Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751216AbWBJKFc (ORCPT ); Fri, 10 Feb 2006 05:05:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751217AbWBJKFc (ORCPT ); Fri, 10 Feb 2006 05:05:32 -0500 Received: from mtagate2.de.ibm.com ([195.212.29.151]:15392 "EHLO mtagate2.de.ibm.com") by vger.kernel.org with ESMTP id S1751216AbWBJKFc (ORCPT ); Fri, 10 Feb 2006 05:05:32 -0500 Date: Fri, 10 Feb 2006 11:05:21 +0100 From: Heiko Carstens To: Andi Kleen Cc: Nathan Lynch , Andrew Morton , Eric Dumazet , riel@redhat.com, linux-kernel@vger.kernel.org, torvalds@osdl.org, mingo@elte.hu, 76306.1226@compuserve.com, wli@holomorphy.com, Paul Jackson Subject: Re: [PATCH] percpu data: only iterate over possible CPUs Message-ID: <20060210100521.GA9307@osiris.boeblingen.de.ibm.com> References: <200602051959.k15JxoHK001630@hera.kernel.org> <20060208190512.5ebcdfbe.akpm@osdl.org> <20060208190839.63c57a96.akpm@osdl.org> <43EAC6BE.2060807@cosmosbay.com> <20060208204502.12513ae5.akpm@osdl.org> <20060209160808.GL18730@localhost.localdomain> <20060209161331.GE20554@osiris.boeblingen.de.ibm.com> <20060209173726.GA39278@muc.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060209173726.GA39278@muc.de> User-Agent: mutt-ng/devel (Linux) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1156 Lines: 23 > > > powerpc/ppc64, for instance, determines the number of possible cpus > > > from information exported by firmware (and I'm mystified as to why > > > other platforms don't do this). So it's typical to have a kernel an a > > > pSeries partition with NR_CPUS=128, but cpu_possible_map = 0xff. > > > > Simply because there is no such interface on s390. The only thing we know > > for sure is that if we are running under z/VM the user is free to > > configure up to 63 additional virtual cpus on the fly... > > x86-64 had the same problem, but we now require that you > boot with additional_cpus=... for how many you want. Default is 0 > (used to be half available CPUs but that lead to confusion) So introducing the additional_cpus kernel parameter seems to be the way to go (for XEN probably too). Even though it seems to be a bit odd if the user specifies both maxcpus=... and additional_cpus=... Heiko - 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/