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 75821C28CC0 for ; Wed, 29 May 2019 20:37:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 339F024174 for ; Wed, 29 May 2019 20:37:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="HzQ+g5pE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726925AbfE2Uhq (ORCPT ); Wed, 29 May 2019 16:37:46 -0400 Received: from mail-it1-f194.google.com ([209.85.166.194]:40321 "EHLO mail-it1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726636AbfE2UhH (ORCPT ); Wed, 29 May 2019 16:37:07 -0400 Received: by mail-it1-f194.google.com with SMTP id h11so5779095itf.5 for ; Wed, 29 May 2019 13:37:06 -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=HCuNhCByhezRwLcyNJ9yd0/1pOFBH2VgXCoBl4+qgT4=; b=HzQ+g5pEJVLTPaStxTNKprUNZKRbXKi4at0o9aKsJo0aibcBaEtIy+AihtasRKlx8v 9Cz3yEWCEvHgGtMDVNdneNKL3zG/9+4W7910Td21z8Bx3pYudLSSSCcyhSvduIXdiX77 PoPiyJ3MMAL+lJRaKVA29G1TR4RYqsJQA9G6E= 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=HCuNhCByhezRwLcyNJ9yd0/1pOFBH2VgXCoBl4+qgT4=; b=hgp5bPCNrDkx4/rZDAUcwYnebEqhQo37RfXlhfF5sA05xlqVfyH0G12whBRmLMmMAQ 9r9xxtiHReRTWVxTiPHenj86YnlTAOCP29ZpQuMQoBfkaBdC8DeEuPB7dKaSA9O+pB9L ZuqH34Lx4M9zYhxyAJ7J4qHpSnLoTl0ulYQCoC5WgBmqVeeM/o5VpnGxUSMrdCNFxzKP Yg7uG50RAWJd6TAoIXyQx1y4xA1pKgBP41P3tyvK9dFfD14s7OUtLdcZZBCyjNBunPTQ QU3pTtD1w5YvIbR1VuFulHOFD0tctXtT7BufnpiR4ZwKy8tw4iqU00R5HmjkfHTxK4fu UovQ== X-Gm-Message-State: APjAAAVcmkDv1fdioPFhiDY8iZjxLZhOgCs3qLFl4AVQycroafxUBrfI zGxKfJV7NN4n/ZrmeEFQ2BED8g== X-Google-Smtp-Source: APXvYqxMASEBAnEcMFLVP85SvmjFOEwOJ18p3kSLG6ve4PMjswxVChd5sZxvRdsyLZ2TebrxPrjLbQ== X-Received: by 2002:a24:4d87:: with SMTP id l129mr165859itb.80.1559162226063; Wed, 29 May 2019 13:37:06 -0700 (PDT) Received: from swap-tester ([178.128.225.14]) by smtp.gmail.com with ESMTPSA id q16sm163009ior.75.2019.05.29.13.37.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 29 May 2019 13:37:05 -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 , Vineeth Remanan Pillai Subject: [RFC PATCH v3 09/16] sched: Introduce sched_class::pick_task() Date: Wed, 29 May 2019 20:36:45 +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 Because sched_class::pick_next_task() also implies sched_class::set_next_task() (and possibly put_prev_task() and newidle_balance) it is not state invariant. This makes it unsuitable for remote task selection. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Vineeth Remanan Pillai Signed-off-by: Julien Desfossez --- Chnages in v3 ------------- - Minor refactor to remove redundant NULL checks Changes in v2 ------------- - Fixes a NULL pointer dereference crash - Subhra Mazumdar - Tim Chen --- kernel/sched/deadline.c | 21 ++++++++++++++++----- kernel/sched/fair.c | 36 +++++++++++++++++++++++++++++++++--- kernel/sched/idle.c | 10 +++++++++- kernel/sched/rt.c | 21 ++++++++++++++++----- kernel/sched/sched.h | 2 ++ kernel/sched/stop_task.c | 21 ++++++++++++++++----- 6 files changed, 92 insertions(+), 19 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index d3904168857a..64fc444f44f9 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1722,15 +1722,12 @@ static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, return rb_entry(left, struct sched_dl_entity, rb_node); } -static struct task_struct * -pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +static struct task_struct *pick_task_dl(struct rq *rq) { struct sched_dl_entity *dl_se; struct task_struct *p; struct dl_rq *dl_rq; - WARN_ON_ONCE(prev || rf); - dl_rq = &rq->dl; if (unlikely(!dl_rq->dl_nr_running)) @@ -1741,7 +1738,19 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) p = dl_task_of(dl_se); - set_next_task_dl(rq, p); + return p; +} + +static struct task_struct * +pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_dl(rq); + if (p) + set_next_task_dl(rq, p); return p; } @@ -2388,6 +2397,8 @@ const struct sched_class dl_sched_class = { .set_next_task = set_next_task_dl, #ifdef CONFIG_SMP + .pick_task = pick_task_dl, + .select_task_rq = select_task_rq_dl, .migrate_task_rq = migrate_task_rq_dl, .set_cpus_allowed = set_cpus_allowed_dl, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e65f2dfda77a..02e5dfb85e7d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4136,7 +4136,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) * Avoid running the skip buddy, if running something else can * be done without getting too unfair. */ - if (cfs_rq->skip == se) { + if (cfs_rq->skip && cfs_rq->skip == se) { struct sched_entity *second; if (se == curr) { @@ -4154,13 +4154,13 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) /* * Prefer last buddy, try to return the CPU to a preempted