From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 92F871381F3 for ; Sat, 15 Dec 2012 17:58:57 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id D3EE021C048; Sat, 15 Dec 2012 17:58:43 +0000 (UTC) Received: from mail-la0-f53.google.com (mail-la0-f53.google.com [209.85.215.53]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 51FA221C091 for ; Sat, 15 Dec 2012 17:56:46 +0000 (UTC) Received: by mail-la0-f53.google.com with SMTP id w12so3662582lag.40 for ; Sat, 15 Dec 2012 09:56:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:user-agent:in-reply-to :references:mime-version:content-transfer-encoding:content-type; bh=wrXnE2o0yPXvAZAbAxp9+dpbFeLjOCZgbpahGbGbW6A=; b=cEsp+MQEdqPk3+Y8DZJ1pupmqwtC1hbgHpUObwGielPHx6KMqcKOpxwIftAOFrXzFI 2pgEWsqfPHGQFXfD5NJPaAqcODGcxZW0yhFG6CxjAQAJFA511FDuDm/DJelZESfQAD5N xGPnmaCM8YCOJcYd4wxpcuqSCvgM4MfOFROb90fzThIZvUnWiWcEyCzb2ZikIqDs7ZT+ bt82/hRtqBxvCg3gu7ADakYlvdeYdED9DhJulA/nYeC1bJmUVvGAvpXqE9VvpQEZI+eK TlmrYVuhfDhNxFpUwDZShNmK4JJ1aq5S59cttCikltWZdllnyfsgI78xHWaTjTdo2mpa rr7g== Received: by 10.112.82.166 with SMTP id j6mr3816576lby.25.1355594204683; Sat, 15 Dec 2012 09:56:44 -0800 (PST) Received: from localhost.localnet (p4FC600C4.dip0.t-ipconnect.de. [79.198.0.196]) by mx.google.com with ESMTPS id ee5sm3077192lbb.14.2012.12.15.09.56.43 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 15 Dec 2012 09:56:44 -0800 (PST) From: Volker Armin Hemmann To: gentoo-user@lists.gentoo.org Cc: Grant Subject: Re: [gentoo-user] Dual or Quad CPU complications? Date: Sat, 15 Dec 2012 18:56:42 +0100 Message-ID: <2026398.C7IXBk4F5F@localhost> User-Agent: KMail/4.9.4 (Linux/3.4.20; KDE/4.9.4; x86_64; ; ) In-Reply-To: References: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Archives-Salt: 79060cbe-6c26-4d51-a5c4-dd2ca9a3ec3c X-Archives-Hash: 09bbff1c8229d884ea37ce3304e9c98f Am Freitag, 14. Dezember 2012, 01:44:26 schrieb Grant: > > > So if I have 2 physical CPU's with 4 cores each and I enable SMP, I'm > > using > > > > 8 cores? Can NUMA be either enabled or disabled when using more than > > one > > > > physical CPU, or is it required? > > > > NUMA is a hardware architecture. It's how you access memory on a > > hardware level: NUMA = Non Uniform Memory Access vs a UMA architecture > > of typical (old/legacy) SMP systems (UMA = Uniform Memory Access). > > > > In a UMA system, all the memory belongs to all the sockets. In a NUMA > > system, each socket has it's "own" local memory. In modern (x86-64) > > processors, each socket has it's own memory controller so each socket > > controls its own local memory. If one socket runs out of memory it can > > ask another socket to lend him some memory. In a UMA system, no socket > > has to ask since memory is global and belongs to all sockets so if one > > socket uses up all the memory ... the rest "starve". In NUMA, there's > > more control over who uses what (be it cores or RAM). > > > > If you have a modern dual or quad (or higher #) socket system ... > > you've got NUMA architecture and you can't get rid of it, it's > > hardware, not software. > > So I must enable CONFIG_NUMA for more than one physical CPU, and disable it > for only one physical CPU? you never need numa for one cpu. Ok? And even if you have several, you will probably never need it. -- #163933