From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3857BC433F5 for ; Tue, 3 May 2022 14:44:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237269AbiECOra (ORCPT ); Tue, 3 May 2022 10:47:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234369AbiECOr2 (ORCPT ); Tue, 3 May 2022 10:47:28 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AC21A38D80 for ; Tue, 3 May 2022 07:43:55 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6F2881042; Tue, 3 May 2022 07:43:55 -0700 (PDT) Received: from airbuntu (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D0EB43F774; Tue, 3 May 2022 07:43:53 -0700 (PDT) Date: Tue, 3 May 2022 15:43:52 +0100 From: Qais Yousef To: Xuewen Yan Cc: Xuewen Yan , dietmar.eggemann@arm.com, lukasz.luba@arm.com, rafael@kernel.org, viresh.kumar@linaro.org, mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, rostedt@goodmis.org, linux-kernel@vger.kernel.org, di.shen@unisoc.com Subject: Re: [PATCH] sched: Take thermal pressure into account when determine rt fits capacity Message-ID: <20220503144352.lxduzhl6jq6xdhw2@airbuntu> References: <20220420135127.o7ttm5tddwvwrp2a@airbuntu> <20220421161509.asz25zmh25eurgrk@airbuntu> <20220425161209.ydugtrs3b7gyy3kk@airbuntu> <20220426092142.lppfj5eqgt3d24nb@airbuntu> <20220427105844.otru4yohja4s23ye@wubuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Xuewen On 05/01/22 11:20, Xuewen Yan wrote: > Hi Qais > Thanks for the patient explanation.:) > And I have some other concerns. > > On Wed, Apr 27, 2022 at 6:58 PM Qais Yousef wrote: > > > > On 04/27/22 09:38, Xuewen Yan wrote: > > > > > > The best (simplest) way forward IMHO is to introduce a new function > > > > > > > > > > > > bool cpu_in_capacity_inversion(int cpu); > > Maybe the implementation of this function, I have not thought of a > good solution. > (1)how to define the inversion, if the cpu has two > cluster(little/big)，it is easy, but still need mark which is the big > cpu... I'd define it as: capacity_orig_of(cpu) - thermal_pressure(cpu) < capacity_orig_of(next_level_cpu) > (2)because the mainline kernel should be common, if the cpu has three > or more clusters, maybe the mid cpus also would be inversion; Yes. I pray this is highly unlikely though! We should cater for it still. > (3)what time update the cpu inversion state, if we judge the cpu > inversion whenever the thermal pressure changed, could we receive the > complexity? because may we should traverse all possible cpu. In my head, it would make sense to detect the inversion in update_cpu_capacity() OR in topology_update_thermal_pressure(). So at whatever rate this happens at. Does this answer your question? Basically I believe something like this should be enough (completely untested) --->8--- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a68482d66535..44c7c2598d87 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8399,16 +8399,37 @@ static unsigned long scale_rt_capacity(int cpu) static void update_cpu_capacity(struct sched_domain *sd, int cpu) { + unsigned long capacity_orig = arch_scale_cpu_capacity(cpu); unsigned long capacity = scale_rt_capacity(cpu); struct sched_group *sdg = sd->groups; + struct rq *rq = cpu_rq(cpu); - cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu); + rq->cpu_capacity_orig = capacity_orig; if (!capacity) capacity = 1; - cpu_rq(cpu)->cpu_capacity = capacity; - trace_sched_cpu_capacity_tp(cpu_rq(cpu)); + rq->cpu_capacity = capacity; + trace_sched_cpu_capacity_tp(rq); + + if (static_branch_unlikely(&sched_asym_cpucapacity)) { + unsigned long inv_cap = capacity_orig - thermal_load_avg(rq); + + rq->cpu_capacity_inverted = 0; + + for_each_possible_cpu(cpu) { + unsigned long cap = arch_scale_cpu_capacity(cpu); + + if (capacity_orig <= cap) + continue; + + if (cap > inv_cap) { + rq->cpu_capacity_inverted = inv_cap; + break; + } + } + + } sdg->sgc->capacity = capacity; sdg->sgc->min_capacity = capacity; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 8dccb34eb190..bfe84c870bf9 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -992,6 +992,7 @@ struct rq { unsigned long cpu_capacity; unsigned long cpu_capacity_orig; + unsigned long cpu_capacity_inverted; struct callback_head *balance_callback; @@ -2807,6 +2808,11 @@ static inline unsigned long capacity_orig_of(int cpu) return cpu_rq(cpu)->cpu_capacity_orig; } +static inline unsigned long cpu_in_capacity_inversion(int cpu) +{ + return cpu_rq(cpu)->cpu_capacity_inverted; +} + /** * enum cpu_util_type - CPU utilization type * @FREQUENCY_UTIL: Utilization used to select frequency --->8--- Thanks -- Qais Yousef