task. */ - if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) + if (left && cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) se = cfs_rq->last; /* * Someone really wants this to run. If it's not unfair, run it. */ - if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) + if (left && cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) se = cfs_rq->next; clear_buddies(cfs_rq, se); @@ -6966,6 +6966,34 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ set_last_buddy(se); } +static struct task_struct * +pick_task_fair(struct rq *rq) +{ + struct cfs_rq *cfs_rq = &rq->cfs; + struct sched_entity *se; + + if (!cfs_rq->nr_running) + return NULL; + + do { + struct sched_entity *curr = cfs_rq->curr; + + se = pick_next_entity(cfs_rq, NULL); + + if (curr) { + if (se && curr->on_rq) + update_curr(cfs_rq); + + if (!se || entity_before(curr, se)) + se = curr; + } + + cfs_rq = group_cfs_rq(se); + } while (cfs_rq); + + return task_of(se); +} + static struct task_struct * pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { @@ -10677,6 +10705,8 @@ const struct sched_class fair_sched_class = { .set_next_task = set_next_task_fair, #ifdef CONFIG_SMP + .pick_task = pick_task_fair, + .select_task_rq = select_task_rq_fair, .migrate_task_rq = migrate_task_rq_fair, diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 7ece8e820b5d..e7f38da60373 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -373,6 +373,12 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl resched_curr(rq); } +static struct task_struct * +pick_task_idle(struct rq *rq) +{ + return rq->idle; +} + static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { } @@ -386,11 +392,12 @@ static void set_next_task_idle(struct rq *rq, struct task_struct *next) static struct task_struct * pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { - struct task_struct *next = rq->idle; + struct task_struct *next; if (prev) put_prev_task(rq, prev); + next = pick_task_idle(rq); set_next_task_idle(rq, next); return next; @@ -458,6 +465,7 @@ const struct sched_class idle_sched_class = { .set_next_task = set_next_task_idle, #ifdef CONFIG_SMP + .pick_task = pick_task_idle, .select_task_rq = select_task_rq_idle, .set_cpus_allowed = set_cpus_allowed_common, #endif diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 79f2e60516ef..81557224548c 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1548,20 +1548,29 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq) return rt_task_of(rt_se); } -static struct task_struct * -pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +static struct task_struct *pick_task_rt(struct rq *rq) { struct task_struct *p; struct rt_rq *rt_rq = &rq->rt; - WARN_ON_ONCE(prev || rf); - if (!rt_rq->rt_queued) return NULL; p = _pick_next_task_rt(rq); - set_next_task_rt(rq, p); + return p; +} + +static struct task_struct * +pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_rt(rq); + if (p) + set_next_task_rt(rq, p); return p; } @@ -2364,6 +2373,8 @@ const struct sched_class rt_sched_class = { .set_next_task = set_next_task_rt, #ifdef CONFIG_SMP + .pick_task = pick_task_rt, + .select_task_rq = select_task_rq_rt, .set_cpus_allowed = set_cpus_allowed_common, diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 460dd04e76af..a024dd80eeb3 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1682,6 +1682,8 @@ struct sched_class { void (*set_next_task)(struct rq *rq, struct task_struct *p); #ifdef CONFIG_SMP + struct task_struct * (*pick_task)(struct rq *rq); + int (*select_task_rq)(struct task_struct *p, int task_cpu, int sd_flag, int flags); void (*migrate_task_rq)(struct task_struct *p, int new_cpu); diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 7e1cee4e65b2..fb6c436cba6c 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -29,20 +29,30 @@ static void set_next_task_stop(struct rq *rq, struct task_struct *stop) } static struct task_struct * -pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +pick_task_stop(struct rq *rq) { struct task_struct *stop = rq->stop; - WARN_ON_ONCE(prev || rf); - if (!stop || !task_on_rq_queued(stop)) return NULL; - set_next_task_stop(rq, stop); - return stop; } +static struct task_struct * +pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_stop(rq); + if (p) + set_next_task_stop(rq, p); + + return p; +} + static void enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) { @@ -129,6 +139,7 @@ const struct sched_class stop_sched_class = { .set_next_task = set_next_task_stop, #ifdef CONFIG_SMP + .pick_task = pick_task_stop, .select_task_rq = select_task_rq_stop, .set_cpus_allowed = set_cpus_allowed_common, #endif -- 2.17.1