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=-9.8 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 7C582C3F2CE for ; Wed, 4 Mar 2020 17:00:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 487A52465D for ; Wed, 4 Mar 2020 17:00:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="AuEPgc4X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388478AbgCDRAs (ORCPT ); Wed, 4 Mar 2020 12:00:48 -0500 Received: from mail-qt1-f196.google.com ([209.85.160.196]:35389 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388333AbgCDRAL (ORCPT ); Wed, 4 Mar 2020 12:00:11 -0500 Received: by mail-qt1-f196.google.com with SMTP id v15so1901766qto.2 for ; Wed, 04 Mar 2020 09:00:10 -0800 (PST) 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=dF5F37k3eAJY4EzLRT+ogSrkSEWzuWuSPFPIFXk7yLU=; b=AuEPgc4XB8gCdH4OSrC3SLQX+9igmmal9g5h3oo40xgv8x9kYo9lVO/I6qpQWqfoU6 hnvu5eQ/uHmy+EVUZCGHofI8OugijE/3esn8WRzF5w67QD+fTKbHgMmQwmzMvDZx5WbD CFNlSMaBSVZ0LXU/DUuPL8xqrbnTNYH2hUUOc= 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=dF5F37k3eAJY4EzLRT+ogSrkSEWzuWuSPFPIFXk7yLU=; b=j63j6RDD8d8VEWsphmDC0pdycVR6PknlRlYlGnJOkAoRKOWQlDpt4050YwNf9eQRLp gXRLK6pNMlXzxQxG79m5Au2sDzR8XBaXhxoixBgTshNBIn/ZsxDRLkT4C2/8Au4+uXvT 67pMSNgi1v/i0/YcdTrgInaXOuSyxduMTPlPLn6apSPj3dRNKjFxGNdIeSUN3+8kB49z IbLDOXjVLv9WkyVk24n92cUjz3nI0Zf1tKqVayuHNsN99JnkOuYVg7geEKI6eqk81iOQ cvaT/vjD2BkpG6bit81m9Hw8FU3ZdFIqTwKcDt6QvSLcLgrlZLXoPhKwI71R4wN++UlZ EJ6g== X-Gm-Message-State: ANhLgQ3dcLnzqDXa/3Cysb8ye4ZbIhrXUp4TpFCtM9u8Eh76BQFOFVOx TnezvNuBBjZodgR/JZz9u7CmKQ== X-Google-Smtp-Source: ADFU+vtEWF216MFJ5iO3xgxjJCoTg+kxl+NwWiWzOSBXrJgIiNXvSKPsu3v/vFzfCs3ge7IXtuc+Nw== X-Received: by 2002:ac8:2f8b:: with SMTP id l11mr3300875qta.65.1583341209097; Wed, 04 Mar 2020 09:00:09 -0800 (PST) Received: from s2r5node9 ([162.243.188.99]) by smtp.gmail.com with ESMTPSA id i64sm12345139qke.56.2020.03.04.09.00.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Mar 2020 09:00:08 -0800 (PST) From: vpillai 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, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Aaron Lu , Aubrey Li , aubrey.li@linux.intel.com, Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , Joel Fernandes , joel@joelfernandes.org, Vineeth Remanan Pillai Subject: [RFC PATCH 02/13] sched: Introduce sched_class::pick_task() Date: Wed, 4 Mar 2020 16:59:52 +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 --- kernel/sched/deadline.c | 16 ++++++++++++++-- kernel/sched/fair.c | 34 +++++++++++++++++++++++++++++++--- kernel/sched/idle.c | 6 ++++++ kernel/sched/rt.c | 14 ++++++++++++-- kernel/sched/sched.h | 3 +++ kernel/sched/stop_task.c | 13 +++++++++++-- 6 files changed, 77 insertions(+), 9 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index ded147f84382..ee7fd8611ee4 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1773,7 +1773,7 @@ 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) +static struct task_struct *pick_task_dl(struct rq *rq) { struct sched_dl_entity *dl_se; struct dl_rq *dl_rq = &rq->dl; @@ -1785,7 +1785,18 @@ static struct task_struct *pick_next_task_dl(struct rq *rq) dl_se = pick_next_dl_entity(rq, dl_rq); BUG_ON(!dl_se); p = dl_task_of(dl_se); - set_next_task_dl(rq, p, true); + + return p; +} + +static struct task_struct *pick_next_task_dl(struct rq *rq) +{ + struct task_struct *p; + + p = pick_task_dl(rq); + if (p) + set_next_task_dl(rq, p, true); + return p; } @@ -2442,6 +2453,7 @@ const struct sched_class dl_sched_class = { #ifdef CONFIG_SMP .balance = balance_dl, + .