From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bobcat.rjmcmahon.com (bobcat.rjmcmahon.com [45.33.58.123]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 737513B29E; Mon, 13 Mar 2023 16:28:30 -0400 (EDT) Received: from mail.rjmcmahon.com (bobcat.rjmcmahon.com [45.33.58.123]) by bobcat.rjmcmahon.com (Postfix) with ESMTPA id 71E231EEE8; Mon, 13 Mar 2023 13:28:29 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 bobcat.rjmcmahon.com 71E231EEE8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rjmcmahon.com; s=bobcat; t=1678739309; bh=CpCmE37MM1uPhOBQt4kSQXLmXaZcBm/4pyfLBo3OVHo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Z0jENdXB/Qx7AryKH7eIF6NL2ooc7H3oEmryu95lcndKycnxmr3MTNmwSMaCAq1zX SepTFWCcksRq3Lga01vzyxXaQp488myTbqqU+MDqQMdBC/odA2/KSeCCx5PYouIbGH 9ZzOeWldX8O4tFezY7ezsqDffOA4WaZnwlI7+4fA= MIME-Version: 1.0 Date: Mon, 13 Mar 2023 13:28:29 -0700 From: rjmcmahon To: Sebastian Moeller Cc: dan , Jeremy Austin , Rpm , libreqos , Dave Taht via Starlink , bloat In-Reply-To: <70F71290-C6CB-4D19-8A88-F0F17C0BDDA2@gmx.de> References: <1672786712.106922180@apps.rackspace.com> <77CCAD19-07E0-4F9E-88C1-D207CF7BF376@cable.comcast.com> <83ffc0dad19e3343e49271889369cefc@rjmcmahon.com> <3CD0B9E6-0B2A-4A70-8F53-ED0822DF77A6@gmx.de> <13DE6E53-665F-4C20-BBE2-70E685421E9D@gmx.de> <22C819FA-DDD7-4B9B-8C09-8008D4273287@gmx.de> <5e7fac51071bdbb20837e72e7eedfc7c@rjmcmahon.com> <3f45d2a0b6e46d7b2775fb801e805f93@rjmcmahon.com> <70F71290-C6CB-4D19-8A88-F0F17C0BDDA2@gmx.de> Message-ID: <5e0cd693c4749d128dbb48d6c1129071@rjmcmahon.com> X-Sender: rjmcmahon@rjmcmahon.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Rpm] [Starlink] [LibreQoS] [EXTERNAL] Re: Researchers Seeking Probe Volunteers in USA X-BeenThere: rpm@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: revolutions per minute - a new metric for measuring responsiveness List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Mar 2023 20:28:30 -0000 > [SM] It is doe because: > a) TCP needs some capacity estimate > b) preferably quickly > c) in a way gentler than what was used before the congestion collapse. Right, but we're moving away from capacity shortages to a focus on better latencies. The speed of distributed compute (or speed of causality) is now mostly latency constrained. Also, it's impossible per Jaffe & others for a TCP link to figure out the on-demand capacity so trying to get one via a "broken control loop" seems futile. I believe control theory states control loops need to be an order greater than what they're trying to control. I don't think an app or transport layer can do more than make educated guesses at for its control loop. Using a rating might help with that but for sure it's not accurate in space-time samples. (Note: many APs are rated 60+ Watts. What's the actual? Has to be sampled and that's only a sample. This leads to poor PoE designs - but I digress.) Let's assume the transport layer should be designed to optimize the speed of causality. This also seems impossible because the e2e jitter is worse with respect to end host discovery so there seems no way to adapt from end host only. If it's true that the end can only guess, maybe the solution domain comes from incorporating network measurements via telemetry with the ECN or equivalent? And an app can signal to the network elements to capture the e2e telemetry. I think this all has to happen within a few RTTs if the transport or host app is going to adjust. Bob