From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: intermittant petabyte usage reported with broadcom nic Date: 13 Apr 2007 03:15:59 +0200 Message-ID: References: <20070402014319.GA8345@zip.com.au> <20070402001300.3b66007d.akpm@linux-foundation.org> <20070412225249.GU8345@zip.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: CaT , Michael Chan , Andrew Morton , linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Roland Dreier Return-path: Received: from cantor2.suse.de ([195.135.220.15]:59553 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753932AbXDMARs (ORCPT ); Thu, 12 Apr 2007 20:17:48 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Roland Dreier writes: > [Adding Michael Chan, who seems to look after bnx2, to the cc list] > > > To clarify it's an Intel Dual Core Xeon (I just wound up as thinking of > > them all as amd64s). Network card driver in use is the one defined by > > CONFIG_BNX2. Kernel's monolithic. > > From a quick look at bnx2.c, it seems that the driver gives the NIC > (firmware?) a block of memory to DMA stats into, and just reads from > that memory in its get_stats method. So if you're seeing wonky stats > from the NIC intermittently, my best guess would be that firmware is > occasionally writing junk into the stats block. When only the firmware is writing to that area it could be put into an own page and then write protected with change_page_attr() That would catch any corruption coming from the rest of the kernel. -Andi