From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759384AbYG1Smb (ORCPT ); Mon, 28 Jul 2008 14:42:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754256AbYG1SmY (ORCPT ); Mon, 28 Jul 2008 14:42:24 -0400 Received: from relay1.sgi.com ([192.48.171.29]:38777 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753511AbYG1SmX (ORCPT ); Mon, 28 Jul 2008 14:42:23 -0400 Message-ID: <488E130E.9060108@sgi.com> Date: Mon, 28 Jul 2008 11:42:22 -0700 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Ingo Molnar CC: Linus Torvalds , Linux Kernel Mailing List , Andrew Morton , Rusty Russell Subject: Re: [git pull] cpus4096 fixes References: <20080727190601.GA764@elte.hu> <20080727210350.GA30033@elte.hu> In-Reply-To: <20080727210350.GA30033@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: ... > NUMA-locality might have been a valid argument in favor of the massive > array of constant cpumasks (common usage is to use it for the current > cpu), if it wasnt all stupidly allocated on the boot node: > > cpumask_of_cpu_map = alloc_bootmem_low(sizeof(cpumask_t) * nr_cpu_ids); > for (i = 0; i < nr_cpu_ids; i++) > cpu_set(i, cpumask_of_cpu_map[i]); The alternate method was for each cpu to contribute a cpumask_of_cpu for itself in the percpu area. I don't recall why that idea was rejected. But yes, the set_cpus_allowed is the biggest receiver of cpumask_t's with a single bit set. I had also proposed a different interface allowing just that, but I think it was rejected as being redundant. Thanks, Mike