Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764856AbYARUz1 (ORCPT ); Fri, 18 Jan 2008 15:55:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759664AbYARUzR (ORCPT ); Fri, 18 Jan 2008 15:55:17 -0500 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:37752 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757303AbYARUzQ (ORCPT ); Fri, 18 Jan 2008 15:55:16 -0500 Message-ID: <4791122E.8070205@sgi.com> Date: Fri, 18 Jan 2008 12:55:10 -0800 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Ingo Molnar CC: Ingo Oeser , Andrew Morton , Andi Kleen , Christoph Lameter , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/5] x86: Add config variables for SMP_MAX References: <20080118183011.354965000@sgi.com> <20080118183011.917801000@sgi.com> <200801182104.22486.ioe-lkml@rameria.de> <479108C3.1010800@sgi.com> <20080118204845.GD3079@elte.hu> In-Reply-To: <20080118204845.GD3079@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 Content-Length: 2380 Lines: 65 Ingo Molnar wrote: > * Mike Travis wrote: > >>>> +config THREAD_ORDER >>>> + int "Kernel stack size (in page order)" >>>> + range 1 3 >>>> + depends on X86_64_SMP >>>> + default "3" if X86_SMP_MAX >>>> + default "1" >>>> + help >>>> + Increases kernel stack size. >>>> + >>> Could you please elaborate, why this is needed and put more info >>> about this requirement into this patch description? >>> >>> People worked hard to push data allocation from stack to heap to >>> make THREAD_ORDER of 0 and 1 possible. So why increase it again and >>> why does this help scalability? >>> >>> Many thanks and Best Regards >>> >>> Ingo Oeser, puzzled a bit :-) >> >> The primary problem arises because of cpumask_t local variables. >> Until I can deal with these, increasing NR_CPUS to a really large >> value increases stack size dramatically. > > those should be fixed: > >> Here are the top stack consumers with NR_CPUS = 4k. >> >> 16392 isolated_cpu_setup >> 10328 build_sched_domains >> 8248 numa_initmem_init >> 4664 cpu_attach_domain >> 4104 show_shared_cpu_map >> 3656 centrino_target >> 3608 powernowk8_cpu_init >> 3192 sched_domain_node_span >> 3144 acpi_cpufreq_target >> 2584 __svc_create_thread >> 2568 cpu_idle_wait >> 2136 netxen_nic_flash_print >> 2104 powernowk8_target >> 2088 _cpu_down >> 2072 cache_add_dev >> 2056 get_cur_freq >> 0 acpi_processor_ffh_cstate_probe >> 2056 microcode_write >> 0 acpi_processor_get_throttling >> 2048 check_supported_cpu > > (and most of that is performance-uncritical.) > > Ingo How big is the stack during early startup? Thanks, Mike -- 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/