From owner-freebsd-current@FreeBSD.ORG Sun Oct 8 12:45:39 2006 Return-Path: X-Original-To: current@freebsd.org Delivered-To: freebsd-current@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0A8D616A412 for ; Sun, 8 Oct 2006 12:45:39 +0000 (UTC) (envelope-from astrodog@gmail.com) Received: from wx-out-0506.google.com (wx-out-0506.google.com [66.249.82.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id DFD9D43D7D for ; Sun, 8 Oct 2006 12:45:19 +0000 (GMT) (envelope-from astrodog@gmail.com) Received: by wx-out-0506.google.com with SMTP id i27so1247097wxd for ; Sun, 08 Oct 2006 05:45:19 -0700 (PDT) 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=YWu+L8wZflRd3GUWVVocY73lcocphHgzaZJ+87+ZgnZthAKy6kIkQAEOkjrkiDacyoMkvlOVw85fANkAZy2dDqSyAu8tyHJ5URCABEg5JceUercfg9YqJqZ9gwjkXVl69zAfu3HUY6fASaEZ+YN6J6oHor1pAPcQMBTx7H2wzyk= Received: by 10.70.8.20 with SMTP id 20mr9116782wxh; Sun, 08 Oct 2006 05:45:19 -0700 (PDT) Received: by 10.70.118.3 with HTTP; Sun, 8 Oct 2006 05:45:19 -0700 (PDT) Message-ID: <2fd864e0610080545m1038d560o74767d775d0ad26b@mail.gmail.com> Date: Sun, 8 Oct 2006 07:45:19 -0500 From: Astrodog To: "LI Xin" In-Reply-To: <4528F069.7040504@delphij.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <2fd864e0610080423q7ba6bdeal656a223e662a5d@mail.gmail.com> <200610082011.53649.davidxu@freebsd.org> <2fd864e0610080516k6682c101i8d9b83578593fb28@mail.gmail.com> <4528F069.7040504@delphij.net> Cc: freebsd-current@freebsd.org, David Xu , current@freebsd.org Subject: Re: [PATCH] MAXCPU alterable in kernel config - needs testers X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 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: Sun, 08 Oct 2006 12:45:39 -0000 On 10/8/06, LI Xin wrote: > Astrodog wrote: > > On 10/8/06, David Xu wrote: > >> On Sunday 08 October 2006 19:23, Astrodog wrote: > >> > With the quad core processors coming out soon, this is going to become > >> > more of an issue.. (Sun T1/2000s aside). This is basically the same > >> > patch from a few months ago, with updated offsets. > >> > > >> > If you don't define MAXCPU in the kernel config, it reverts to old > >> > behavior. It has no logic to keep you from shooting yourself in the > >> > foot though.. you can define options SMP and options MAXCPU 128 on > >> > arm. > >> > > >> > --- Harrison Grundy > >> > >> I think MAXCPU should not be great than 32, since we currently define > >> cpumask_t as an integer which now should be changed to a bitmap and > >> a group of operations like we did for sigset_t. > >> > >> David Xu > >> > > > > Currently, MAXCPU is 16 on most platforms. > > In general, this value serves as a boundary of the kernel logic, and is > determined by various factors, e.g., the bits available in cpumask_t, > etc., therefore, I really do not see much benefit of letting this value > customizable. > > Perhaps we can say that the problem is not that the value itself is > immutable by the system administrator, but it was (perhaps?) not > correctly reflected the actual support that the kernel can provide? > Perhaps the way to handle this, then, is to only allow it to be set lower. --- Harrison