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[85.204.121.218]) by smtp.gmail.com with ESMTPSA id r18sm864579edl.6.2019.09.25.01.11.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2019 01:11:09 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 56A4C18063D; Wed, 25 Sep 2019 10:11:08 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Yibo Zhao Cc: Johannes Berg , linux-wireless@vger.kernel.org, make-wifi-fast@lists.bufferbloat.net, John Crispin , Lorenzo Bianconi , Felix Fietkau , linux-wireless-owner@vger.kernel.org In-Reply-To: <2f6b649dcb788222e070ebb5593918c7@codeaurora.org> References: <156889576422.191202.5906619710809654631.stgit@alrua-x1> <156889576869.191202.510507546538322707.stgit@alrua-x1> <2f6b649dcb788222e070ebb5593918c7@codeaurora.org> X-Clacks-Overhead: GNU Terry Pratchett Date: Wed, 25 Sep 2019 10:11:08 +0200 Message-ID: <87y2yc3ieb.fsf@toke.dk> MIME-Version: 1.0 X-MC-Unique: mxQaMLMWPPSC7r8joKLkrA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] [PATCH RFC/RFT 4/4] mac80211: Apply Airtime-based Queue Limit (AQL) on packet dequeue 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: Wed, 25 Sep 2019 08:11:12 -0000 Yibo Zhao writes: > So if it is going to work together with virtual time based mechanism in= =20 > the future, the Tx criteria will be met both of below conditions, > 1. Lower than g_vt > 2. Lower than IEEE80211_AIRTIME_QUEUE_LIMIT > Are we going to maintain two kinds of airtime that one is from=20 > estimation and the other is basically from FW reporting? Yes, that was my plan. For devices that don't have FW reporting of airtime, we can fall back to the estimation; but if we do have FW reporting that is most likely going to be more accurate, so better to use that for fairness... > Meanwhile, airtime_queued will also limit the situation that we only > have a station for transmission. Not sure if the peak throughput will > be impacted. I believe it may work fine with 11ac in chromiumos, how > about 11n and 11a? Well, we will need to test that, of course. But ath9k shows that it's quite possible to run with quite shallow buffers, so with a bit of tuning I think we should be fine. If anything, slower networks need *fewer* packets queued in the firmware, and it's *easier* for the host to keep up with transmission. > Anyway, I think this approach will help to improve performance of the=20 > virtual time based mechanism since it makes packets buffered in host=20 > instead of FW's deep queue. We have observed 2-clients case with=20 > different ratio in TCP fails to maintain the ratio because the packets=20 > arriving at host get pushed to FW immediately and thus the airtime=20 > weight sum is 0 in most of time meaning no TXQ in the rbtree. For UDP,=20 > if we pump load more than the PHY rate, the ratio can be maintained=20 > beacuse the FW queue is full and packtes begin to be buffered in host=20 > making TXQs staying on the rbtree for most of time. However, TCP has its= =20 > own flow control that we can not push enough load like UDP. Yes, fixing that is exactly the point of this series :) -Toke