From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from outbound01.roaringpenguin.co.uk (outbound01.roaringpenguin.co.uk [109.69.238.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 232C53B2A4 for ; Wed, 22 Nov 2017 05:31:57 -0500 (EST) Received: from relay.smtp.pnsol.com (ec2-54-246-165-192.eu-west-1.compute.amazonaws.com [54.246.165.192]) by outbound01.roaringpenguin.co.uk (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id vAMAVrxU016173 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA256 bits=256 verify=NOT); Wed, 22 Nov 2017 10:31:55 GMT Received: from mail.la.pnsol.com ([172.20.5.206]) by relay.smtp.pnsol.com with esmtp (Exim 4.82) (envelope-from ) id 1eHSJE-0003Pt-Hi; Wed, 22 Nov 2017 10:31:12 +0000 Received: from git.pnsol.com ([172.20.5.238] helo=roam.smtp.pnsol.com) by mail.la.pnsol.com with esmtp (Exim 4.76) (envelope-from ) id 1eHSJp-0000qB-60; Wed, 22 Nov 2017 10:31:49 +0000 Received: from [172.20.5.110] by roam.smtp.pnsol.com with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.82) (envelope-from ) id 1eHSJo-00007e-Mw; Wed, 22 Nov 2017 10:31:48 +0000 Content-Type: multipart/signed; boundary="Apple-Mail=_AC498369-7ED1-4459-8EBD-598B0A4DBB59"; protocol="application/pgp-signature"; micalg=pgp-sha512 Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) From: Neil Davies X-Mailbutler-Link-Tracking-Uuid: In-Reply-To: <20171121190826.5B80540605C@ip-64-139-1-69.sjc.megapath.net> Date: Wed, 22 Nov 2017 10:31:36 +0000 Cc: bloat@lists.bufferbloat.net Message-Id: <1CE2F13E-A918-4EC3-AAEF-3F92DA51C6E3@pnsol.com> References: <20171121190826.5B80540605C@ip-64-139-1-69.sjc.megapath.net> To: Hal Murray X-Mailer: Apple Mail (2.3273) X-Spam-Score: undef - relay 54.246.165.192 marked with skip_spam_scan X-CanIt-Geo: ip=54.246.165.192; country=IE; region=Leinster; city=Dublin; latitude=53.3389; longitude=-6.2595; http://maps.google.com/maps?q=53.3389,-6.2595&z=6 X-CanItPRO-Stream: pnsol-com:outbound (inherits from pnsol-com:default, PredictableNetworkSolutions:default, Wholesale:default, CTL:default, base:default) X-Canit-Stats-ID: Bayes signature not available X-CanIt-Archive-Cluster: Rl4fxI1RVOq/TTUYGiKHQwqlXy8 X-CanIt-Archived-As: pnsol-com/20171122 / 07UAWvSCM X-Scanned-By: CanIt (www . roaringpenguin . com) on 109.69.238.88 Subject: Re: [Bloat] Steam In Home Streaming on ath9k wifi 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: Wed, 22 Nov 2017 10:31:57 -0000 --Apple-Mail=_AC498369-7ED1-4459-8EBD-598B0A4DBB59 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Hal We use this approach to automatically manage measurements. There are a few more issues - the relative drift between the two clocks = can be as high as 200ppm, though typically 50-75ppm is what we observe, but = this drift is monotonic. Also NTP can make changes at one (or both) ends - they show up as = distinct direction changes in the drift. This gives a limit (or a measurement error function you have to work = within). Neil > On 21 Nov 2017, at 19:08, Hal Murray wrote: >=20 >> Right, no idea how Windows drivers behave. But odds are that the = bottleneck >> is at the client, since that often has worse antennas than the AP. If = you're >> in a position to take packet captures at both clients and AP you may = be able >> to figure it out; may require tightly synchronised clocks to do = properly, >> though. >=20 > It should be reasonable to synchronize the clocks at both ends well = enough. >=20 > If that doesn't work and/or is inconvient, you could post process one = trace > to adjust the time stamps. The idea is to scan both traces in = parallel to > find the minimum transit times in each direction, then adjust the time = stamps > on one end to allocate half the total time to each direction. It = would > obviously be handy to have a few pings during a period of low traffic = for > calibration. >=20 > ------- >=20 > There are two dimensions to clocks. One is the current time. The = other is > the frequency. If the frequency is off, the clock will drift. = (ntpd's drift > correction is usually stored in someplace like /var/lib/ntp/ntp.drift) >=20 > Unless you are interested in long runs, the clock will not drift far = enough > to be a serious problem, so all you have to do is get the time right = before > starting a run. >=20 > You might want to kill ntpd on the wifi end so it doesn't get confused = and yank the clock around. >=20 >=20 > -- > These are my opinions. I hate spam. >=20 >=20 >=20 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat >=20 >=20 > -- > BEGIN-ANTISPAM-VOTING-LINKS > ------------------------------------------------------ >=20 > Teach CanIt if this mail (ID 03UAH8AV8) is spam: > Spam: = https://portal.roaringpenguin.co.uk/canit/b.php?c=3Ds&i=3D03UAH8AV8&m=3D09= f8fdc3b5f4&rlm=3Dpnsol-com&t=3D20171121 > Not spam: = https://portal.roaringpenguin.co.uk/canit/b.php?c=3Dn&i=3D03UAH8AV8&m=3D09= f8fdc3b5f4&rlm=3Dpnsol-com&t=3D20171121 > Forget vote: = https://portal.roaringpenguin.co.uk/canit/b.php?c=3Df&i=3D03UAH8AV8&m=3D09= f8fdc3b5f4&rlm=3Dpnsol-com&t=3D20171121 > ------------------------------------------------------ > END-ANTISPAM-VOTING-LINKS >=20 --Apple-Mail=_AC498369-7ED1-4459-8EBD-598B0A4DBB59 Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJaFVIJAAoJEPmpMHCy/udqK0IP/26Z4vCe01YjnKxUfWIpXorY Zj44rTZY/DOSUN5wOkpxVcW2AAYU8CTpWFDAfD014xNvXGmu2/ZskMQc/w85SMSX rUwLw2ASuCRoEBMb9cHut9pWwQxyXNx0wuMhW4/+jG0r+rPF6+6wIavGLqEtOVpR 1VIeqtkc+zh6a4uC00ZPe+D8EBxbKoX+jTZaTW0ulp8rWKdtGQa/SkkQ9IIvU22r UB5vPxgbyO8MNjg242gD57M5CkULZhtip9qStfUbC2KSofKqdm681i12TYzPfoXt RnKkJDZIx/ISxInIbvVynit6by/cSh6IpRRxtsUPiRVy8xnamCWSFh+UKoz8wMCH 8pS2XaTnICG85aZHSL9OauwRRFHkML4AipqQIBMmqAjBupOBw+a5hKSJR4sxXSJ7 VKj7bqmMtJ2ota6cYLtsWICSGkgW3azjb7i+QMEEcr/PjsdX9121AJRWc8mIO4Fk yns2MHfx53Ko6N3kytKIt8hByuWwGLbpCnuICD19m6CPkXadoXBjT9pEaQTGTXv9 HJFZzj8BG8hZ2yP2F5HTankwf/9FGXy5JKJgZmRbr7RLtLYMMJFgqAN0EO9L0mDx 40CpGFuAkdUbHws09bbtJSW9WuieYpc+scfKkTT3SENi25ZKpof0mglkg7Hd//vh cD3m4axad6H2OnkqarYC =N/MD -----END PGP SIGNATURE----- --Apple-Mail=_AC498369-7ED1-4459-8EBD-598B0A4DBB59--