From patchwork Thu Sep 7 10:41:09 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dietmar Eggemann X-Patchwork-Id: 9942113 X-Patchwork-Delegate: horms@verge.net.au Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5E63B6035F for ; Thu, 7 Sep 2017 10:41:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2F74827FB0 for ; Thu, 7 Sep 2017 10:41:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 246AF28249; Thu, 7 Sep 2017 10:41:15 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3EDA727FB0 for ; Thu, 7 Sep 2017 10:41:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754048AbdIGKlO (ORCPT ); Thu, 7 Sep 2017 06:41:14 -0400 Received: from foss.arm.com ([217.140.101.70]:58354 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753927AbdIGKlM (ORCPT ); Thu, 7 Sep 2017 06:41:12 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 270FA13D5; Thu, 7 Sep 2017 03:41:12 -0700 (PDT) Received: from [10.1.210.41] (e107985-lin.cambridge.arm.com [10.1.210.41]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 320833F540; Thu, 7 Sep 2017 03:41:10 -0700 (PDT) Subject: Re: [PATCH 1/4] arm: topology: remove cpu_efficiency To: Vincent Guittot Cc: linux-kernel , LAK , "devicetree@vger.kernel.org" , linux-samsung-soc , linux-renesas-soc@vger.kernel.org, Russell King , Rob Herring , Mark Rutland , Kukjin Kim , Krzysztof Kozlowski , Juri Lelli References: <20170830144120.9312-1-dietmar.eggemann@arm.com> <20170830144120.9312-2-dietmar.eggemann@arm.com> <303d3f7b-5d64-e13a-c4f9-dd575958cafa@arm.com> From: Dietmar Eggemann Message-ID: Date: Thu, 7 Sep 2017 11:41:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 06/09/17 13:40, Vincent Guittot wrote: > On 6 September 2017 at 13:43, Dietmar Eggemann wrote: >> Hi Vincent, >> >> On 04/09/17 08:49, Vincent Guittot wrote: >>> Hi Dietmar, >>> >>> Removing cpu effificiency table looks good to me. Nevertheless, i have >>> some comments below for this patch. >> >> Thanks for the review! >> >>> On 30 August 2017 at 16:41, Dietmar Eggemann wrote: [...] I fixed the issue with the continue statement. Moreover, I think we should also remove the comment block about 'cpu capacity scale management' and 'cpu capacity table' on top of parse_dt_topology() because this is now all handled in drivers/base/arch_topology.c. -- >8 -- From: Dietmar Eggemann Date: Sun, 9 Jul 2017 23:43:43 +0100 Subject: [PATCH] arm: topology: remove cpu_efficiency Remove the 'cpu_efficiency/clock-frequency dt property' based solution to set cpu capacity which was only working for Cortex-A15/A7 arm big.LITTLE systems. I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is shared between arm and arm64 and works for every big.LITTLE system no matter which core types it consists of. Cc: Russell King Cc: Vincent Guittot Cc: Juri Lelli Signed-off-by: Dietmar Eggemann --- arch/arm/kernel/topology.c | 130 ++------------------------------------------- 1 file changed, 3 insertions(+), 127 deletions(-) diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index bf949a763dbe..5f46d290e34b 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -30,69 +30,11 @@ #include #include -/* - * cpu capacity scale management - */ - -/* - * cpu capacity table - * This per cpu data structure describes the relative capacity of each core. - * On a heteregenous system, cores don't have the same computation capacity - * and we reflect that difference in the cpu_capacity field so the scheduler - * can take this difference into account during load balance. A per cpu - * structure is preferred because each CPU updates its own cpu_capacity field - * during the load balance except for idle cores. One idle core is selected - * to run the rebalance_domains for all idle cores and the cpu_capacity can be - * updated during this sequence. - */ - #ifdef CONFIG_OF -struct cpu_efficiency { - const char *compatible; - unsigned long efficiency; -}; - -/* - * Table of relative efficiency of each processors - * The efficiency value must fit in 20bit and