From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x236.google.com (mail-oi0-x236.google.com [IPv6:2607:f8b0:4003:c06::236]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 4199821F7EF for ; Fri, 26 Jun 2015 09:34:29 -0700 (PDT) Received: by oigx81 with SMTP id x81so79154699oig.1 for ; Fri, 26 Jun 2015 09:34:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=vHU29x5G1SLzEI/RifxlKuUoV4P5aJRjid03dKfvPuw=; b=DI8Nsfbz6/plHTS/LGfwk/6uCIZqepdsq92zzmoJlRnw+TIohl/7cpChe48YOBe9a+ 7YHcqmlzDpPV2GSTMI6EDX+H06QjXH6egHJpFhKpgmYKnleojcOQwkury8XGTx4cjqLl dzEahb5jTHnBfoB+gsq28g5WIdK9+7EC8EByZMJHkywbQBPPySOUyA5mPwHqIUSVB4hR JKiJ5B4fXpk/GJ4rE0s9tECfyoRoVFTdk0KvhrEf/amWXsyIM55tBTCgecd5Y5CJt1BM kxq7kWcmENFKooDQQH7pcqh3TLiWq1ELKS1keu2Y5FehLDoYHd4L+j9Rt0RMmSu0jim/ 8zIg== MIME-Version: 1.0 X-Received: by 10.202.91.212 with SMTP id p203mr2141553oib.108.1435336469040; Fri, 26 Jun 2015 09:34:29 -0700 (PDT) Received: by 10.202.105.129 with HTTP; Fri, 26 Jun 2015 09:34:28 -0700 (PDT) In-Reply-To: References: <26463A88-821B-44B7-A728-64BCB0B7C7BB@gmx.de> <55847E32.9000405@gmail.com> <5584823E.4040207@gmail.com> <0129B5FB-9D1B-45FF-84CA-492A6A0B638B@gmx.de> <43D5C3CE-F1F4-4BA5-AEB9-55348661C7BA@gmx.de> Date: Fri, 26 Jun 2015 09:34:28 -0700 Message-ID: From: Dave Taht To: Jonathan Morton Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] performance numbers from WRT1200AC (Re: Latest build test - new sqm-scripts seem to work; "cake overhead 40" didn't) X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Jun 2015 16:34:58 -0000 On Fri, Jun 26, 2015 at 9:18 AM, Jonathan Morton wr= ote: > Hypothesis: this might have to do with the receive path. Some devices mig= ht > have more capacity than others to buffer inbound packets until the CPU ca= n > get around to servicing them. *Good* hypothesis. I am certain I have seen this on multiple occasions on other hardware. Hard to confirm. Wet paint... so I finally got off my arse and looked at the driver this mor= ning. given that this is a multi-core box, I would lean towards a smaller napi_poll_weight, which unfortunately is a constant (64) in the code. 4 cores can take interrupts faster. (and I hate napi on routers) I have sometimes longed for an IQL (ingress queue limits) to also handle differences in packet size, dynamically changing the poll weight based on load - increasing it for loads with lots of small packets, decreasing it for lots of big packets. Furthermore this thing is doing software gro (up to 64 packets at a time) which is a LOT of processing at this layer in the stack. Its a two line patch to cut the weight to 16, but I have never managed to get a working build for this platform. > - Jonathan Morton > > > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel > --=20 Dave T=C3=A4ht worldwide bufferbloat report: http://www.dslreports.com/speedtest/results/bufferbloat And: What will it take to vastly improve wifi for everyone? https://plus.google.com/u/0/explore/makewififast