Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755427AbWKNGYb (ORCPT ); Tue, 14 Nov 2006 01:24:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755428AbWKNGYb (ORCPT ); Tue, 14 Nov 2006 01:24:31 -0500 Received: from nf-out-0910.google.com ([64.233.182.184]:40956 "EHLO nf-out-0910.google.com") by vger.kernel.org with ESMTP id S1755427AbWKNGYb (ORCPT ); Tue, 14 Nov 2006 01:24:31 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=krL4Umr9M6EBQHY7pmUSwIXwmSS+3qjQmoG57KtNbqUOwxCVf7GZ1mPFqGReGfyGF5fIPFj5vf2gAY/Q9aD61ojK+NhVz6hJ0LuyNk9uXM4h20OTJa42MdFsYuDh1QjhGW3SRApIuF1ImttP+xa1osaPW3JTN4uNzBi3QjEZDL8= Message-ID: <787b0d920611132224n76cb2345t685bb5c521cedcbc@mail.gmail.com> Date: Tue, 14 Nov 2006 01:24:29 -0500 From: "Albert Cahalan" To: "Mikulas Patocka" Subject: Re: 2048 CPUs [was: Re: New filesystem for Linux] Cc: "Pavel Machek" , linux-kernel@vger.kernel.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <787b0d920611041154l69db46abv4c8c467809ada57c@mail.gmail.com> <20061107212614.GA6730@ucw.cz> <20061107231456.GB7796@elf.ucw.cz> <20061110090303.GB3196@elf.ucw.cz> <20061112142813.GA4371@ucw.cz> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 946 Lines: 24 > >> No intel document guarantees you that if more CPUs > >> simultaneously execute locked cmpxchg in a loop that a > > > > If we are talking 2048 cpus, we are talking ia64. > > IA64 spinlock is locked cmpxchg, if failed than pause (i386 equivalent of > rep nop) read the value, and if unlocked, try cmpxchg again. > > There is no fairness in it. I suppose we could use something better. There is the MCS lock, the related CLH lock, and IBM's improvement on the MCS lock. As with RCU, we'd need to get IBM's permission to use their lock. (so, how did we get permission for RCU?) The basic MCS lock is also patented I think. http://www.cs.rochester.edu/~scott/professional/Dijkstra/presentation.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/