From owner-freebsd-net@FreeBSD.ORG Tue May 8 05:16:57 2012 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 0A7871065672; Tue, 8 May 2012 05:16:57 +0000 (UTC) (envelope-from jfvogel@gmail.com) Received: from mail-we0-f182.google.com (mail-we0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id 2F5A38FC14; Tue, 8 May 2012 05:16:56 +0000 (UTC) Received: by werg1 with SMTP id g1so975677wer.13 for ; Mon, 07 May 2012 22:16:55 -0700 (PDT) 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=EF+iP4PaNTIcZLZKGMRhcMbCo4W2Djv0l7uRLg4gkg0=; b=DMSwUDPxI+/QmANhM+6+lNQQTcFU7+4zP+V81VaJHgBx4up5G/lwzY06r96bkVl3A+ 8Qc/z8opExli0XXBtJ8v4iUrZuPOHRA6v3iQsZ8scY8DEqZrjYN7+z8bG5aWrPhHxnUn C90lx0m/DlAI4elH7+pY1/2Njxjc1aJYnGKCSisb+OUoKVpHnqEvSPOaoo1f3XbAMhB0 A3PJYeNewJBr4kZrXFEDgHVl2cmAwcLvlrYLV/OBE248osCmo6xQ6ZiLFA3RClTWpZcX ac5pmRsCM+fOHPAgWxO2dUG6FodjWe5sYMbkjTD7xsDBE/KK7k+ZYqjhmpsqFDqJlxAS /cQg== MIME-Version: 1.0 Received: by 10.216.140.222 with SMTP id e72mr128065wej.69.1336454215257; Mon, 07 May 2012 22:16:55 -0700 (PDT) Received: by 10.180.7.103 with HTTP; Mon, 7 May 2012 22:16:55 -0700 (PDT) In-Reply-To: References: Date: Mon, 7 May 2012 22:16:55 -0700 Message-ID: From: Jack Vogel To: Juli Mallett Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-net@freebsd.org, Vijay Singh Subject: Re: What does adapter->stats.mpc[] report for ixgbe? 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: Tue, 08 May 2012 05:16:57 -0000 Juli is correct, the FIFO is not partitioned by the driver queues as they exist in the current driver, its only seperated into the 3 parts I mentioned. Jack On Mon, May 7, 2012 at 9:55 PM, Juli Mallett wrote: > On Mon, May 7, 2012 at 9:42 PM, Vijay Singh wrote: > >> normal net traffic. But for now in FreeBSD its just one which is divided > >> into 3 parts: TX, RX, and FDIR (flow director). > > > > Jack, does the sw driver control in any way the partitioning of the > > FIFO? I guess enabling 2 hw queues splits the FIFO in half. But > > otherwise does the driver control this in any way? > > I don't believe that multiple queues splits the FIFO (Jack can correct > me if I'm wrong.) This is a small (very small) chunk of low-latency > memory on the NIC itself that is used to store the packets as they > come in off the wire before they are moved to a receive descriptor. > The driver does have a way of partitioning the space between transmit > and receive, look for "PBA" in the drivers. In some cases if you're > doing mostly-transmit or mostly-receive it can be very helpful to > tweak these values, but in the case where you're running out of > receive FIFO space constantly, it's (in my limited experience) more > likely to be a problem with bandwidth or latency between the NIC and > main memory, causing backpressure within the NIC as it tries to move > packets to receive buffers (which are the ones allocated in main, i.e. > host, memory.) >