From owner-freebsd-net@FreeBSD.ORG Wed Dec 26 21:08:58 2007 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CEAA516A418 for ; Wed, 26 Dec 2007 21:08:58 +0000 (UTC) (envelope-from jfvogel@gmail.com) Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.158]) by mx1.freebsd.org (Postfix) with ESMTP id 66ED213C44B for ; Wed, 26 Dec 2007 21:08:58 +0000 (UTC) (envelope-from jfvogel@gmail.com) Received: by fg-out-1718.google.com with SMTP id 16so1846702fgg.35 for ; Wed, 26 Dec 2007 13:08:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=D7RlBniS6Jtn/1wRHqxBoQxcX7BcbUwLvy744DuB2T0=; b=GcTpd3ldUwTryAbrl038YIf2qAukVRlFfm2DL3RHb/b/Kf04AP1iH6rwmhoqokBLf9QArbbeL4kzzyMwbbH9IexPjiLtGJgA8rlHbFnHe2I+1lbp+WJ1JlfUObmb97YPdc1v8fAG3hpT7Yxrv2Oi27ciAWkJki7e5g3Qu4k4kUk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=oVvJSOvFo55heG8R3Lx2bi4IwUEf8rt/7ERmNQYMTtTzjc5jwZXQuhUG4dkoJUX8NbPe0pqGRULEm5vTKs1q0hc5wU4IZG5eUIS90EszfwOGem734vv2PiIr1Pi+FtFGI4r0Iur+U1ovwulXjNQedXW7dJ78GqKDMrRDzVzkIek= Received: by 10.86.84.5 with SMTP id h5mr7045465fgb.75.1198703337058; Wed, 26 Dec 2007 13:08:57 -0800 (PST) Received: by 10.86.97.10 with HTTP; Wed, 26 Dec 2007 13:08:57 -0800 (PST) Message-ID: <2a41acea0712261308y7ac8d831i4e02c7849bbca3f6@mail.gmail.com> Date: Wed, 26 Dec 2007 13:08:57 -0800 From: "Jack Vogel" To: "Nash Nipples" In-Reply-To: <508610.85778.qm@web36309.mail.mud.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <508610.85778.qm@web36309.mail.mud.yahoo.com> Cc: freebsd-net@freebsd.org Subject: Re: Maximum NIC interrupts X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Dec 2007 21:08:58 -0000 On Dec 26, 2007 8:10 AM, Nash Nipples wrote: > Dear Jordi, > > In theory, on a Gigabit link you get 1 000 000 000 bits * second. > By default you have the MTU set to 1500 bytes which makes ~12 000 bits. > 1 000 000 000 / 12 000 = ~ 83 333 packets per second. > 83 333 packets per second makes 0.083333 packets per microsecond. > 1 / 0.08333 = 12.0 microseconds per packet. Thus one can interrupt CPU > at a rate of ~83 333 times per second. If you use lower packets sizes you > might get even more funny numbers. > > 8000 is a quiet low number. The driver was developed by guys > at Intel. I don't see a reason to worry. > > By the way they have products with Interrupt Moderation. > http://www.intel.com/design/network/applnots/ap450.htm Yes, one of the items in my queue is AIM, adaptive interrupt moderation, the Linux driver has this, my coworker Jesse Brandeburg developed that code, and I hope to do something similar for the em driver. Anyway, I'm still on vacation and don't want to distract myself from music, but look for AIM sometime this new year :) Jack