From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f43.google.com (mail-pb0-f43.google.com [209.85.160.43]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 792DA201B52 for ; Fri, 31 Aug 2012 09:40:17 -0700 (PDT) Received: by pbbrq2 with SMTP id rq2so7173570pbb.16 for ; Fri, 31 Aug 2012 09:40:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:message-id:date:from:organization:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=tI6pq+lDGwdy5ZN52qFO9HRHzJWVnWkhf75da7/9Nzc=; b=gt/yV7H8d7CmrUo4N/Ak6z/QBtWqwxHOuLZUFdNBnthMh2N5KiCTdjo3Fs85zom8SK 1CuOLvEpoZLuKfBq9ZpBeUUZfO/P/xIMSc7U5VIL2wnMRYvoEXf9JQbocLbNT2oj7YEx KxvT/ZS2kFkMWcSwFbqIBWReCE8MZvPzLDYhpq5VTQmyKd57UxsCUz2Byw+NYXBZW2c3 iFOX3g8ixYo05F5FdGOglYQkuSubplET6HTjQF07ZlIA0KzHop1tvR3qlmj6SajXeDG9 3yq5LtJRQiwCnIhiFoy4KzMu5Tj1YtbTaupKCmcHHzePKSyiqRTUI2+Zy3RCmiQSCBtv 09KQ== Received: by 10.68.129.73 with SMTP id nu9mr18478835pbb.59.1346431217061; Fri, 31 Aug 2012 09:40:17 -0700 (PDT) Received: from [10.11.2.117] ([38.96.16.75]) by mx.google.com with ESMTPS id gf3sm3743497pbc.74.2012.08.31.09.40.15 (version=SSLv3 cipher=OTHER); Fri, 31 Aug 2012 09:40:16 -0700 (PDT) Sender: Jim Gettys Message-ID: <5040E8EE.2070900@freedesktop.org> Date: Fri, 31 Aug 2012 09:40:14 -0700 From: Jim Gettys Organization: Bell Labs User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: Rick Jones References: <1346396137.2586.301.camel@edumazet-glaptop> <5040DDE9.7030507@hp.com> In-Reply-To: <5040DDE9.7030507@hp.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] fq_codel : interval servo X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 31 Aug 2012 16:40:17 -0000 On 08/31/2012 08:53 AM, Rick Jones wrote: > On 08/30/2012 11:55 PM, Eric Dumazet wrote: >> On locally generated TCP traffic (host), we can override the 100 ms >> interval value using the more accurate RTT estimation maintained by TCP >> stack (tp->srtt) >> >> Datacenter workload benefits using shorter feedback (say if RTT is below >> 1 ms, we can react 100 times faster to a congestion) >> >> Idea from Yuchung Cheng. > > Mileage varies of course, but what are the odds of a datacenter's > end-system's NIC(s) being the bottleneck point? Ergo my comment about Ethernet flow control finally being possibly more help than hurt; clearly if the bottleneck is kept in the sending host more of the time, it would help. I certainly don't know how often the end-system's NIC's are the bottleneck today without flow control; maybe a datacenter type might have insight into that. - Jim