From owner-freebsd-net@FreeBSD.ORG Mon Sep 23 05:34:27 2013 Return-Path: Delivered-To: net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 86AD75E0; Mon, 23 Sep 2013 05:34:27 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-wi0-x22a.google.com (mail-wi0-x22a.google.com [IPv6:2a00:1450:400c:c05::22a]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 7F52B2D69; Mon, 23 Sep 2013 05:34:26 +0000 (UTC) Received: by mail-wi0-f170.google.com with SMTP id cb5so1783896wib.1 for ; Sun, 22 Sep 2013 22:34:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=WLrObaRrjaudgHrsVVp7UTPOur5ytPU9agZs04Amk5Q=; b=GUI48D0a14dpnmlM+4thtySnazrxLS8QMebZL+zjfrMsxmKy1HOzQauSBn5NNQLWmI PtoJ+78lL+9ewqH/Kr/uW34rbahR3SDTtawk2Y8V6xRJgfwsapM+4jGrFiii2pA4l3So u5kivhOtxUdosaa+lNmz0KMcxiB2RJkYvoeaFhUulfsj9hyAzd2tk1N/Me/3nIONfkE5 XpptXkmG+l9E681dKG0H0dyoO1UeDzkdTe6fcimALMGDyLuJTRWp60bKvCJp8fGSKeaK 8VmaP+IdPQRUsjiiy4iIBbiZluGpsOEGzVAqvYf7ShbDBetKt5LKRNP8nevOvDZhPLPz FzGg== MIME-Version: 1.0 X-Received: by 10.180.9.45 with SMTP id w13mr12257051wia.0.1379914464878; Sun, 22 Sep 2013 22:34:24 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.216.73.133 with HTTP; Sun, 22 Sep 2013 22:34:24 -0700 (PDT) In-Reply-To: References: <521E41CB.30700@yandex-team.ru> <523F4F14.9090404@yandex-team.ru> Date: Sun, 22 Sep 2013 22:34:24 -0700 X-Google-Sender-Auth: ZD6q-sKKWSA9dbPfadU_9a8cm3I Message-ID: Subject: Re: Network stack changes From: Adrian Chadd To: Luigi Rizzo Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.14 Cc: "Alexander V. Chernikov" , Luigi Rizzo , Andre Oppermann , "Andrey V. Elsukov" , FreeBSD Net X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 23 Sep 2013 05:34:27 -0000 On 22 September 2013 21:52, Luigi Rizzo wrote: > locking affects scalability; but dxr and similar algorithms have much fewer > memory lookups, not to mention the huge memory footprint of > the freebsd radix tree code. > > Anyways i'd really encourage you to read the dxr paper, it is short > and hopefully can give you a better idea of the details (and with data > supporting them) than these short notes. > > I read the paper. :-) I believe it! It's not the first paper that I've read that packed a FIB into a sensibly cacheable structure. I'm just as interested however in making sure that we actually give people the tools to inspect this stuff for themselves, rather than all of us hacking up something from scratch every time we want to profile this kind of thing. The other side of this coin is locking, and the paper didn't go into that. Eliminating the radix tree overhead is great; now we just have to avoid grabbing all those locks all the damned time for each frame.. -adrian