From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-x22c.google.com (mail-qt0-x22c.google.com [IPv6:2607:f8b0:400d:c0d::22c]) (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 83DF33B2A4 for ; Sat, 18 Nov 2017 14:02:05 -0500 (EST) Received: by mail-qt0-x22c.google.com with SMTP id n32so10639451qtb.2 for ; Sat, 18 Nov 2017 11:02:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=IxAWqosznLd/pXDG6x0/D/nHDKV+Ja6CdIYOsw561iI=; b=camhtorQ4DkC8ZLAIf+sYvWRUD8uH0Yq1IH3k4c5VIFsGuJaL/gJ7Q9frySa9xv+01 vcnQ35fYP+45O8JerOPV4J1xDZCdcp0xlJbdl+MpyfZsf5FCH2FgDt0OUatDOpIJJxZu O2+ZyrkfNaSpch4LyUtinITTLueu7htF6Ejy+k9pj7mgE/MKYTW6TkAy1XqV1oRT1lLU 4+Nc5GOMfEKHxXuoO3Uc5E988T6tuYyn+veNlPbQAzn47bFmbiECUvP/0Zg5Sed0TVAV QWhQIKZLMafFFFRvV+zKV+jU7RSNgg+AXSc/7U7IbMHAcaRxHYZCkVjEEKXXoN68/Gip tEmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=IxAWqosznLd/pXDG6x0/D/nHDKV+Ja6CdIYOsw561iI=; b=CMJGxN2/A6uy2HJ8tWPeSqU5XPKsIS8l1yIL0g0O+pZg3leAIaznWER8h4MHr8a/UA pFyOwz2GaJoh59aQBP1hHsVRF6VL8GwCBvY4gfO+zM1Qsz7NFgOxSH+98yqOOJY+hAHr LBowXOt+a1lidMs/cisIh5Hdv32NxLO0oSNyUvM0azpM5HOgCOpYONaTx1k3ez4dgnOC NtCf8aoEnU374XPUIE5wbQRaR874fNK2rQH2pfoHEXGWKsyS8fw4TmC8JS/iWmj2aTBC 21iUiwXxFwhNtKfzAaEQLapLWgehgPz5VeSq4pbS9I9hqE4tWIEkmEAk3LJOpnrNkVBl PoFw== X-Gm-Message-State: AJaThX7FjPsQTqfLzL8Ui6d3xiAPi/xvPhz9kLokw1W2dtSXpI4Tz7K6 kRFW5dT+7a7FkpemRNEAe+ZLnClpupQdg3rU8Gw= X-Google-Smtp-Source: AGs4zMZzncWf5P7w2M/IWX3ITa8KundlyfsKAFWOfufj9RPUsu+lWor1neTd0rX5TDK5btPy2k7vzB5A6GkIe2SbCno= X-Received: by 10.200.35.147 with SMTP id q19mr14122400qtq.262.1511031725080; Sat, 18 Nov 2017 11:02:05 -0800 (PST) MIME-Version: 1.0 Received: by 10.12.193.93 with HTTP; Sat, 18 Nov 2017 11:02:04 -0800 (PST) In-Reply-To: References: From: Dave Taht Date: Sat, 18 Nov 2017 11:02:04 -0800 Message-ID: To: Pete Heist Cc: Cake List Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Cake] [RFC PATCH 4/5] q_netem: support delivering packets in delayed time slots X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 18 Nov 2017 19:02:05 -0000 On Sat, Nov 18, 2017 at 5:18 AM, Pete Heist wrote: > > On Nov 17, 2017, at 11:55 PM,dave.taht@gmail.com wrote: > > > Slotting is a crude approximation of the behaviors of shared media such > as cable, wifi, and LTE, which gather up a bunch of packets within a > varying delay window and deliver them, relative to that, nearly all at > once. > > > Nice=E2=80=A6 Meh. It really is "crude", and I keeping kicking about ways to somehow emulate half (or less) duplex, variable rates around a mean, mcast, etc. it IS very nice to have a rate limiter that actually behaves a bit more like wifi, and I hope to also add the new ack fitering stuff to it. > > One of the things I also notice in my LAN tests is latencies for differen= t > flows staying at more or less fixed (and different) positions relative to > the mean in flent results. Those positions, and the mean, can change with > each test run. Do you think this could result from the hashing to differe= nt > hardware queues (four in my case) changing between test runs? yes if you are using bql probably. Is it sch_mq on top? > And is it > worth trying to simulate this effect, or not really? Dunno. There are a couple ways to turn it off. > Just for info, in my case (Intel i210) the hashing is documented starting= on > page 254 of the specs: > https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/i= 210-ethernet-controller-datasheet.pdf > (7.1.2.10.1 RSS Hash Function). For TCP/UDP it uses source and destinatio= n > addresses and ports. I suppose this could be smoothed over in testing by > using a spread of ports for the latency test. --=20 Dave T=C3=A4ht CEO, TekLibre, LLC http://www.teklibre.com Tel: 1-669-226-2619