From owner-freebsd-questions@FreeBSD.ORG Mon Sep 5 01:11:46 2011 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9B6EF1065670 for ; Mon, 5 Sep 2011 01:11:46 +0000 (UTC) (envelope-from brett@lariat.net) Received: from lariat.net (lariat.net [66.119.58.2]) by mx1.freebsd.org (Postfix) with ESMTP id 1CC068FC12 for ; Mon, 5 Sep 2011 01:11:45 +0000 (UTC) Received: from WildRover.lariat.net (IDENT:ppp1000.lariat.net@lariat.net [66.119.58.2]) by lariat.net (8.9.3/8.9.3) with ESMTP id TAA07025; Sun, 4 Sep 2011 19:11:30 -0600 (MDT) Message-Id: <201109050111.TAA07025@lariat.net> X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9 Date: Sun, 04 Sep 2011 19:11:30 -0600 To: Robert Bonomi From: Brett Glass In-Reply-To: <201109042333.p84NXkiK002887@mail.r-bonomi.com> References: <201109041814.MAA04568@lariat.net> <201109042333.p84NXkiK002887@mail.r-bonomi.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Cc: questions@freebsd.org Subject: Re: Huge interrupt overhead reported after RAM added to Atom-based system X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Sep 2011 01:11:46 -0000 At 05:33 PM 9/4/2011, Robert Bonomi wrote: >Does sound sorta-like VM thrashing. > >Could it be hardware based _bank-switching_ on memory? > >This would cause an intterrupt every time successive memory accesses were in >differnt 'banks'. Indeed. In fact, when you put in a 4GB module, the BIOS reports that you have 1GB of "4GB+ memory" (a possible indication that the last gigabyte is mapped into some special space). Maybe there's something like PAE going on. Anyone know what might be up? (Copying this message back to the list thread) --Brett Glass