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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,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 B3A64C282DD for ; Tue, 23 Apr 2019 16:19:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 71198208E4 for ; Tue, 23 Apr 2019 16:19:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="U8+4clxK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728699AbfDWQSv (ORCPT ); Tue, 23 Apr 2019 12:18:51 -0400 Received: from mail-it1-f196.google.com ([209.85.166.196]:51106 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728658AbfDWQSs (ORCPT ); Tue, 23 Apr 2019 12:18:48 -0400 Received: by mail-it1-f196.google.com with SMTP id q14so1166058itk.0 for ; Tue, 23 Apr 2019 09:18:47 -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=dkhRa3ShD8vJ+VDsmWu0NfonjImY+JY8izl36A7u4Kw=; b=U8+4clxKeMOfw3mgM9jZBM9Bva9fEZov8mK2b5ZQTe2bYtTeiimJEPEYWbBiDr8IWG XXHProOTTyIliuRU8EEeaElPXxdiKfG3xdBD7IOGjk4Ln/jLmcmjPPpusIEpNeNxfBS/ 22qYFMIKrH4q5ARuhEl20PetIdcJoxJPlGecg= 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=dkhRa3ShD8vJ+VDsmWu0NfonjImY+JY8izl36A7u4Kw=; b=j5WYHamAgE/lUYUK/VNAqzFVeHr09E79Uht0B9Skqe0+Mp1J42XKCVnbFZB7YB0soI 190y1kowag+begxSyC3HIrS/04VvrjM8P63IVn+R1m6D0Oo4k22UsE4sHpbt7CgKuCtI d3Xxu9OrgRTJXISE4o4SxEb5KgzW2KZEOAvcpk9JRwwYL9D6tdhX1g8YxZLTa5RPJZrA brdGAPxhbL5xnw6vofZfQOuTtfcHhiGiwHdgkEo4RA9jNRsszhtqvXroB6xCOh2DukRJ i2luEvKda5VQCGdGCTHwvK36C7+rjnsAl9qlxdLaIJ2M7yJ+jjPEuA0jukuCU565W8S+ nDgg== X-Gm-Message-State: APjAAAXX2bqTs+y3U3NsJmwlKbzfeReaBgKNFw2BdQ0yuzyneJqS579T KeGuVyVs+sUORBTpf3n7AaWR0A== X-Google-Smtp-Source: APXvYqx5KjvsZlTilHkebjMr/Skg3XD9QoZH85PmZCOZch1geK4HuCprnfSaYRPTEqYJOzMatkJTzA== X-Received: by 2002:a05:660c:d4:: with SMTP id q20mr2630406itk.102.1556036326675; Tue, 23 Apr 2019 09:18:46 -0700 (PDT) Received: from swap-tester ([178.128.225.14]) by smtp.gmail.com with ESMTPSA id s7sm1450985ioo.17.2019.04.23.09.18.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 23 Apr 2019 09:18:46 -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 v2 07/17] sched: Allow put_prev_task() to drop rq->lock Date: Tue, 23 Apr 2019 16:18:12 +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 (Intel) 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 fadfbfe7d573..56791c0318a2 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1773,13 +1773,25 @@ 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 f7e631e692a3..41ec5e68e1c5 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7081,7 +7081,7 @@ 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