From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lawrence Brakmo Subject: Re: [RFC PATCH net-next] tcp: add NV congestion control Date: Mon, 6 Jul 2015 22:40:17 +0000 Message-ID: References: <1435886484-1709996-1-git-send-email-brakmo@fb.com> <20150703.094704.283183007204034386.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "netdev@vger.kernel.org" , Kernel Team , Neal Cardwell To: David Miller Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:15243 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753687AbbGFWl4 convert rfc822-to-8bit (ORCPT ); Mon, 6 Jul 2015 18:41:56 -0400 In-Reply-To: <20150703.094704.283183007204034386.davem@davemloft.net> Content-Language: en-US Content-ID: Sender: netdev-owner@vger.kernel.org List-ID: On 7/3/15, 9:47 AM, "David Miller" wrote: >From: Lawrence Brakmo >Date: Thu, 2 Jul 2015 18:21:24 -0700 > >> This is a request for comments. >>=20 >> TCP-NV (New Vegas) is a major update to TCP-Vegas. An earlier versio= n of >> NV was presented at 2010's LPC (slides). It is a delayed based >> congestion avoidance for the data center. This version has been test= ed >> within a 10G rack where the HW RTTs are 20-50us. >>=20 >> A description of TCP-NV, including implementation and experimental >> results, can be found at: >> http://www.brakmo.org/networking/tcp-nv/TCPNV.html >>=20 >> The current version includes many module parameters to support >> experimentation with the parameters. >>=20 >> Signed-off-by: Lawrence Brakmo > >I'm disappointed in the skb->cb[] size increase, like Eric. This >severely negatively impacts everyone on every Linux system in the >world, not just people using NV. > >The performance implications from increasing sk_buff by even 1 byte in >size are absolutely non-trivial. I will look into Neal=B9s comment regarding using a union in the skb->c= b[] so I don=B9t have to increase skb->cb[] size.