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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED, USER_AGENT_GIT 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 C2DE4C28CC0 for ; Wed, 29 May 2019 20:37:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91F0524190 for ; Wed, 29 May 2019 20:37:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="VQwl52pf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726944AbfE2Uhu (ORCPT ); Wed, 29 May 2019 16:37:50 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:40338 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726304AbfE2UhF (ORCPT ); Wed, 29 May 2019 16:37:05 -0400 Received: by mail-io1-f68.google.com with SMTP id n5so3063416ioc.7 for ; Wed, 29 May 2019 13:37:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digitalocean.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :in-reply-to:references; bh=mxMDXOH11CG9HkxEHER6u//QzdgDeYc242m4FO3zHhs=; b=VQwl52pfbj2HNX+AUbmZeECsVhh7wZ0t9zb0xkLDHiQAGt2iBVcQ/ejQ6xRJA8Fp15 HASY5F1j0/yj7iSpimUspru643Fz0OgdcWmPNiqneBaDtDWz2wNSR2+zVhQY/jOdTlFS kyzFIfsEB9Vw3KLLmspAZdSPpDkVvL8LKaiJM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=mxMDXOH11CG9HkxEHER6u//QzdgDeYc242m4FO3zHhs=; b=BVOjA04GBGdh3bii7t0YzBLxYt9ostKW35zkQPuYw3limyKWbCXkKvDe5NrhX7q2V+ feL5BheCQPSN9lehQYL7JDBq9paDj1MoO4V3LyezzfP3+ZttO2qc9Io6sy4f0UeZBoC/ r0R2z5Ezs8fydfgxwEteuVHTMdOQ8Hy9BR1YnKK3hEpKvs/Dxaa6YtxKats3bT0YXzEI EvLY62WrlYKXgcpsiyyiMGkPDeAI4k4onXLm4SssiJzdZPn7cLKAktV7kL5wMIQeoq/7 DJgrPcL+ZI52e+uC466MKU/5hA5f6BhN5NCgjDzTcLsu4dGob0V4naQPDl+vZNf5ZL9/ SKlg== X-Gm-Message-State: APjAAAXFhNv/DNJA/uK/BWhciAOK1/IYHWpWrbVdU/lXWANEguFccuFQ 5MV/GIV3zv1Efm0BiYc/1RyCsQ== X-Google-Smtp-Source: APXvYqxkW13RPtDLKh9rmPsHJcTDyDIlmW7QV9Z+9HD171M5MCD5mb9zf5cCoFq+ssLihO4xUvNvvw== X-Received: by 2002:a5e:8704:: with SMTP id y4mr7244581ioj.135.1559162224143; Wed, 29 May 2019 13:37:04 -0700 (PDT) Received: from swap-tester ([178.128.225.14]) by smtp.gmail.com with ESMTPSA id c18sm156012iob.80.2019.05.29.13.37.03 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 13:37:03 -0700 (PDT) From: Vineeth Remanan Pillai To: Nishanth Aravamudan , Julien Desfossez , Peter Zijlstra , Tim Chen , mingo@kernel.org, tglx@linutronix.de, pjt@google.com, torvalds@linux-foundation.org Cc: linux-kernel@vger.kernel.org, subhra.mazumdar@oracle.com, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Aaron Lu , Aubrey Li , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini Subject: [RFC PATCH v3 07/16] sched: Allow put_prev_task() to drop rq->lock Date: Wed, 29 May 2019 20:36:43 +0000 Message-Id: X-Mailer: git-send-email 2.17.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra Currently the pick_next_task() loop is convoluted and ugly because of how it can drop the rq->lock and needs to restart the picking. For the RT/Deadline classes, it is put_prev_task() where we do balancing, and we could do this before the picking loop. Make this possible. Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/core.c | 2 +- kernel/sched/deadline.c | 14 +++++++++++++- kernel/sched/fair.c | 2 +- kernel/sched/idle.c | 2 +- kernel/sched/rt.c | 14 +++++++++++++- kernel/sched/sched.h | 4 ++-- kernel/sched/stop_task.c | 2 +- 7 files changed, 32 insertions(+), 8 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 32ea79fb8d29..9dfa0c53deb3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5595,7 +5595,7 @@ static void calc_load_migrate(struct rq *rq) atomic_long_add(delta, &calc_load_tasks); } -static void put_prev_task_fake(struct rq *rq, struct task_struct *prev) +static void put_prev_task_fake(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { } diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index c02b3229e2c3..45425f971eec 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1772,13 +1772,25 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) return p; } -static void put_prev_task_dl(struct rq *rq, struct task_struct *p) +static void put_prev_task_dl(struct rq *rq, struct task_struct *p, struct rq_flags *rf) { update_curr_dl(rq); update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 1); if (on_dl_rq(&p->dl) && p->nr_cpus_allowed > 1) enqueue_pushable_dl_task(rq, p); + + if (rf && !on_dl_rq(&p->dl) && need_pull_dl_task(rq, p)) { + /* + * This is OK, because current is on_cpu, which avoids it being + * picked for load-balance and preemption/IRQs are still + * disabled avoiding further scheduler activity on it and we've + * not yet started the picking loop. + */ + rq_unpin_lock(rq, rf); + pull_dl_task(rq); + rq_repin_lock(rq, rf); + } } /* diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 49707b4797de..8e3eb243fd9f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7110,7 +7110,7 @@ done: __maybe_unused; /* * Account for a descheduled task: */ -static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) +static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { struct sched_entity *se = &prev->se; struct cfs_rq *cfs_rq; diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index dd64be34881d..1b65a4c3683e 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -373,7 +373,7 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl resched_curr(rq); } -static void put_prev_task_idle(struct rq *rq, struct task_struct *prev) +static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { } diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index adec98a94f2b..51ee87c5a28a 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1593,7 +1593,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) return p; } -static void put_prev_task_rt(struct rq *rq, struct task_struct *p) +static void put_prev_task_rt(struct rq *rq, struct task_struct *p, struct rq_flags *rf) { update_curr_rt(rq); @@ -1605,6 +1605,18 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p) */ if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1) enqueue_pushable_task(rq, p); + + if (rf && !on_rt_rq(&p->rt) && need_pull_rt_task(rq, p)) { + /* + * This is OK, because current is on_cpu, which avoids it being + * picked for load-balance and preemption/IRQs are still + * disabled avoiding further scheduler activity on it and we've + * not yet started the picking loop. + */ + rq_unpin_lock(rq, rf); + pull_rt_task(rq); + rq_repin_lock(rq, rf); + } } #ifdef CONFIG_SMP diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index bfcbcbb25646..4cbe2bef92e4 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1675,7 +1675,7 @@ struct sched_class { struct task_struct * (*pick_next_task)(struct rq *rq, struct task_struct *prev, struct rq_flags *rf); - void (*put_prev_task)(struct rq *rq, struct task_struct *p); + void (*put_prev_task)(struct rq *rq, struct task_struct *p, struct rq_flags *rf); void (*set_next_task)(struct rq *rq, struct task_struct *p); #ifdef CONFIG_SMP @@ -1721,7 +1721,7 @@ struct sched_class { static inline void put_prev_task(struct rq *rq, struct task_struct *prev) { WARN_ON_ONCE(rq->curr != prev); - prev->sched_class->put_prev_task(rq, prev); + prev->sched_class->put_prev_task(rq, prev, NULL); } static inline void set_next_task(struct rq *rq, struct task_struct *next) diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 47a3d2a18a9a..8f414018d5e0 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -59,7 +59,7 @@ static void yield_task_stop(struct rq *rq) BUG(); /* the stop task should never yield, its pointless. */ } -static void put_prev_task_stop(struct rq *rq, struct task_struct *prev) +static void put_prev_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { struct task_struct *curr = rq->curr; u64 delta_exec; -- 2.17.1