From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x22f.google.com (mail-oi0-x22f.google.com [IPv6:2607:f8b0:4003:c06::22f]) (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 D03B63B25E for ; Tue, 12 Jul 2016 08:13:49 -0400 (EDT) Received: by mail-oi0-x22f.google.com with SMTP id s66so19257143oif.1 for ; Tue, 12 Jul 2016 05:13:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Ww1wcdf3nPr7dIdSBrURo7p8a21jUxUFJbAbgz2fV84=; b=iz+KFjpWNIx0UjtKX/VfvXMOSh8YVFlUunCPh/CdDxiIFTZ8yvQqlVXBM7D/1bQeD7 AY/TE7OTtX5jscSR5Ugc5hhu6SKFfJZSuSPeKUCY/A+WjqF60N5k+pm8ROhidyj9Rwpb 0l6n0WvQR6sIoyq1IQO8dhrxOlU2p1VRGpzpzDAce0G7TQk+xVxygMYx0LSW2Cl3dhIT XlCh/7F4UG2YQ68vBBUMpfRzSCA3VavNZff3lGHvUUIFdzMtuYOc9rwiVWEAj7i6vchN vFrHFfO6vmYsZ7IOp5oQwEK6tg+2BA0potIbVXVuaV5j5IA1WTB1ZPb4qMplbSQ2b56X kHjA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Ww1wcdf3nPr7dIdSBrURo7p8a21jUxUFJbAbgz2fV84=; b=fZDKCW83DCHwI1apnG8l6hSduwoEfXcYs1cQsBB2/2KKTOW7QSZRp2IFCmnK0RJoZi v8Ryl8/mX6yGpqfFAeLakQwCcTfxVAjAryob6nfBXdkydspo4lFQseBdBy8ICbThn39h FCElRETpSDgoy1UPVR0v+/KoVSO3YUiZJKxT+sv2fUi9wOCP7+zre8xdb8sgkKwtsqXU b5KPAMrW22FhcuKKnb2IzLZfqdTrhnhpcOdKTap7Fdedljrfp5pPD0/xXQUCIo/JxoGI yJLC9g296XwSLbRhzoMMBK9Io6L6pkY59IRiQQ75bfxKaatwQfjz2NNFIVcGVWuAIOqz 9yxg== X-Gm-Message-State: ALyK8tKNEZNZpgnRJ505NY4VjnGthY5mlG6ac4mpUQRaQaTK++AAJoI0DQGHT0k6JKgoluz1wkJOiyRTrzM4XQ== X-Received: by 10.157.11.65 with SMTP id p1mr1007501otd.169.1468325629167; Tue, 12 Jul 2016 05:13:49 -0700 (PDT) MIME-Version: 1.0 Received: by 10.202.230.71 with HTTP; Tue, 12 Jul 2016 05:13:48 -0700 (PDT) In-Reply-To: <11fa6d16-21e2-2169-8d18-940f6dc11dca@nbd.name> References: <11fa6d16-21e2-2169-8d18-940f6dc11dca@nbd.name> From: Dave Taht Date: Tue, 12 Jul 2016 14:13:48 +0200 Message-ID: To: Felix Fietkau , make-wifi-fast@lists.bufferbloat.net Cc: linux-wireless , Michal Kazior , =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] TCP performance regression in mac80211 triggered by the fq code 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, 12 Jul 2016 12:13:49 -0000 On Tue, Jul 12, 2016 at 12:09 PM, Felix Fietkau wrote: > Hi, > > With Toke's ath9k txq patch I've noticed a pretty nasty performance > regression when running local iperf on an AP (running the txq stuff) to > a wireless client. Your kernel? cpu architecture? What happens when going through the AP to a server from the wireless client= ? Which direction? > Here's some things that I found: > - when I use only one TCP stream I get around 90-110 Mbit/s with how much cpu left over? > - when running multiple TCP streams, I get only 35-40 Mbit/s total with how much cpu left over? context switch difference between the two tests? tcp_limit_output_bytes is? got perf? > - fairness between TCP streams looks completely fine A codel will get to long term fairness pretty fast. Packet captures from a fq will show much more regular interleaving of packets, regardless. > - there's no big queue buildup, the code never actually drops any packets A "trick" I have been using to observe codel behavior has been to enable ecn on server and client, then checking in wireshark for ect(3) marked packets. > - if I put a hack in the fq code to force the hash to a constant value You could also set "flows" to 1 to keep the hash being generated, but not actually use it. > (effectively disabling fq without disabling codel), the problem > disappears and even multiple streams get proper performance. Meaning you get 90-110Mbits ? Do you have a "before toke" figure for this platform? > Please let me know if you have any ideas. I am in berlin, packing hardware... > > - Felix > -- > To unsubscribe from this list: send the line "unsubscribe linux-wireless"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html --=20 Dave T=C3=A4ht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org