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 X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B55FC433DF for ; Fri, 22 May 2020 14:59:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 498B3205CB for ; Fri, 22 May 2020 14:59:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dxY4L6Uz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731372AbgEVO7H (ORCPT ); Fri, 22 May 2020 10:59:07 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:42285 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730931AbgEVO6z (ORCPT ); Fri, 22 May 2020 10:58:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590159533; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5XaoLAqqnX0AjePEzM4E513mSIH0je3L0zFu2bL8d6Y=; b=dxY4L6UzW5VvzYOksfVonkAh0yZU0iUMcsSaY0IT+//lNgPC59n2Pjoq5YeLAzHGt6Iyvu 1BgjeI1OznHd2VrhNYsDqRhCMK6Bk7+9BfSAAZHGi/MAvOw7cHnw2HMb9BpHLXqbM5dPni RR+6GxOn1H8cZlzxwaJw9lVqmBeuJBU= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-180-sIr1V2gUNImJfayYAzweSw-1; Fri, 22 May 2020 10:58:52 -0400 X-MC-Unique: sIr1V2gUNImJfayYAzweSw-1 Received: by mail-wr1-f71.google.com with SMTP id z10so4529066wrs.2 for ; Fri, 22 May 2020 07:58:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=5XaoLAqqnX0AjePEzM4E513mSIH0je3L0zFu2bL8d6Y=; b=DL/DF0nFh2F+s/BdGGfsRdBhC53exYIrqMKHmhdgRhTy26CHL6dGRtSs6qlwzfvd0H J1S3GUIHBKnbCDW/GerWgGhGhehnm4IQbTl/oaLmtXgvg8C58tm+1ln6Dwh4sq978BIP JNTWc/N46U4Iqjln1EXy2EC2SZuTKvu58fGAjbbtI1p964b0gbuA3it5+22kSpFaL4GI 97rhzV6ki8qQV8bQVmczxs/RJ5JcGuJHAlv6E98aJeKQrFLkGEy8IX8uLQLAHJl/68MP F0wgzTYD8kvq95opsFBAFXlYcsF3P7usHAqVRoBaYa5ldolYv8/3PQs8qBKpcL6DPpit AiJw== X-Gm-Message-State: AOAM532IP5uAHjQivXEeR4VkAg8p9c+NM5UkdTHAzmVhu+MZcDYwyj8D svp5d78Xct6sQxaPK24DcrIVE57VkV7s9awSsUj8xOR9AJuD5weXn7h/X4ksHU31bjmFjtLd2uL jzrnOBmyzNf1JcJSqIHwxh3OB X-Received: by 2002:a1c:4c16:: with SMTP id z22mr1575921wmf.17.1590159529716; Fri, 22 May 2020 07:58:49 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyaNJD2NxswEbp3KjC42VAxXLa9+U2YeakcBt5MFrZihfT1BqfmtBLgzImUGUozDrmUo7mKVQ== X-Received: by 2002:a1c:4c16:: with SMTP id z22mr1575900wmf.17.1590159529395; Fri, 22 May 2020 07:58:49 -0700 (PDT) Received: from localhost.localdomain ([151.29.176.125]) by smtp.gmail.com with ESMTPSA id z7sm9728837wrl.88.2020.05.22.07.58.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 May 2020 07:58:48 -0700 (PDT) Date: Fri, 22 May 2020 16:58:46 +0200 From: Juri Lelli To: Dietmar Eggemann Cc: Ingo Molnar , Peter Zijlstra , Vincent Guittot , Steven Rostedt , Luca Abeni , Daniel Bristot de Oliveira , Wei Wang , Quentin Perret , Alessio Balsini , Pavan Kondeti , Patrick Bellasi , Morten Rasmussen , Valentin Schneider , Qais Yousef , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/5] sched/deadline: Make DL capacity-aware Message-ID: <20200522145846.GE600689@localhost.localdomain> References: <20200520134243.19352-1-dietmar.eggemann@arm.com> <20200520134243.19352-5-dietmar.eggemann@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200520134243.19352-5-dietmar.eggemann@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/05/20 15:42, Dietmar Eggemann wrote: > From: Luca Abeni > > The current SCHED_DEADLINE (DL) scheduler uses a global EDF scheduling > algorithm w/o considering CPU capacity or task utilization. > This works well on homogeneous systems where DL tasks are guaranteed > to have a bounded tardiness but presents issues on heterogeneous > systems. > > A DL task can migrate to a CPU which does not have enough CPU capacity > to correctly serve the task (e.g. a task w/ 70ms runtime and 100ms > period on a CPU w/ 