From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shan Wei Subject: Re: [PATCH net-next ] tcp: add new parameter tcp_inherit_buffsize to control the initial buffer size for new passive connetion Date: Mon, 8 May 2017 15:49:41 +0800 Message-ID: References: <1493737515.31837.42.camel@edumazet-glaptop3.roam.corp.google.com> <1493992346.7796.43.camel@edumazet-glaptop3.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev , David Miller To: Eric Dumazet Return-path: Received: from mail-pg0-f67.google.com ([74.125.83.67]:35355 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751255AbdEHHtr (ORCPT ); Mon, 8 May 2017 03:49:47 -0400 Received: by mail-pg0-f67.google.com with SMTP id i63so9483520pgd.2 for ; Mon, 08 May 2017 00:49:47 -0700 (PDT) In-Reply-To: <1493992346.7796.43.camel@edumazet-glaptop3.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: at 2017/5/5 21:52 > On Fri, 2017-05-05 at 18:22 +0800, wrote: >> >> 2017-05-02 23:05 GMT+08:00 Eric Dumazet : >> >> >> Hi Shan >> >> 1) Your patch never reached netdev, because it was sent in >> HTML format. >> >> 2) During Linus merge window, net-next is closed >> >> I am not really convinced that we need this with TCP >> autotuning anyway. >> Initial value of sk_sndbuf and sk_rcvbuf is really a hint. >> >> How often do you really tweak /proc/sys/net/ipv4 files in >> production. >> >> >> > Again you posted your reply in HTML, so netdev did not get it. Now, fix it with thunderbird instead of gmail web client. >> Historically, most products have not adjusted any wmem/rmem >> parameters. >> In our experience to adjust the parameters, you can get a better visit >> experience, faster. >> >> Now more and more products want to change this default value. >> But for a product, once we adjust the parameters, it is rarely >> adjusted. >> >> >> We hope that this patch can provide a capacity: adjust the parameters >> online and quickly take effect. >> >> Without this patch, it is time consuming for us to adjust the >> parameters and need to migrate flows. >> >> >> >> >> Please provide more information, like what actual values you >> change back >> and forth. >> >> >> >> There is no a fixed value here. big value, will take up more memory >> resources. >> But we are also willing to sacrifice memory for performance. >> >> Select the parameter value based on the characteristics of the >> product. >> >> For example, for 1MB files, we will set buffsize to 1611646 = (1MB / >> 1460) * 2244 >> Mss = 1460, SKB_TRUESIZE = 2244 >> >> >> With TCP autotuning, reach the buffer size until the cwnd equal 359 >> from 10. > Looks like a problem with autotuning because you might have HZ=100 or > HZ=250 maybe ? Indeed, HZ=250. What is the problem about autotuning with HZ=250?