From owner-freebsd-net@FreeBSD.ORG  Sat Oct 11 22:21:33 2014
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
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 9D5C24F0;
 Sat, 11 Oct 2014 22:21:33 +0000 (UTC)
Received: from onelab2.iet.unipi.it (onelab2.iet.unipi.it [131.114.59.238])
 by mx1.freebsd.org (Postfix) with ESMTP id 56667EF6;
 Sat, 11 Oct 2014 22:21:32 +0000 (UTC)
Received: by onelab2.iet.unipi.it (Postfix, from userid 275)
 id BDE197300B; Sun, 12 Oct 2014 00:24:57 +0200 (CEST)
Date: Sun, 12 Oct 2014 00:24:57 +0200
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: Adrian Chadd <adrian@freebsd.org>
Subject: Re: individual queue blocking entire rx unit on ixgbe (Re: How do
 I balance bandwidth over several virtual NICs?)
Message-ID: <20141011222457.GA11694@onelab2.iet.unipi.it>
References: <CA+hQ2+hYY7AWE7jJWAg8uYER2LRSPz8TcVPuamsRBLj_WQyakw@mail.gmail.com>
 <CAJ-Vmo=xiZtKkQEV30Y_c7a6uWD6PbuqzmSSDG12J=w8Z45biA@mail.gmail.com>
 <20141001203223.GA12122@onelab2.iet.unipi.it>
 <CAJ-Vmom+DsDDa-1GgpUBps8=hMM_1c5auH5kKRiCxAs=w_Casg@mail.gmail.com>
 <20141001234926.GC13187@onelab2.iet.unipi.it>
 <CAJ-Vmo=6+zPhmmn=uEAX4V0MLqay8iN8yF2zeXYH5zFP6vHJwg@mail.gmail.com>
 <20141001235312.GA14593@onelab2.iet.unipi.it>
 <CAJ-VmokesukRXn1=9Rx0npJqYzUcTZ6=i+Y5OjRFXdQFEM_2HQ@mail.gmail.com>
 <CAJ-VmokbhQj2ThjVa3NwUgDfiDt5vqVXvuZWvar+G2X0kM8_tQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAJ-VmokbhQj2ThjVa3NwUgDfiDt5vqVXvuZWvar+G2X0kM8_tQ@mail.gmail.com>
User-Agent: Mutt/1.5.20 (2009-06-14)
Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>,
 Elof Ofel <elofu17@hotmail.com>,
 "Alexander V. Chernikov" <melifaro@freebsd.org>,
 Jack Vogel <jfvogel@gmail.com>
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 11 Oct 2014 22:21:33 -0000

On Sat, Oct 11, 2014 at 03:03:13PM -0700, Adrian Chadd wrote:
> Ping,
> 
> Luigi - would you mind sending through a diff ? I'd like to get this
> into -HEAD on both igb and ixgbe.


here it is.

As a result of this patch, ixgbe_rx_enable_drop() and the disable function
become useless and should be removed.
Probably the code (or the commit log) should also mention that the DROP_EN
bit is only read when the rx unit is started, this is why the code should
go here and not in the sysctl handler.

cheers
luigi

Index: ixgbe.c
===================================================================
--- ixgbe.c	(revision 272603)
+++ ixgbe.c	(working copy)
@@ -4377,6 +4377,19 @@
 		srrctl &= ~IXGBE_SRRCTL_BSIZEPKT_MASK;
 		srrctl |= bufsz;
 		srrctl |= IXGBE_SRRCTL_DESCTYPE_ADV_ONEBUF;
+		/*
+		 * Set DROP_EN iff we have no flow control and >1 queue.
+		 * Note that srrctl was cleared shortly before during reset,
+		 * so we do not need to clear the bit, but do it just in case
+		 * this code is moved elsewhere.
+		 */
+		if (adapter->num_queues > 1 &&
+		    adapter->hw.fc.requested_mode == ixgbe_fc_none) {
+			srrctl |= IXGBE_SRRCTL_DROP_EN;
+		} else {
+			srrctl &= ~IXGBE_SRRCTL_DROP_EN;
+		}
+
 		IXGBE_WRITE_REG(hw, IXGBE_SRRCTL(i), srrctl);
 
 		/* Setup the HW Rx Head and Tail Descriptor Pointers */