From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-x831.google.com (mail-qt1-x831.google.com [IPv6:2607:f8b0:4864:20::831]) (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 2F5183B29D for ; Mon, 5 Apr 2021 11:57:23 -0400 (EDT) Received: by mail-qt1-x831.google.com with SMTP id l13so8805799qtu.9 for ; Mon, 05 Apr 2021 08:57:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:reply-to:subject:to:references:organization:message-id:date :user-agent:mime-version:in-reply-to:content-language; bh=/3aVALC+tKz1PlYL6tKaoz0//RpEpvZxcr96+ZSzcDQ=; b=EhgZT8aTfSTL38/3VOl53Q5IuDJ0i6CvwUDbGAMokh/357xsiw3YE7eKNhq4/d9dF9 ejjkQf7wKSVYoXbKqHSABF3IZDGhTAooEPinKk018j1XFiTzW1DuWciN71CWl5MbtJco ExPLD4+tLYxDnzAIoZ68mffi1mqctcb3UI+x+8h0mI9j940pKgothhCRr8JlZG7dqY8W npgAmak+ydbz/EgNQfkb9db0S8J82x8GoCORRW1GRkPqKEUhjsGk8jopf1DHgM4C1oqi aYioyXRoHF7E1QyjzkQoSWKvWl3V+Fk5gYrug0X4mViy6KhdKgMUkj/DVEnVGIsgaE1Q A+LQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:reply-to:subject:to:references:organization :message-id:date:user-agent:mime-version:in-reply-to :content-language; bh=/3aVALC+tKz1PlYL6tKaoz0//RpEpvZxcr96+ZSzcDQ=; b=Rtac7Mk8rlBrOKm2sORlzrph8mzGeh13OOy3VxMK3/YbmBMrXUd6BFDZP1/acuunsQ L0JWZgeD9rApgkVkj/v7V50YJh2qVBPWUDUbaTgTOlEdMOjpsU0rFPkTkkODps7l0RJD SZE2ptLED36etTQgv1x5JZtVukTu4xuAeUdl9lps7ZpuS5syiSfwPX5tbfuSMOz5kUO2 agdiknr2DNwFd+sKCg7yBIWlpK1qWtc3pB36kXtjF5/lw4rJqqFgm5HC3/V61W3Ni7b2 BqC9WO/tJ6Y546MFPD3Jnl/FWNNIlRjb3XLSx5QBnjG8UtMiLuJ3AiOW6k/6MblikxVv YD+w== X-Gm-Message-State: AOAM531VnwOKE7PnfpkHBXT9K4nc7pkq2P1g+/cnuMFStk8djG1scNeX Dm/ujEL11fZKEU8r7kD2Vr0= X-Google-Smtp-Source: ABdhPJyh3V2yzBNGwwrYxil2c/cjaAZbNIbADgdh8B3yol+xyHds9UQGXhmciANX3/wM822b90t3dw== X-Received: by 2002:ac8:4b58:: with SMTP id e24mr22789702qts.120.1617638242791; Mon, 05 Apr 2021 08:57:22 -0700 (PDT) Received: from [192.168.7.122] ([99.241.212.236]) by smtp.gmail.com with ESMTPSA id y6sm13976576qkd.106.2021.04.05.08.57.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Apr 2021 08:57:22 -0700 (PDT) From: Dave Collier-Brown X-Google-Original-From: Dave Collier-Brown Reply-To: dave.collier-brown@indexexchange.com To: bloat@lists.bufferbloat.net References: <9A233C8C-5C48-4483-A087-AA5FE1011388@gmail.com> <20210405081355.14f10a08@hermes.local> Organization: Index Exchange Message-ID: <224ab312-d246-1c59-84d1-3ed9d8bda7f8@indexexchange.com> Date: Mon, 5 Apr 2021 11:57:20 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------25E633129F51FDDFE9AFC723" Content-Language: en-US X-Mailman-Approved-At: Mon, 05 Apr 2021 17:05:38 -0400 Subject: Re: [Bloat] Questions for Bufferbloat Wikipedia article X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Apr 2021 15:57:23 -0000 This is a multi-part message in MIME format. --------------25E633129F51FDDFE9AFC723 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit To speak to the original question, I'd say bufferbloat * is undesirable latency * was discovered when adding buffers counter-intuitively /slowed /packet flow. That's so as to catch the reader's attention and immediately cast light on the (memorable but mysterious) name. --dave On 2021-04-05 11:24 a.m., David Lang wrote: > On Mon, 5 Apr 2021, Stephen Hemminger wrote: > >> On Mon, 5 Apr 2021 08:46:15 -0400 >> Rich Brown wrote: >> >>> Dave Täht has put me up to revising the current Bufferbloat article >>> on Wikipedia (https://en.wikipedia.org/wiki/Bufferbloat) >>> >>> Before I get into it, I want to ask real experts for some >>> guidance... Here goes: >>> >>> 1) What is *our* definition of Bufferbloat? (We invented the term, >>> so I think we get to define it.) >>> a) Are we content with the definition from the bufferbloat.net site, >>> "Bufferbloat is the undesirable latency that comes from a router or >>> other network equipment buffering too much data." (This suggests >>> bufferbloat is latency, and could be measured in seconds/msec.) >>> >>> b) Or should we use something like Jim Gettys' definition from the >>> Dark Buffers article (https://ieeexplore.ieee.org/document/5755608), >>> "Bufferbloat is the existence of excessively large (bloated) buffers >>> in systems, particularly network communication systems." (This >>> suggests bufferbloat is an unfortunate state of nature, measured in >>> units of "unhappiness" :-) >>> c) Or some other definition? >>> >>> 2) All network equipment can be bloated. I have seen (but not really >>> followed) controversy regarding the amount of buffering needed in >>> the Data Center. Is it worth having the Wikipedia article >>> distinguish between Data Center equipment and CPE/home/last mile >>> equipment? Similarly, is the "bloat condition" and its mitigation >>> qualitatively different between those applications? Finally, do any >>> of us know how frequently data centers/backbone ISPs experience >>> buffer-induced latencies? What's the magnitude of the impact? >>> >>> 3) The Wikipedia article mentions guidance that network gear should >>> accommodate buffering 250 msec of traffic(!) Is this a real "rule of >>> thumb" or just an often-repeated but unscientific suggestion? Can >>> someone give pointers to best practices? >>> >>> 4) Meta question: Can anyone offer any advice on making a wholesale >>> change to a Wikipedia article? Before I offer a fork-lift >>> replacement I would a) solicit advice on the new text from this >>> list, and b) try to make contact with some of the reviewers and >>> editors who've been maintaining the page to establish some bona >>> fides and rapport... >>> >>> Many thanks! >>> >>> Rich >> >> I like to think of Bufferbloat as a combination of large buffers and >> how algorithms react to those buffers. > > I think there are two things > > 1. what bufferbloat is > >    bufferbloat is the result of memory getting cheaper faster than > bandwidth increased, combined with throughput benchmarking that > drastically penalized end-to-end retries. > > I think this definition is pretty academic and not something to worry > about using. > > 2. why it's a problem > > the problems show up when the buffer represents too much time worth of > data to transmit (the time between when the last byte in the buffer > gets inserted into the buffer and when it gets transmitted) > > So in a high bandwidth environment (like a datacenter) you can use > much larger buffers than when you are on a low bandwidth line > > David Lang > > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat -- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest dave.collier-brown@indexexchange.com | -- Mark Twain --------------25E633129F51FDDFE9AFC723 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit

To speak to the original question, I'd say bufferbloat

  • is undesirable latency
  • was discovered when adding buffers counter-intuitively slowed packet flow.

That's so as to catch the reader's attention and immediately cast light on the (memorable but mysterious) name.

--dave


On 2021-04-05 11:24 a.m., David Lang wrote:
On Mon, 5 Apr 2021, Stephen Hemminger wrote:

On Mon, 5 Apr 2021 08:46:15 -0400
Rich Brown <richb.hanover@gmail.com> wrote:

Dave Täht has put me up to revising the current Bufferbloat article on Wikipedia (https://en.wikipedia.org/wiki/Bufferbloat)

Before I get into it, I want to ask real experts for some guidance... Here goes:

1) What is *our* definition of Bufferbloat? (We invented the term, so I think we get to define it.)
a) Are we content with the definition from the bufferbloat.net site, "Bufferbloat is the undesirable latency that comes from a router or other network equipment buffering too much data." (This suggests bufferbloat is latency, and could be measured in seconds/msec.)

b) Or should we use something like Jim Gettys' definition from the Dark Buffers article (https://ieeexplore.ieee.org/document/5755608), "Bufferbloat is the existence of excessively large (bloated) buffers in systems, particularly network communication systems." (This suggests bufferbloat is an unfortunate state of nature, measured in units of "unhappiness" :-)
c) Or some other definition?

2) All network equipment can be bloated. I have seen (but not really followed) controversy regarding the amount of buffering needed in the Data Center. Is it worth having the Wikipedia article distinguish between Data Center equipment and CPE/home/last mile equipment? Similarly, is the "bloat condition" and its mitigation qualitatively different between those applications? Finally, do any of us know how frequently data centers/backbone ISPs experience buffer-induced latencies? What's the magnitude of the impact?

3) The Wikipedia article mentions guidance that network gear should accommodate buffering 250 msec of traffic(!) Is this a real "rule of thumb" or just an often-repeated but unscientific suggestion? Can someone give pointers to best practices?

4) Meta question: Can anyone offer any advice on making a wholesale change to a Wikipedia article? Before I offer a fork-lift replacement I would a) solicit advice on the new text from this list, and b) try to make contact with some of the reviewers and editors who've been maintaining the page to establish some bona fides and rapport...

Many thanks!

Rich

I like to think of Bufferbloat as a combination of large buffers and how algorithms react to those buffers.

I think there are two things

1. what bufferbloat is

   bufferbloat is the result of memory getting cheaper faster than bandwidth increased, combined with throughput benchmarking that drastically penalized end-to-end retries.

I think this definition is pretty academic and not something to worry about using.

2. why it's a problem

the problems show up when the buffer represents too much time worth of data to transmit (the time between when the last byte in the buffer gets inserted into the buffer and when it gets transmitted)

So in a high bandwidth environment (like a datacenter) you can use much larger buffers than when you are on a low bandwidth line

David Lang

_______________________________________________
Bloat mailing list
Bloat@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/bloat

-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
dave.collier-brown@indexexchange.com |              -- Mark Twain
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