From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.lang.hm (unknown [66.167.227.145]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 7496D3B29D for ; Thu, 2 Dec 2021 14:33:46 -0500 (EST) Received: from dlang-mobile (unknown [10.2.2.69]) by mail.lang.hm (Postfix) with ESMTP id 4C0D41149FA; Thu, 2 Dec 2021 11:33:45 -0800 (PST) Date: Thu, 2 Dec 2021 11:33:45 -0800 (PST) From: David Lang To: Dave Collier-Brown cc: bloat@lists.bufferbloat.net In-Reply-To: <5f2d6491-c153-52db-0992-a90d73ec8831@indexexchange.com> Message-ID: <2ssp2oqn-1os2-n841-574q-613no587856p@ynat.uz> References: <1638390391.091227727@apps.rackspace.com> <5f2d6491-c153-52db-0992-a90d73ec8831@indexexchange.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Re: [Bloat] [Cerowrt-devel] uplink bufferbloat and scheduling problems 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: Thu, 02 Dec 2021 19:33:46 -0000 On Thu, 2 Dec 2021, Dave Collier-Brown wrote: > A different hand-wave: what about "packet trains"? They make using > queuing networks mis-estimate, do they come close together enough that > routers need to be sensitive to them, and affect the number of packets > they need to buffer? I think that's going to depend on how big the burst is, and how sensitive it is to packet loss. If it's not big, and is sensitive to packet loss, then it's not a big deal to buffer it. But if it's 'too big', it will interfere with others. since it's impossible to know how big they are going to be, especially compared to others, it seems to work pretty well to just not try to account for them. I believe that current best options do give new flows a bit more leeway before throttling them, so if it is a small burst at the start of a flow, it will go through quickly, and only start getting throttled if the volume remains high. Remember, perfect is the enemy of better. You can always craft a case where perfect knowledge of future traffic would let you optimize in a different way, but since such knowledge doesn't exist in the real world, attempts to account for everything are doomed to failure. David Lang