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[185.193.85.130]) by smtp.gmail.com with ESMTPSA id r3sm914722wmg.5.2018.04.24.12.10.57 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 24 Apr 2018 12:10:58 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Pete Heist In-Reply-To: <87k1sw7jxj.fsf@toke.dk> Date: Tue, 24 Apr 2018 21:10:56 +0200 Cc: make-wifi-fast@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: References: <66BDCA6E-D7C4-4E76-8591-8FDC35B09EA3@eventide.io> <871sf495vs.fsf@toke.dk> <87po2o7lwb.fsf@toke.dk> <1BA3CECA-8C05-4E94-9E2A-1AEA3C2F20B3@eventide.io> <87k1sw7jxj.fsf@toke.dk> To: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Mailer: Apple Mail (2.3124) Subject: Re: [Make-wifi-fast] mesh deployment with ath9k driver changes X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 Apr 2018 19:10:59 -0000 > On Apr 24, 2018, at 4:34 PM, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >=20 > Not sure. You do get HOL blocking while a packet is retried, = basically. > And ath9k will keep trying way after it should have given up (up to 30 > retries per packet). If you combine this with a lot of backoff for = each > transmission (which is also quite likely in a very congested setting), > and I suppose it might be possible=E2=80=A6 So that means everyone else waits while a packet is sent and re-sent to = a station with a weak signal, for example? I see how that would wreck = the latency pretty quick with the number of stations connected, plus = channel contention with another repeater. It may be a much bigger factor = than bloat. The physical situation is that there=E2=80=99s an AP on the roof of one = cabin, and it=E2=80=99s surrounded by about 8 occupied cabins, each with = 4 kids, at least one of which is probably curled up inside using = Instagram or YouTube. Signals and tx bitrates of the stations are below, = for interest. What I=E2=80=99ll try to find out is if it=E2=80=99s the = activities of one or two devices that affect things the most, as it = appears that mean latency can suddenly go down to < 10ms and up to > = 200ms because of =E2=80=9Csomething"... root@Cabin_12:~# iw dev ap0_1 station dump | grep "signal avg" signal avg: -60 [-67, -61] dBm signal avg: -51 [-58, -52] dBm signal avg: -61 [-64, -64] dBm signal avg: -60 [-61, -69] dBm signal avg: -70 [-72, -73] dBm signal avg: -70 [-71, -79] dBm signal avg: -75 [-78, -79] dBm signal avg: -73 [-79, -76] dBm signal avg: -75 [-80, -78] dBm signal avg: -68 [-69, -74] dBm signal avg: -76 [-77, -86] dBm signal avg: -84 [-87, -88] dBm signal avg: -79 [-81, -82] dBm signal avg: -76 [-81, -78] dBm signal avg: -58 [-59, -65] dBm signal avg: -72 [-74, -79] dBm signal avg: -74 [-81, -75] dBm signal avg: -80 [-82, -84] dBm signal avg: -65 [-69, -68] dBm signal avg: -78 [-81, -81] dBm signal avg: -68 [-69, -78] dBm signal avg: -72 [-73, -81] dBm signal avg: -70 [-76, -71] dBm signal avg: -80 [-81, -89] dBm signal avg: -75 [-78, -78] dBm signal avg: -72 [-76, -74] dBm signal avg: -78 [-82, -80] dBm signal avg: -63 [-66, -68] dBm signal avg: -78 [-85, -79] dBm signal avg: -75 [-78, -78] dBm signal avg: -65 [-69, -68] dBm root@Cabin_12:~# iw dev ap0_1 station dump | grep "tx bitrate" tx bitrate: 43.3 MBit/s MCS 4 short GI tx bitrate: 58.5 MBit/s MCS 6 tx bitrate: 57.8 MBit/s MCS 5 short GI tx bitrate: 72.2 MBit/s MCS 7 short GI tx bitrate: 52.0 MBit/s MCS 5 tx bitrate: 26.0 MBit/s MCS 3 tx bitrate: 57.8 MBit/s MCS 5 short GI tx bitrate: 52.0 MBit/s MCS 5 tx bitrate: 39.0 MBit/s MCS 4 tx bitrate: 39.0 MBit/s MCS 4 tx bitrate: 19.5 MBit/s MCS 2 tx bitrate: 39.0 MBit/s MCS 4 tx bitrate: 19.5 MBit/s MCS 2 tx bitrate: 28.9 MBit/s MCS 3 short GI tx bitrate: 28.9 MBit/s MCS 3 short GI tx bitrate: 6.5 MBit/s MCS 0 tx bitrate: 39.0 MBit/s MCS 4 tx bitrate: 58.5 MBit/s MCS 6 tx bitrate: 72.2 MBit/s MCS 7 short GI tx bitrate: 26.0 MBit/s MCS 3 tx bitrate: 39.0 MBit/s MCS 4 tx bitrate: 43.3 MBit/s MCS 4 short GI tx bitrate: 43.3 MBit/s MCS 4 short GI tx bitrate: 6.5 MBit/s MCS 0 tx bitrate: 28.9 MBit/s MCS 3 short GI tx bitrate: 1.0 MBit/s tx bitrate: 6.5 MBit/s MCS 0 tx bitrate: 65.0 MBit/s MCS 7 tx bitrate: 39.0 MBit/s MCS 4 tx bitrate: 26.0 MBit/s MCS 3 tx bitrate: 1.0 MBit/s