512 capacity). > > Add the DL fitness function dl_task_fits_capacity() for DL admission > control on heterogeneous systems. A task fits onto a CPU if: > > CPU original capacity / 1024 >= task runtime / task deadline > > Use this function on heterogeneous systems to try to find a CPU which > meets this criterion during task wakeup, push and offline migration. > > On homogeneous systems the original behavior of the DL admission > control should be retained. > > Signed-off-by: Luca Abeni > Signed-off-by: Dietmar Eggemann > --- > kernel/sched/cpudeadline.c | 14 +++++++++++++- > kernel/sched/deadline.c | 18 ++++++++++++++---- > kernel/sched/sched.h | 15 +++++++++++++++ > 3 files changed, 42 insertions(+), 5 deletions(-) > > diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c > index 5cc4012572ec..8630f2a40a3f 100644 > --- a/kernel/sched/cpudeadline.c > +++ b/kernel/sched/cpudeadline.c > @@ -121,7 +121,19 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, > > if (later_mask && > cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) { > - return 1; > + int cpu; > + > + if (!static_branch_unlikely(&sched_asym_cpucapacity)) > + return 1; > + > + /* Ensure the capacity of the CPUs fits the task. */ > + for_each_cpu(cpu, later_mask) { > + if (!dl_task_fits_capacity(p, cpu)) > + cpumask_clear_cpu(cpu, later_mask); > + } > + > + if (!cpumask_empty(later_mask)) > + return 1; > } else { > int best_cpu = cpudl_maximum(cp); > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index fa8566517715..f2e8f5a36707 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -1643,6 +1643,7 @@ static int > select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) > { > struct task_struct *curr; > + bool select_rq; > struct rq *rq; > > if (sd_flag != SD_BALANCE_WAKE) > @@ -1662,10 +1663,19 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) > * other hand, if it has a shorter deadline, we > * try to make it stay here, it might be important. > */ > - if (unlikely(dl_task(curr)) && > - (curr->nr_cpus_allowed < 2 || > - !dl_entity_preempt(&p->dl, &curr->dl)) && > - (p->nr_cpus_allowed > 1)) { > + select_rq = unlikely(dl_task(curr)) && > + (curr->nr_cpus_allowed < 2 || > + !dl_entity_preempt(&p->dl, &curr->dl)) && > + p->nr_cpus_allowed > 1; > + > + /* > + * Take the capacity of the CPU into account to > + * ensure it fits the requirement of the task. > + */ > + if (static_branch_unlikely(&sched_asym_cpucapacity)) > + select_rq |= !dl_task_fits_capacity(p, cpu); > + > + if (select_rq) { > int target = find_later_rq(p); > > if (target != -1 && > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 14cb6a97e2d2..6ebbb1f353c4 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -317,6 +317,21 @@ static inline bool __dl_overflow(struct dl_bw *dl_b, unsigned long cap, > cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw; > } > > +/* > + * Verify the fitness of task @p to run on @cpu taking into account the > + * CPU original capacity and the runtime/deadline ratio of the task. > + * > + * The function will return true if the CPU original capacity of the > + * @cpu scaled by SCHED_CAPACITY_SCALE >= runtime/deadline ratio of the > + * task and false otherwise. > + */ > +static inline bool dl_task_fits_capacity(struct task_struct *p, int cpu) > +{ > + unsigned long cap = arch_scale_cpu_capacity(cpu); > + > + return cap_scale(p->dl.dl_deadline, cap) >= p->dl.dl_runtime; > +} > + > extern void init_dl_bw(struct dl_bw *dl_b); > extern int sched_dl_global_validate(void); > extern void sched_dl_do_global(void); > -- Acked-by: Juri Lelli