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 3b218753bf7a..5eaaf0c4d9ad 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4228,7 +4228,7 @@ 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) { @@ -4246,13 +4246,13 @@ 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); @@ -6642,6 +6642,33 @@ 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); +} + struct task_struct * pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { @@ -10771,6 +10798,7 @@ const struct sched_class fair_sched_class = { #ifdef CONFIG_SMP .balance = balance_fair, + .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 f8653290de95..46c18e3dab13 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -397,6 +397,11 @@ static void set_next_task_idle(struct rq *rq, struct task_struct *next, bool fir schedstat_inc(rq->sched_goidle); } +static struct task_struct *pick_task_idle(struct rq *rq) +{ + return rq->idle; +} + struct task_struct *pick_next_task_idle(struct rq *rq) { struct task_struct *next = rq->idle; @@ -469,6 +474,7 @@ const struct sched_class idle_sched_class = { #ifdef CONFIG_SMP .balance = balance_idle, + .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 fc7d6706b209..d044baedc617 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1567,7 +1567,7 @@ 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) +static struct task_struct *pick_task_rt(struct rq *rq) { struct task_struct *p; @@ -1575,7 +1575,16 @@ static struct task_struct *pick_next_task_rt(struct rq *rq) return NULL; p = _pick_next_task_rt(rq); - set_next_task_rt(rq, p, true); + + return p; +} + +static struct task_struct *pick_next_task_rt(struct rq *rq) +{ + struct task_struct *p = pick_task_rt(rq); + if (p) + set_next_task_rt(rq, p, true); + return p; } @@ -2368,6 +2377,7 @@ const struct sched_class rt_sched_class = { #ifdef CONFIG_SMP .balance = balance_rt, + .pick_task = pick_task_rt, .select_task_rq = select_task_rq_rt, .set_cpus_allowed = set_cpus_allowed_common, .rq_online = rq_online_rt, diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a306008a12f7..a8335e3078ab 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1724,6 +1724,9 @@ struct sched_class { #ifdef CONFIG_SMP int (*balance)(struct rq *rq, struct task_struct *prev, struct rq_flags *rf); + + 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 4c9e9975684f..0611348edb28 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -34,15 +34,23 @@ static void set_next_task_stop(struct rq *rq, struct task_struct *stop, bool fir stop->se.exec_start = rq_clock_task(rq); } -static struct task_struct *pick_next_task_stop(struct rq *rq) +static struct task_struct *pick_task_stop(struct rq *rq) { if (!sched_stop_runnable(rq)) return NULL; - set_next_task_stop(rq, rq->stop, true); return rq->stop; } +static struct task_struct *pick_next_task_stop(struct rq *rq) +{ + struct task_struct *p = pick_task_stop(rq); + if (p) + set_next_task_stop(rq, p, true); + + return p; +} + static void enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) { @@ -130,6 +138,7 @@ const struct sched_class stop_sched_class = { #ifdef CONFIG_SMP .balance = balance_stop, + .pick_task = pick_task_stop, .select_task_rq = select_task_rq_stop, .set_cpus_allowed = set_cpus_allowed_common, #endif -- 2.17.1