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Shutemov" , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Christopher Lameter , Vlastimil Babka Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Message-ID: <20200706160815.GH3448022@tassilo.jf.intel.com> References: <20200624092846.9194-4-srikar@linux.vnet.ibm.com> <20200701084200.GN2369@dhcp22.suse.cz> <20200701100442.GB17918@linux.vnet.ibm.com> <184102af-ecf2-c834-db46-173ab2e66f51@redhat.com> <20200701110145.GC17918@linux.vnet.ibm.com> <0468f965-8762-76a3-93de-3987cf859927@redhat.com> <12945273-d788-710d-e8d7-974966529c7d@redhat.com> <20200701122110.GT2369@dhcp22.suse.cz> <20200703091001.GJ21462@kitsune.suse.cz> <20200703092414.GR18446@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200703092414.GR18446@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > What's the point of this indirection other than another way of avoiding > > empty node 0? > > Honestly, I do not have any idea. I've traced it down to > Author: Andi Kleen > Date: Tue Jan 11 15:35:48 2005 -0800 I don't remember all the details, and I can't even find the commit (is it in linux-historic?). But AFAIK there's no guarantee PXMs are small and continuous, so it seemed better to have a clean zero based space. Back then we had a lot of problems with buggy SRAT tables in BIOS, so we really tried to avoid trusting the BIOS as much as possible. -Andi