From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 599E213D2EC for ; Wed, 28 Feb 2024 23:34:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709163282; cv=none; b=Thxr8IB6LcBlXiSugGHeV8m10lJLibAPnEcl2bFVuLs4Ia+1QbbFgDDIGPkGIcVvZ2Sh846yrj/9DfqvpbY6SsYiSPOY7aD+HZ94S+Ci+e0qmDuRX+nG3fG2z9SFm0WrhgYZXsL/n3HNBQH3Wmqo5QAKWJ1VgMFWw8Y9AMrbu4s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709163282; c=relaxed/simple; bh=+MsY1IJSTlCHzh7O9mUgcv30fwS5Nx5yrNhbZQvAZyA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ayE0Co5FrMZE7UYW/jOeO8YjxI4wISNd6BDkdsQCdy54sSxM0zQl2cvHOfouekMd1kEUR0vlQ0DCzXsQfEoy3KoXEmztC7BTwlq5twesgZ7n8vKx+/p9zzlxJEOC/32eWHoZsKv3Koh5ADa+T4MnuH2uccMQusNeK3zROyKQwJ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 199A31FB; Wed, 28 Feb 2024 15:35:17 -0800 (PST) Received: from [192.168.2.96] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 617E33F73F; Wed, 28 Feb 2024 15:34:34 -0800 (PST) Message-ID: <1146ab2f-56c7-43f3-b26b-d91d2bd08556@arm.com> Date: Thu, 29 Feb 2024 00:34:28 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] sched/fair: Add EAS checks before updating overutilized Content-Language: en-US To: Shrikanth Hegde , Pierre Gondois Cc: yu.c.chen@intel.com, linux-kernel@vger.kernel.org, nysal@linux.ibm.com, aboorvad@linux.ibm.com, srikar@linux.vnet.ibm.com, vschneid@redhat.com, morten.rasmussen@arm.com, qyousef@layalina.io, mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org References: <20240228071621.602596-1-sshegde@linux.ibm.com> <20240228071621.602596-2-sshegde@linux.ibm.com> <86f000a3-3068-4c57-858d-c00e3eb6e974@arm.com> <72c2d279-90ae-4612-9b96-e579333b8088@linux.ibm.com> From: Dietmar Eggemann In-Reply-To: <72c2d279-90ae-4612-9b96-e579333b8088@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 28/02/2024 18:24, Shrikanth Hegde wrote: > > > On 2/28/24 9:28 PM, Pierre Gondois wrote: [...] > But we will do some extra computation currently and then not use it if it > Non-EAS case in update_sg_lb_stats > > Would something like this makes sense? > @@ -9925,7 +9925,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, > if (nr_running > 1) > *sg_status |= SG_OVERLOAD; > > - if (cpu_overutilized(i)) > + if (sched_energy_enabled() && cpu_overutilized(i)) > *sg_status |= SG_OVERUTILIZED; Yes, we could also disable the setting of OU in load_balance in the none !EAS case. [...] >> NIT: >> When called from check_update_overutilized_status(), >> sched_energy_enabled() will be checked twice. > Yes. > But, I think that's okay since it is a static branch check at best. > This way it keeps the code simpler. You could keep the ched_energy_enabled() outside of the new set_overutilized_status() to avoid this: -->8-- --- kernel/sched/fair.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 32bc98d9123d..c82164bf45f3 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6676,12 +6676,19 @@ static inline bool cpu_overutilized(int cpu) return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu); } +static inline void set_overutilized_status(struct rq *rq, unsigned int val) +{ + WRITE_ONCE(rq->rd->overutilized, val); + trace_sched_overutilized_tp(rq->rd, val); +} + static inline void update_overutilized_status(struct rq *rq) { - if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) { - WRITE_ONCE(rq->rd->overutilized, SG_OVERUTILIZED); - trace_sched_overutilized_tp(rq->rd, SG_OVERUTILIZED); - } + if (!sched_energy_enabled()) + return; + + if (!READ_ONCE(rq->rd->overutilized) && cpu_overutilized(rq->cpu)) + set_overutilized_status(rq, SG_OVERUTILIZED); } #else static inline void update_overutilized_status(struct rq *rq) { } @@ -10755,19 +10762,16 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd env->fbq_type = fbq_classify_group(&sds->busiest_stat); if (!env->sd->parent) { - struct root_domain *rd = env->dst_rq->rd; - /* update overload indicator if we are at root domain */ - WRITE_ONCE(rd->overload, sg_status & SG_OVERLOAD); + WRITE_ONCE(env->dst_rq->rd->overload, sg_status & SG_OVERLOAD); /* Update over-utilization (tipping point, U >= 0) indicator */ - WRITE_ONCE(rd->overutilized, sg_status & SG_OVERUTILIZED); - trace_sched_overutilized_tp(rd, sg_status & SG_OVERUTILIZED); - } else if (sg_status & SG_OVERUTILIZED) { - struct root_domain *rd = env->dst_rq->rd; - - WRITE_ONCE(rd->overutilized, SG_OVERUTILIZED); - trace_sched_overutilized_tp(rd, SG_OVERUTILIZED); + if (sched_energy_enabled()) { + set_overutilized_status(env->dst_rq, + sg_status & SG_OVERUTILIZED); + } + } else if (sched_energy_enabled() && sg_status & SG_OVERUTILIZED) { + set_overutilized_status(env->dst_rq, SG_OVERUTILIZED); } update_idle_cpu_scan(env, sum_util); -- 2.25.1