From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 121EA11703 for ; Mon, 21 Aug 2023 19:57:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8890CC433C7; Mon, 21 Aug 2023 19:57:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1692647872; bh=QuVwe4HWWFYbRCmGpAVCPER6VuIYSk0TTi2aujkJaoQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mInGgvXsuYAPJ59rigOAeFg4yHc8ks6ZNviQ8cUan37t/hSK1Y4pvyqbBuOpf2Svy 15FqfsT+Yxbwom5Am7mp9Hi9MRbfZcaKsZxDhUqvFEeo+LFPvLg1Fh6YAlBRAXar9L xmGoBwjHWYKT57pw8NJyNEneS2D6dvVGofjPtH5c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vincent Guittot , "Peter Zijlstra (Intel)" , "Qais Yousef (Google)" Subject: [PATCH 6.1 169/194] sched/fair: Remove capacity inversion detection Date: Mon, 21 Aug 2023 21:42:28 +0200 Message-ID: <20230821194130.123737849@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230821194122.695845670@linuxfoundation.org> References: <20230821194122.695845670@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Vincent Guittot commit a2e90611b9f425adbbfcdaa5b5e49958ddf6f61b upstream. Remove the capacity inversion detection which is now handled by util_fits_cpu() returning -1 when we need to continue to look for a potential CPU with better performance. This ends up almost reverting patches below except for some comments: commit da07d2f9c153 ("sched/fair: Fixes for capacity inversion detection") commit aa69c36f31aa ("sched/fair: Consider capacity inversion in util_fits_cpu()") commit 44c7b80bffc3 ("sched/fair: Detect capacity inversion") Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20230201143628.270912-3-vincent.guittot@linaro.org Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/sched/fair.c | 84 +++------------------------------------------------ kernel/sched/sched.h | 19 ----------- 2 files changed, 5 insertions(+), 98 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4464,17 +4464,9 @@ static inline int util_fits_cpu(unsigned * * For uclamp_max, we can tolerate a drop in performance level as the * goal is to cap the task. So it's okay if it's getting less. - * - * In case of capacity inversion we should honour the inverted capacity - * for both uclamp_min and uclamp_max all the time. */ - capacity_orig = cpu_in_capacity_inversion(cpu); - if (capacity_orig) { - capacity_orig_thermal = capacity_orig; - } else { - capacity_orig = capacity_orig_of(cpu); - capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu); - } + capacity_orig = capacity_orig_of(cpu); + capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu); /* * We want to force a task to fit a cpu as implied by uclamp_max. @@ -8929,82 +8921,16 @@ static unsigned long scale_rt_capacity(i 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); - rq->cpu_capacity_orig = capacity_orig; + cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu); if (!capacity) capacity = 1; - rq->cpu_capacity = capacity; - - /* - * Detect if the performance domain is in capacity inversion state. - * - * Capacity inversion happens when another perf domain with equal or - * lower capacity_orig_of() ends up having higher capacity than this - * domain after subtracting thermal pressure. - * - * We only take into account thermal pressure in this detection as it's - * the only metric that actually results in *real* reduction of - * capacity due to performance points (OPPs) being dropped/become - * unreachable due to thermal throttling. - * - * We assume: - * * That all cpus in a perf domain have the same capacity_orig - * (same uArch). - * * Thermal pressure will impact all cpus in this perf domain - * equally. - */ - if (sched_energy_enabled()) { - unsigned long inv_cap = capacity_orig - thermal_load_avg(rq); - struct perf_domain *pd; - - rcu_read_lock(); - - pd = rcu_dereference(rq->rd->pd); - rq->cpu_capacity_inverted = 0; - - for (; pd; pd = pd->next) { - struct cpumask *pd_span = perf_domain_span(pd); - unsigned long pd_cap_orig, pd_cap; - - /* We can't be inverted against our own pd */ - if (cpumask_test_cpu(cpu_of(rq), pd_span)) - continue; - - cpu = cpumask_any(pd_span); - pd_cap_orig = arch_scale_cpu_capacity(cpu); - - if (capacity_orig < pd_cap_orig) - continue; - - /* - * handle the case of multiple perf domains have the - * same capacity_orig but one of them is under higher - * thermal pressure. We record it as capacity - * inversion. - */ - if (capacity_orig == pd_cap_orig) { - pd_cap = pd_cap_orig - thermal_load_avg(cpu_rq(cpu)); - - if (pd_cap > inv_cap) { - rq->cpu_capacity_inverted = inv_cap; - break; - } - } else if (pd_cap_orig > inv_cap) { - rq->cpu_capacity_inverted = inv_cap; - break; - } - } - - rcu_read_unlock(); - } - - trace_sched_cpu_capacity_tp(rq); + cpu_rq(cpu)->cpu_capacity = capacity; + trace_sched_cpu_capacity_tp(cpu_rq(cpu)); sdg->sgc->capacity = capacity; sdg->sgc->min_capacity = capacity; --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1041,7 +1041,6 @@ struct rq { unsigned long cpu_capacity; unsigned long cpu_capacity_orig; - unsigned long cpu_capacity_inverted; struct balance_callback *balance_callback; @@ -2879,24 +2878,6 @@ static inline unsigned long capacity_ori return cpu_rq(cpu)->cpu_capacity_orig; } -/* - * Returns inverted capacity if the CPU is in capacity inversion state. - * 0 otherwise. - * - * Capacity inversion detection only considers thermal impact where actual - * performance points (OPPs) gets dropped. - * - * Capacity inversion state happens when another performance domain that has - * equal or lower capacity_orig_of() becomes effectively larger than the perf - * domain this CPU belongs to due to thermal pressure throttling it hard. - * - * See comment in update_cpu_capacity(). - */ -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