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=-9.9 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, 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 923C2CA9EC5 for ; Wed, 30 Oct 2019 18:34:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C78C208E3 for ; Wed, 30 Oct 2019 18:34:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="haj7hgDN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728052AbfJ3SeS (ORCPT ); Wed, 30 Oct 2019 14:34:18 -0400 Received: from mail-yb1-f196.google.com ([209.85.219.196]:45386 "EHLO mail-yb1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727995AbfJ3SeN (ORCPT ); Wed, 30 Oct 2019 14:34:13 -0400 Received: by mail-yb1-f196.google.com with SMTP id q143so1290396ybg.12 for ; Wed, 30 Oct 2019 11:34:13 -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=tBQRYzPOu2X0VuL5aGW3hRK0A7H69nk97Z0lgRZxnPo=; b=haj7hgDNm8/t8vU4aHKMsYkFUWKR5ustCTfRZ9xLeeAunkcHJfoDv8VZFnoMLia/go 3eQ5FOmuWv3N5MUO8CULiFz1ZMHmWTdVajbCIouKQ78iV7IyDfw+5Xo1ufWrtfa4zfIc JjVZi50gSSm5QMx6LuvPVacqcTRnZi+4dL1ig= 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=tBQRYzPOu2X0VuL5aGW3hRK0A7H69nk97Z0lgRZxnPo=; b=XwKf5DrJ3pbvMkZbWsvodP0eFLKOTlw8BqW2LrJkLR5YR5PpYr69remBP5DEY26PGw qFYnT19QsaPh7nDFRnBhJxv+OQkU7CpZm23bRwADoYXC3ydrIEg/Px5M017J5EDx0lvO jrtiKiAMuO6uWbSnZhV2/J8yzPXHyGlZHWwIC7eCCJhoxxOWnKZil+eeTo4uv8yfq3ue ZyFHRn9PYJIf96MA62WnXdd1naG6t7ouxvsAWEglgGvFaYAIuYJReEPS2siUhWcjHoXl 0JcO4yggWT1w+dJ5c6B8h8blk6enqj2Ro1a6W743fnRkXHvWtJos3Cx2fU+aPYOsMRwG ZVzA== X-Gm-Message-State: APjAAAWL382YfpHegReoaXvEhsJfT/qzX94eU3rjRH5avHQPl7wwh345 aM3GJzLct2g5UVKdQRvQIyrZBg== X-Google-Smtp-Source: APXvYqwdB85ZkJAPWVqnzQjzGKF1P96CUYkRcEIOSbO924SSbXTvJF5tIVtdmmQZXdjV5y/qjtWfWg== X-Received: by 2002:a25:fc26:: with SMTP id v38mr647354ybd.322.1572460452756; Wed, 30 Oct 2019 11:34:12 -0700 (PDT) Received: from vpillai-dev.sfo2.internal.digitalocean.com ([138.68.32.68]) by smtp.gmail.com with ESMTPSA id k62sm245693ywd.72.2019.10.30.11.34.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 30 Oct 2019 11:34:12 -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, Dario Faggioli , 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 v4 07/19] sched: Allow put_prev_task() to drop rq->lock Date: Wed, 30 Oct 2019 18:33:20 +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 95cc10ecc7c9..3fa7d37f2879 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6015,7 +6015,7 @@ 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 38b45f2f890b..416e06c97e98 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 c6b6835a5945..7ee57472d88e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6930,7 +6930,7 @@ 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 3ff4889196e1..5848ae3d5210 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -374,7 +374,7 @@ 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 a857945772d1..a7d9656f70b5 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 dc889af24efb..8b86b24a3ccd 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1718,7 +1718,7 @@ 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 @@ -1764,7 +1764,7 @@ 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