From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x232.google.com (mail-lf0-x232.google.com [IPv6:2a00:1450:4010:c07::232]) (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 0476B3CB42 for ; Sat, 27 Jan 2018 01:35:38 -0500 (EST) Received: by mail-lf0-x232.google.com with SMTP id v188so3244701lfa.11 for ; Fri, 26 Jan 2018 22:35:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=K64Qy1WNhFCbqB9HthV0DofXUHkBqtMvOEIs3ZzDJ2M=; b=W/3kqdIZFvaUOmguANp5+lkOByx4PMc2brbmRnsGV31fDX8fw6aGIXd6flDxX2NmNH 71aa/FgoedmUVVqxn6RbNmykbrT6uBnTNWbYO/AvRBSMG9t/0IcKjqn1nLhcd6W77jyd jGibMVBWdTShFT4sHW7oeDuCzd1DOiJUFZaSlqeGByNORj+q2uigz5vUWNjwiezU+GWd GDXvNw5VWTcLPdO0LfANYJzuY/xmM9Xpn+QQY6gJnuEWWPLo8ceVCZoCv9AblS5YDQyw JeVIVwWcz57cdMUKZZH5y8mbSCEmSTLhXU+q7zZLawc63CsLgh5JtEXC7TC7rUOdMCvA 94GA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=K64Qy1WNhFCbqB9HthV0DofXUHkBqtMvOEIs3ZzDJ2M=; b=ZIINY37xSWceQ+M3CyTz8/tTR7eYT1gQatiVx4pC8oH4HKzLg8cnBhZOD7NbrhQynt 5oHnXR4OncN0wWAJPKfRJaKB+T1MR1jCsVhJtoR5asv3DSGFOKjVtm7pNRSywDEG0wAk FsX31/sPCjpIa4c5fPf7UNU+wkYAhNZ8r8Jyx1shQvuUTgYuXKDmmCPZpHCz9dv3864e WvH7Sdc21Bktl29bJmkm28u3xPlzbN7NIbr70jkjqZtlhfa1Kn0M6rAWZ8YD21ftMAy4 d8PjsxnDm0fQdV8aPR2MWKq8VrbHjPdIbYDwHS5UREk3wI5c5ecxVN0I69pO+WmiokkG 6fTw== X-Gm-Message-State: AKwxytfM2XIjeLPTb6dirsFvZrVEjCfI63N8oB9DbxkEF8m5MqzJKQyM S0xAVvPV403xVMGcNo7Blrc= X-Google-Smtp-Source: AH8x227cclqRxBrSfpyb7eV3VW4y7Dm0XQAAJYwNYBIQGhCl7cqGM2Z03jyi3BKJCuq46lOXOVfuGQ== X-Received: by 10.46.27.77 with SMTP id b74mr5967890ljb.60.1517034937862; Fri, 26 Jan 2018 22:35:37 -0800 (PST) Received: from [192.168.239.216] (83-245-232-149-nat-p.elisa-mobile.fi. [83.245.232.149]) by smtp.gmail.com with ESMTPSA id d82sm1773312lfl.23.2018.01.26.22.35.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Jan 2018 22:35:37 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\)) From: Jonathan Morton In-Reply-To: Date: Sat, 27 Jan 2018 08:35:32 +0200 Cc: bloat Content-Transfer-Encoding: quoted-printable Message-Id: <1E00955B-C1C0-42F1-9962-634A90EE78E5@gmail.com> References: To: Dave Taht X-Mailer: Apple Mail (2.3445.5.20) Subject: Re: [Bloat] 400g Tomahawk-3 chip 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: Sat, 27 Jan 2018 06:35:39 -0000 > On 27 Jan, 2018, at 5:31 am, Dave Taht wrote: >=20 > If someone could translate the "smart buffering", "flow aware" and > "mice v elephants" comments into how it actually works in the > tomahawk-3 chip... I'd love it. Just reading what you quoted, it looks like they have a big buffer which = can absorb incast bursts effectively (that is, without incurring burst = loss), but they also have flow isolation to minimise the inter-flow = induced latency that a large buffer would normally imply. That's = definitely a step forward if it's actually in the hardware at those = sorts of speeds. Precisely what counts as "a flow" is not quite clear. It could be just = IP address pairs, rather than 5-tuples. There doesn't seem to be any explicit mention of AQM here, but that = reference to RoCEv2 "congestion control" might imply something in that = category - or it could just be a back-pressure mechanism to hint local = applications. - Jonathan Morton