the final - * cpu_scale value must be in the range - * 0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2 - * in order to return at most 1 when DIV_ROUND_CLOSEST - * is used to compute the capacity of a CPU. - * Processors that are not defined in the table, - * use the default SCHED_CAPACITY_SCALE value for cpu_scale. - */ -static const struct cpu_efficiency table_efficiency[] = { - {"arm,cortex-a15", 3891}, - {"arm,cortex-a7", 2048}, - {NULL, }, -}; - -static unsigned long *__cpu_capacity; -#define cpu_capacity(cpu) __cpu_capacity[cpu] - -static unsigned long middle_capacity = 1; -static bool cap_from_dt = true; - -/* - * Iterate all CPUs' descriptor in DT and compute the efficiency - * (as per table_efficiency). Also calculate a middle efficiency - * as close as possible to (max{eff_i} - min{eff_i}) / 2 - * This is later used to scale the cpu_capacity field such that an - * 'average' CPU is of middle capacity. Also see the comments near - * table_efficiency[] and update_cpu_capacity(). - */ static void __init parse_dt_topology(void) { - const struct cpu_efficiency *cpu_eff; - struct device_node *cn = NULL; - unsigned long min_capacity = ULONG_MAX; - unsigned long max_capacity = 0; - unsigned long capacity = 0; - int cpu = 0; - - __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity), - GFP_NOWAIT); + struct device_node *cn; + int cpu; cn = of_find_node_by_path("/cpus"); if (!cn) { @@ -101,9 +43,6 @@ static void __init parse_dt_topology(void) } for_each_possible_cpu(cpu) { - const u32 *rate; - int len; - /* too early to use cpu->of_node */ cn = of_get_cpu_node(cpu, NULL); if (!cn) { @@ -113,75 +52,14 @@ static void __init parse_dt_topology(void) if (topology_parse_cpu_capacity(cn, cpu)) { of_node_put(cn); - continue; } - - cap_from_dt = false; - - for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++) - if (of_device_is_compatible(cn, cpu_eff->compatible)) - break; - - if (cpu_eff->compatible == NULL) - continue; - - rate = of_get_property(cn, "clock-frequency", &len); - if (!rate || len != 4) { - pr_err("%s missing clock-frequency property\n", - cn->full_name); - continue; - } - - capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency; - - /* Save min capacity of the system */ - if (capacity < min_capacity) - min_capacity = capacity; - - /* Save max capacity of the system */ - if (capacity > max_capacity) - max_capacity = capacity; - - cpu_capacity(cpu) = capacity; } - /* If min and max capacities are equals, we bypass the update of the - * cpu_scale because all CPUs have the same capacity. Otherwise, we - * compute a middle_capacity factor that will ensure that the capacity - * of an 'average' CPU of the system will be as close as possible to - * SCHED_CAPACITY_SCALE, which is the default value, but with the - * constraint explained near table_efficiency[]. - */ - if (4*max_capacity < (3*(max_capacity + min_capacity))) - middle_capacity = (min_capacity + max_capacity) - >> (SCHED_CAPACITY_SHIFT+1); - else - middle_capacity = ((max_capacity / 3) - >> (SCHED_CAPACITY_SHIFT-1)) + 1; - - if (cap_from_dt) - topology_normalize_cpu_scale(); -} - -/* - * Look for a customed capacity of a CPU in the cpu_capacity table during the - * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the - * function returns directly for SMP system. - */ -static void update_cpu_capacity(unsigned int cpu) -{ - if (!cpu_capacity(cpu) || cap_from_dt) - return; - - topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity); - - pr_info("CPU%u: update cpu_capacity %lu\n", - cpu, topology_get_cpu_scale(NULL, cpu)); + topology_normalize_cpu_scale(); } #else static inline void parse_dt_topology(void) {} -static inline void update_cpu_capacity(unsigned int cpuid) {} #endif /* @@ -277,8 +155,6 @@ void store_cpu_topology(unsigned int cpuid) update_siblings_masks(cpuid); - update_cpu_capacity(cpuid); - pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n", cpuid, cpu_topology[cpuid].thread_id, cpu_topology[cpuid].core_id,