From nobody Tue Oct 7 19:56:08 2025 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E77F71E8322 for ; Mon, 7 Jul 2025 20:44:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751921059; cv=none; b=YlGzfuNs1gfa6OsbfneXsYeTxk/bS1dwhnBJxRDfB+100y2CVVp7X63KE1kjl7/1Auw1EIn7UF886ZSWw/TJ54vyM5Dtf3K4+y4UIwPFLj5bIst3AjU8DevvjjA6pNYvlXtzMDQGAuznmnq/Xf+fkPkDuCACzCrQc/FvBzy4EH8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751921059; c=relaxed/simple; bh=vtzyhv9a/esCi91sq/GucpYona1JPGP894PNVA+Aruw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Kbfi7iyf7S5Uq/X6kvpE+Daux/uzJs+BLUQDAdidZzRbBdUng7PaPIyTnq7XqNQ0Xb365My/dYqvMTNSPdWKx8l3esp5mMVoLX2fvVfjdu5+W7//UbN5hcH3VFQ7C/NuugpINj14kOmgG8NDiot7hMwXvQUS/77MPu+ECtvw6vE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jstultz.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=tdlMng6J; arc=none smtp.client-ip=209.85.215.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jstultz.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tdlMng6J" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-b2fb347b3e6so4348319a12.1 for ; Mon, 07 Jul 2025 13:44:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1751921057; x=1752525857; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=GtamtensSo2O4q2/DkAjxE9NIlfjTtUqP5/1W59cAKQ=; b=tdlMng6JPjQMn2friiwjg01ItE+73Gdjdjw8E6TezqrTvxdtZRDUJjEZTuM16dRlVl fkhXrxkrUDKmMYlxZ34VLqVleeQRrwHleytTTpRIfiel5yjE7ect50O3xrNu2GqqzQ5M ztrFnAuUB4/V5CGMI0IsQbEVZvnAxYfaKGF6OWvEP0UpZXWKWhks8TexkmR+hEGEqAlg MwvwLE76AfqvrNTKMtan33DHjnHt5rgA/0JSuLaeMJT3uFFh/ZLabTz+Jui/DL683ayK V7VlKabpqLSY74FukhRBJSbUHfU1rEtO5SZaLM7tglHuFGbjnyNxIGdIkY3SsIlt4cxC Jd2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751921057; x=1752525857; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=GtamtensSo2O4q2/DkAjxE9NIlfjTtUqP5/1W59cAKQ=; b=ALmr7gfsdbw4dnpTb2tPoN4zuz4/jRiSGg+vRg3lotjEg2Uu3/LraEakpByai4Y04g qPRpXztx3OpD1M4bT3kLhFg7DGuc81JdtZjbfK7Ge3ZCyi7l6wtQO2MQZGNSOUmgBliO cXy8n+QHpsj25xcAtk25MMHz2JpypUq9qYharwW3OOa2cn0jsQRYWVPCsVY8/NwVh4iz 5oxPwglAXAbwcNKIVA+rI34DO3WV7+5dZCPcOgh+QKcKdGb/mEIDG04bQTD5mq8sS4p8 qzsoarPfHd/CD3ALsARKt6JAuQy5TWtebiCM82DnnXEN1x1fOmPp+VYbObFlpzDSFScp EIfw== X-Gm-Message-State: AOJu0YzTBbuZGuHkU8ayKRQ1aAjTlEJdX3LKzyEvbPbfmw2qguiPB/HL 1dHGqmyAF9h/KJlg3DNwZOkObKFiwB7n2tgdoHl6f0osd/3yu5j7Shjks4eIpIjoa4J8JhDcpWp nygliLbgDstd5uiUYD82v0J1s9B7bEzoz8VWl5mzKjlua/fbd78dZFfvKftq/AwFAscaNL5Fq8C gOME3h6jX4/un85cTW9CNbbGoalEW3t+jCwOhT19LWjpdYyfSb X-Google-Smtp-Source: AGHT+IG4FN6+gTahsP4YSBFaxpNQCv9V8b+i4y0+uAiReg1PMGVLD93sWSc6lTngqfi/r0t5ViTPJL40vo9c X-Received: from pgbda5.prod.google.com ([2002:a05:6a02:2385:b0:b2e:beba:356]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:b98:b0:215:fb74:2dc2 with SMTP id adf61e73a8af0-22b4214ddabmr855529637.11.1751921057122; Mon, 07 Jul 2025 13:44:17 -0700 (PDT) Date: Mon, 7 Jul 2025 20:43:48 +0000 In-Reply-To: <20250707204409.1028494-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250707204409.1028494-1-jstultz@google.com> X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250707204409.1028494-2-jstultz@google.com> Subject: [RESEND][PATCH v18 1/8] sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable From: John Stultz To: LKML Cc: John Stultz , K Prateek Nayak , Joel Fernandes , Qais Yousef , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Mel Gorman , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , Daniel Lezcano , Suleiman Souhlal , kuyo chang , hupu , kernel-team@android.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a CONFIG_SCHED_PROXY_EXEC option, along with a boot argument sched_proxy_exec=3D that can be used to disable the feature at boot time if CONFIG_SCHED_PROXY_EXEC was enabled. Also uses this option to allow the rq->donor to be different from rq->curr. Tested-by: K Prateek Nayak Signed-off-by: John Stultz --- v7: * Switch to CONFIG_SCHED_PROXY_EXEC/sched_proxy_exec=3D as suggested by Metin Kaya. * Switch boot arg from =3Ddisable/enable to use kstrtobool(), which supports =3Dyes|no|1|0|true|false|on|off, as also suggested by Metin Kaya, and print a message when a boot argument is used. v8: * Move CONFIG_SCHED_PROXY_EXEC under Scheduler Features as Suggested by Metin * Minor rework reordering with split sched contexts patch v12: * