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Re: [aqm] Questioning each PIE heuristic

"Rong Pan (ropan)" <ropan@cisco.com> Tue, 28 March 2017 14:17 UTC

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From: "Rong Pan (ropan)" <ropan@cisco.com>
To: Luca Muscariello <luca.muscariello@gmail.com>, "Bless, Roland (TM)" <roland.bless@kit.edu>
CC: Fred Baker <fredbaker.ietf@gmail.com>, Jonathan Morton <chromatix99@gmail.com>, tsvwg IETF list <tsvwg@ietf.org>, Bob Briscoe <ietf@bobbriscoe.net>, "De Schepper, Koen (Koen)" <koen.de_schepper@nokia.com>, Greg White <g.white@cablelabs.com>, AQM IETF list <aqm@ietf.org>, Preethi Natarajan <prenatar@cisco.com>
Thread-Topic: [aqm] Questioning each PIE heuristic
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Date: Tue, 28 Mar 2017 14:17:19 +0000
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Subject: Re: [aqm] Questioning each PIE heuristic
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Sorry for causing the confusion in choosing the word "work-conserving". If we apply AQM and can not achieving 100% line rate, i.e. losing throughput, it is a big No No. Since we are dealing with TCP traffic, excess drops can cause TCP to back off too much and under-utilize the link.

Rong

From: Luca Muscariello <luca.muscariello@gmail.com<mailto:luca.muscariello@gmail.com>>
Date: Tuesday, March 28, 2017 at 8:48 AM
To: "Bless, Roland (TM)" <roland.bless@kit.edu<mailto:roland.bless@kit.edu>>
Cc: Fred Baker <fredbaker.ietf@gmail.com<mailto:fredbaker.ietf@gmail.com>>, Jonathan Morton <chromatix99@gmail.com<mailto:chromatix99@gmail.com>>, tsvwg IETF list <tsvwg@ietf.org<mailto:tsvwg@ietf.org>>, Bob Briscoe <ietf@bobbriscoe.net<mailto:ietf@bobbriscoe.net>>, "De Schepper, Koen (Koen)" <koen.de_schepper@nokia.com<mailto:koen.de_schepper@nokia.com>>, Rong Pan <ropan@cisco.com<mailto:ropan@cisco.com>>, Greg White <g.white@cablelabs.com<mailto:g.white@cablelabs.com>>, AQM IETF list <aqm@ietf.org<mailto:aqm@ietf.org>>, Preethi Natarajan <prenatar@cisco.com<mailto:prenatar@cisco.com>>
Subject: Re: [aqm] Questioning each PIE heuristic

Work conserving is supposed to be referring to the scheduler.
I'm not familiar with work-conservation when it refers to active queue management.
I'm not sure it is actually defined.

I can understand that an AQM can produce under utilization of the link, but that is
different to work conservation. Or is it maybe more subtle than that?

Luca

On Tue, Mar 28, 2017 at 1:48 PM, Bless, Roland (TM) <roland.bless@kit.edu<mailto:roland.bless@kit.edu>> wrote:
Hi,

Am 28.03.2017 um 13:39 schrieb Fred Baker:

> I'm not convinced I understand the definitions of "work conserving"
> and "non work conserving" in this context. A "work conserving"
> scheduling algorithm keeps an interface transmitting as long as there
> is data in the queue, while a non-work-conserving algorithm reduces
> the effective rate of the interface by spacing packets out.

+1 (that's also the definition I use, so I'm lost here too)

Regards,
 Roland

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