From owner-freebsd-net@FreeBSD.ORG Wed Feb 11 02:49:33 2015 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id B65BA893; Wed, 11 Feb 2015 02:49:33 +0000 (UTC) Received: from mail-la0-f51.google.com (mail-la0-f51.google.com [209.85.215.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 6953392; Wed, 11 Feb 2015 02:49:33 +0000 (UTC) Received: by labgd6 with SMTP id gd6so750486lab.7; Tue, 10 Feb 2015 18:49:31 -0800 (PST) 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; bh=OnYKG5dBYACjjjIphUAp3YVQHKJvWGKy2PpKNcerNlk=; b=T3UYKsKmxOqPtqoh2n1fVpzXqqRV8bDJwXa9fpimOZCe6UV+p8ref4bYrzrdpvwar6 XhTrow+bTHKdi5wmyCENkzBwNjOfLoeDn6vvkhMsIRMgEaXl30DIRHzabSmn02nZvpG6 vCp6JuB++ytzyPybCDI3+ikt5Aji9mWEfej649MdsAy/t8duOsthNcgdkLfgvIQM20em Hm4ZH4Nim7/SLVOEesWNB+iVdHHQmKwPdJOq8bceWTxp+sKs5Si0IsENIgOklMruclx5 S+V3Ow/SWNIoIIbpDJxCvStYvldc+dZ7GGFRPLR6H16BLCIwkpe+EBlMw0gKDQhaiaxl sGhA== MIME-Version: 1.0 X-Received: by 10.112.27.231 with SMTP id w7mr12481140lbg.49.1423622971215; Tue, 10 Feb 2015 18:49:31 -0800 (PST) Received: by 10.25.83.203 with HTTP; Tue, 10 Feb 2015 18:49:31 -0800 (PST) In-Reply-To: <54CBF396.3090903@ignoranthack.me> References: <54CBF396.3090903@ignoranthack.me> Date: Wed, 11 Feb 2015 10:49:31 +0800 Message-ID: Subject: Re: Intel 82574L (em) From: Sepherosa Ziehau To: Sean Bruno Content-Type: text/plain; charset=UTF-8 Cc: "freebsd-net@freebsd.org" 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: Wed, 11 Feb 2015 02:49:33 -0000 On Sat, Jan 31, 2015 at 5:11 AM, Sean Bruno wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > http://www.intel.com/content/dam/doc/datasheet/82574l-gbe-controller-datasheet.pdf > > According to 7.1.11, this device does indeed have 2 queues for stuff and > or things. So, basic RSS would be possible in something like an Atom box. > > I note that the em(4) driver intentionally disables this on > initialization. I'm up for some science on my new shiny, soon to be > router box. Any reason not to default to 1 queue and allow loader.conf > to raise it to 2? You could actually enable 2 RX rings w/o MSI-X on 82574; you still get the benefit of hardware calculated RSS hash at least. And as far as I have tested, 2 RX rings work for 82574L, but 2 TX rings don't work (gave me TX watchdog timeout). And you could also use 2 RX rings on 82571/82572/82573 and i217/i218; 2 TX rings work on 82571 at least (you need to setup TX context for each TX descriptor though). Best Regards, sephe