From owner-freebsd-net@FreeBSD.ORG Tue Jan 20 12:14:53 2004 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 679D616A4CE for ; Tue, 20 Jan 2004 12:14:53 -0800 (PST) Received: from mail.sandvine.com (sandvine.com [199.243.201.138]) by mx1.FreeBSD.org (Postfix) with ESMTP id AF07743D48 for ; Tue, 20 Jan 2004 12:14:51 -0800 (PST) (envelope-from gnagelhout@sandvine.com) Received: by mail.sandvine.com with Internet Mail Service (5.5.2657.72) id ; Tue, 20 Jan 2004 14:59:44 -0500 Message-ID: From: Gerrit Nagelhout To: freebsd-net@freebsd.org Date: Tue, 20 Jan 2004 14:59:36 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2657.72) Content-Type: text/plain; charset="iso-8859-1" Subject: Intel em transmit hangs with DMA packet prefetching enabled X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 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, 20 Jan 2004 20:14:53 -0000 Hi, Recently I turned on the packet prefetching feature (register TXDMAC 0x3000, set DPP to 0). This increases the maximum transmit performance per port by about 50KPPS. Everything worked fine, until one of our applications that sends lots of data with multiple (2 - 3) mbufs per descriptor started using this feature, and the transmitter started hanging. The watchdog feature in the driver catches it, and resets the chip, after which everything is good again for a while. Has anyone else seen this behaviour before? Thanks, Gerrit Nagelhout