edumazet-glaptop2.roam.corp.google.com> References: <20150422191056.9C7AC406057@ip-64-139-1-69.sjc.megapath.net> <1429736552.18561.144.camel@edumazet-glaptop2.roam.corp.google.com> <20150422210740.GA31348@sesse.net> <1429738979.18561.150.camel@edumazet-glaptop2.roam.corp.google.com> Date: Wed, 22 Apr 2015 14:47:28 -0700 Message-ID: From: Dave Taht To: Eric Dumazet Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: Hal Murray , bloat Subject: Re: [Bloat] SO_SNDBUF and SO_RCVBUF X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Apr 2015 21:47:58 -0000 On Wed, Apr 22, 2015 at 2:42 PM, Eric Dumazet wrot= e: > On Wed, 2015-04-22 at 23:07 +0200, Steinar H. Gunderson wrote: >> On Wed, Apr 22, 2015 at 02:02:32PM -0700, Eric Dumazet wrote: >> > Yeah, the real nice thing is TCP_NOTSENT_LOWAT added in linux-3.12 >> >> But this is only for when your data could change underway, right? >> Like, not relevant for sending one big file, but might be relevant for e= .g. >> VNC (or someone mentioned the usecase of HTTP/2, where a high-priority >> request might come in, which you don't want buried behind a megabyte of >> stuff in the send queue). > > Sorry, I do not understand you. > > The nice thing about TCP_NOTSENT_LOWAT is that you no longer have to > care about choosing the 'right SO_SNDBUF' Stuart cheshire has a very nice youtube video due out soon on this option. He demonstrates the enormous difference it made in a screen sharing application... ... and there are many libs and toolkits (like X11, userspace tcp vpns, etc) that could use it. It should be going into every tcp app that might congest AND = can do more intelligent things when congested. It looks useful in web browsers also. I have no idea to what extent this socket option has been picked up by the marketplace/open source world. > > It is still CC responsibility to choose/set cwnd, but you hadn't set an > artificial cap on cwnd. > > You control the amount of 'unsent data' per socket. > > If you set a low limit, application might have to issue more send() > calls and get more EPOLLOUT events. > > This also means that if you get an abort / eof, you no longer have a > huge unsent queue that TCP API does not allow to cancel. > > https://insouciant.org/tech/prioritization-only-works-when-theres-pending= -data-to-prioritize/ > > --=20 Dave T=C3=A4ht Open Networking needs **Open Source Hardware** https://plus.google.com/u/0/+EricRaymond/posts/JqxCe2pFr67