From owner-freebsd-net@FreeBSD.ORG Tue Jan 27 20:28:41 2015 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 450D8585 for ; Tue, 27 Jan 2015 20:28:41 +0000 (UTC) Received: from mail-we0-x22a.google.com (mail-we0-x22a.google.com [IPv6:2a00:1450:400c:c03::22a]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id D04005F2 for ; Tue, 27 Jan 2015 20:28:40 +0000 (UTC) Received: by mail-we0-f170.google.com with SMTP id w55so11608474wes.1 for ; Tue, 27 Jan 2015 12:28:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=XUoEfOqDFbfwJ2RerLlAbMnv0hOCYTueqJpLo7NH+7A=; b=H3IS0vRpHOo1UvJysYe50yqJP5vaAu7jO3OEAuQwduFpOOfLodVGfsQuE8QVs1J4ir EvOFPugk3q3/78cVqvsXh0aLtesDS0abMiGNsikx/8lGYm8eY2GQ5aWGs5lCKk6gkxlV hI03F8R+/5LJSIj0xS9byOhlMdTMhCIOY6cyuXXXo9/LebDTYJ3zprgV+Ar1g+Dr3ON/ VJg2SC8PhPWeR7ffs851blTTwgu4m7ncvbLez2k509XaO6tSoqi/ESF3ScOMOWel8cpE tLMWJ1JfppkmCMnIdO8k8bi0Md+PODYMy7YUodGqDCNDJHBWZRgtFv5415QiAWLbjpzr dFag== X-Received: by 10.194.192.98 with SMTP id hf2mr6736681wjc.52.1422390519260; Tue, 27 Jan 2015 12:28:39 -0800 (PST) MIME-Version: 1.0 Sender: cochard@gmail.com Received: by 10.194.61.1 with HTTP; Tue, 27 Jan 2015 12:28:19 -0800 (PST) In-Reply-To: References: <871tmgceup.fsf@marcos.anarc.at> <87vbjsaxxy.fsf@marcos.anarc.at> From: =?ISO-8859-1?Q?Olivier_Cochard=2DLabb=E9?= Date: Tue, 27 Jan 2015 21:28:19 +0100 X-Google-Sender-Auth: M0Rg9GiKyAHLPlqyNdgkwjsTP2Y Message-ID: Subject: Re: is polling still a thing? To: Michael Sierchio Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: "freebsd-net@freebsd.org" , Jim Thompson , =?ISO-8859-1?Q?Antoine_Beaupr=E9?= X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 Jan 2015 20:28:41 -0000 On Tue, Jan 27, 2015 at 9:15 PM, Michael Sierchio wrote: > > > On small, embedded computers running ipfw w/kernel nat and device polling > enabled (on em ether adapters), I observed the *reported* system load grow > very high. When disabling polling on the interfaces, it went back to > something normal. > > My impression is that the consensus among the core developers concerned > with networking is that device polling is an ancient hack and is > deprecated. In the case of a DDoS attack, there may be many other things to > try - at the infrastructure level - traffic diversion techniques like BGP > flowspec, use anycast, etc. On the individual server level, use stateful > rules with GRED enabled, dropping most new tcp or udp traffic based on load. > > > If I remember well, Luigi had a surprise regarding the advantage of using polling inside a VM: https://lists.freebsd.org/pipermail/freebsd-net/2013-May/035626.html But on real hardware, since the introduction of interrupt moderation on NIC, polling is not more useful.