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 5A29FC433EF for ; Wed, 29 Jun 2022 19:48:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231386AbiF2TsJ (ORCPT ); Wed, 29 Jun 2022 15:48:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229916AbiF2TsH (ORCPT ); Wed, 29 Jun 2022 15:48:07 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DBB36218F for ; Wed, 29 Jun 2022 12:48:05 -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 E4B4A14BF; Wed, 29 Jun 2022 12:48:05 -0700 (PDT) Received: from e107158-lin.cambridge.arm.com (e107158-lin.cambridge.arm.com [10.1.197.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 54DBE3F792; Wed, 29 Jun 2022 12:48:04 -0700 (PDT) From: Qais Yousef To: Ingo Molnar , "Peter Zijlstra (Intel)" , Vincent Guittot , Dietmar Eggemann Cc: linux-kernel@vger.kernel.org, Xuewen Yan , Wei Wang , Jonathan JMChen , Hank , Qais Yousef , Yun Hsiang Subject: [PATCH 3/7] sched/uclamp: Fix fits_capacity() check in feec() Date: Wed, 29 Jun 2022 20:46:28 +0100 Message-Id: <20220629194632.1117723-4-qais.yousef@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220629194632.1117723-1-qais.yousef@arm.com> References: <20220629194632.1117723-1-qais.yousef@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As reported by Yun Hsiang [1], if a task has its uclamp_min >= 0.8 * 1024, it'll always pick the previous CPU because fits_capacity() will always return false in this case. The new util_fits_cpu() logic should handle this correctly for us beside more corner cases where similar failures could occur, like when using UCLAMP_MAX. We open code uclamp_rq_util_with() except for the clamp() part, util_fits_cpu() needs the 'raw' values to be passed to it. Also introduce uclamp_rq_{set, get}() shorthand accessors to get uclamp value for the rq. Makes the code more readable and ensures the right rules (use READ_ONCE/WRITE_ONCE) are respected transparently. [1] https://lists.linaro.org/pipermail/eas-dev/2020-July/001488.html Fixes: 1d42509e475c ("sched/fair: Make EAS wakeup placement consider uclamp restrictions") Reported-by: Yun Hsiang Signed-off-by: Qais Yousef --- kernel/sched/core.c | 10 +++++----- kernel/sched/fair.c | 26 ++++++++++++++++++++++++-- kernel/sched/sched.h | 40 ++++++++++++++++++++++++++++++++++++++-- 3 files changed, 67 insertions(+), 9 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d3e2c5a7c1b7..f5dac570d6c5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1404,7 +1404,7 @@ static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id, if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE)) return; - WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value); + uclamp_rq_set(rq, clamp_id, clamp_value); } static inline @@ -1555,8 +1555,8 @@ static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p, if (bucket->tasks == 1 || uc_se->value > bucket->value) bucket->value = uc_se->value; - if (uc_se->value > READ_ONCE(uc_rq->value)) - WRITE_ONCE(uc_rq->value, uc_se->value); + if (uc_se->value > uclamp_rq_get(rq, clamp_id)) + uclamp_rq_set(rq, clamp_id, uc_se->value); } /* @@ -1622,7 +1622,7 @@ static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, if (likely(bucket->tasks)) return; - rq_clamp = READ_ONCE(uc_rq->value); + rq_clamp = uclamp_rq_get(rq, clamp_id); /* * Defensive programming: this should never happen. If it happens, * e.g. due to future modification, warn and fixup the expected value. @@ -1630,7 +1630,7 @@ static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, SCHED_WARN_ON(bucket->value > rq_clamp); if (bucket->value >= rq_clamp) { bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value); - WRITE_ONCE(uc_rq->value, bkt_clamp); + uclamp_rq_set(rq, clamp_id, bkt_clamp); } } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 313437bea5a2..c80c676ab1bc 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6878,6 +6878,8 @@ compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd) static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) { unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX; + unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0; + unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024; struct root_domain *rd = cpu_rq(smp_processor_id())->rd; int cpu, best_energy_cpu = prev_cpu, target = -1; unsigned long cpu_cap, util, base_energy = 0; @@ -6907,6 +6909,8 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) for (; pd; pd = pd->next) { unsigned long cur_delta, spare_cap, max_spare_cap = 0; + unsigned long rq_util_min, rq_util_max; + unsigned long util_min, util_max; bool compute_prev_delta = false; unsigned long base_energy_pd; int max_spare_cap_cpu = -1; @@ -6927,8 +6931,26 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) * much capacity we can get out of the CPU; this is * aligned with sched_cpu_util(). */ - util = uclamp_rq_util_with(cpu_rq(cpu), util, p); - if (!fits_capacity(util, cpu_cap)) + if (uclamp_is_used()) { + if (uclamp_rq_is_idle(cpu_rq(cpu))) { + util_min = p_util_min; + util_max = p_util_max; + } else { + /* + * Open code uclamp_rq_util_with() except for + * the clamp() part. Ie: apply max aggregation + * only. util_fits_cpu() logic requires to + * operate on non clamped util but must use the + * max-aggregated uclamp_{min, max}. + */ + rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN); + rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX); + + util_min = max(rq_util_min, p_util_min); + util_max = max(rq_util_max, p_util_max); + } + } + if (!util_fits_cpu(util, util_min, util_max, cpu)) continue; if (cpu == prev_cpu) { diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 9599d2eea3e7..69c4d35988b9 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2907,6 +2907,23 @@ static inline unsigned long cpu_util_rt(struct rq *rq) #ifdef CONFIG_UCLAMP_TASK unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id); +static inline unsigned long uclamp_rq_get(struct rq *rq, + enum uclamp_id clamp_id) +{ + return READ_ONCE(rq->uclamp[clamp_id].value); +} + +static inline void uclamp_rq_set(struct rq *rq, enum uclamp_id clamp_id, + unsigned int value) +{ + WRITE_ONCE(rq->uclamp[clamp_id].value, value); +} + +static inline bool uclamp_rq_is_idle(struct rq *rq) +{ + return rq->uclamp_flags & UCLAMP_FLAG_IDLE; +} + /** * uclamp_rq_util_with - clamp @util with @rq and @p effective uclamp values. * @rq: The rq to clamp against. Must not be NULL. @@ -2946,8 +2963,8 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, goto out; } - min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value)); - max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value)); + min_util = max_t(unsigned long, min_util, uclamp_rq_get(rq, UCLAMP_MIN)); + max_util = max_t(unsigned long, max_util, uclamp_rq_get(rq, UCLAMP_MAX)); out: /* * Since CPU's {min,max}_util clamps are MAX aggregated considering @@ -3010,6 +3027,25 @@ static inline bool uclamp_is_used(void) { return false; } + +static inline unsigned long uclamp_rq_get(struct rq *rq, + enum uclamp_id clamp_id) +{ + if (clamp_id == UCLAMP_MIN) + return 0; + + return SCHED_CAPACITY_SCALE; +} + +static inline void uclamp_rq_set(struct rq *rq, enum uclamp_id clamp_id, + unsigned int value) +{ +} + +static inline bool uclamp_rq_is_idle(struct rq *rq) +{ + return false; +} #endif /* CONFIG_UCLAMP_TASK */ #ifdef CONFIG_HAVE_SCHED_AVG_IRQ -- 2.25.1