From owner-freebsd-current@FreeBSD.ORG Mon Mar 18 10:59:56 2013 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 97261255 for ; Mon, 18 Mar 2013 10:59:56 +0000 (UTC) (envelope-from tevans.uk@googlemail.com) Received: from mail-ie0-x22f.google.com (mail-ie0-x22f.google.com [IPv6:2607:f8b0:4001:c03::22f]) by mx1.freebsd.org (Postfix) with ESMTP id 6ED188F8 for ; Mon, 18 Mar 2013 10:59:56 +0000 (UTC) Received: by mail-ie0-f175.google.com with SMTP id c12so6655706ieb.20 for ; Mon, 18 Mar 2013 03:59:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=lWteIHcbZbLM/5Lhn2TVqMgWPxnjZ288oAJ/BEa61vs=; b=d4OCArSCHwctb3HErH6qo18cIUU7ZlntAt99qdAxQyaXyZZq+ijtfbrK+sNLn5neg8 8PYWSddI1RUimqukGohA0P7WQl5dEmB61YFM7xBGsyJYLO/qaJ9oBP0QxetzIMMKrPH1 EHtJlf/W0jbKgYUO/N8LMJODHSSM38hA/zzBnwqpzJu0Ogn9899TpVOZOUmFWQpjEM3A 0t7I3KMm0s+POAUm+8XAqc51guF2xQ3rRJPKqwi1L9Gn/dvPp/xPxQSi/CQrhyyMQCLD yg58GTHefZ/Wkg7vGXuwTS4gdoJ8xLSmTjT1FkS8yXFArPGczF9+4In78omPzYVlvu1R QrhQ== MIME-Version: 1.0 X-Received: by 10.50.135.105 with SMTP id pr9mr5766658igb.6.1363600903766; Mon, 18 Mar 2013 03:01:43 -0700 (PDT) Received: by 10.64.6.234 with HTTP; Mon, 18 Mar 2013 03:01:43 -0700 (PDT) In-Reply-To: References: Date: Mon, 18 Mar 2013 10:01:43 +0000 Message-ID: Subject: Re: FreeBSD is very slow when Memory chip sizes are imbalanced in slots From: Tom Evans To: Mehmet Erol Sanliturk Content-Type: text/plain; charset=UTF-8 Cc: freebsd-current X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Mar 2013 10:59:56 -0000 On Sun, Mar 17, 2013 at 8:26 PM, Mehmet Erol Sanliturk wrote: > Dear All , > > Previously , in the following message , I have mentioned effect of memory > chip placement on execution speed : > > http://lists.freebsd.org/pipermail/freebsd-current/2012-February/031836.html > Effect of Processor and Memory on KDE4 execution > speed These seems to be more than different memory slot allocation between those two boxes. Can you reproduce this on the one labelled 'FAST' by assigning memory in the same manner as it is assigned in the one labelled 'SLOW'? > > > The above thread did not produce any usable result . > > The problem is persisting over 9.1 and 10.0 current . > > My opinion is that , it is NOT related to KDE only . > > After X is started , any desktop is behaving very slowly . > This is also visible in PC-BSD and GhostBSD . This is very nebulous. What is 'very slowly'? Is there a test you can run that is independent of X, KDE, etc that demonstrates this? One thing that KDE does require (iirc - from about 5 years ago, probably wrong now) is that since KDE is C++, it spends a lot of time loading executables/libraries into memory and prelinking them. If you have dramatically lowered your RAM bandwidth, then this stage could take a lot longer. One thing that could cause memory bandwidth to lower is by installing mismatched modules. The BIOS will set all RAM up at the same speed, the lowest that all of the installed RAM supports. If you fill the RAM slots with mismatched modules of different sizes, it may also not enable dual channel memory, further reducing the RAM bandwidth. Because of this, I think it is a jump to go from "My computer runs slow when I put these bits of RAM in" to "FreeBSD always runs slow when there is mismatched RAM". If you find out what is slow on FreeBSD - eg RAM bandwidth - you can then test the same thing in Linux. If Linux shows the same slowdown from fast to slow, then I'm sorry, that's a hardware defect. If, on the other hand, Linux is just as fast in both configurations, then I'm sure a lot of people would be interested as to why. Cheers Tom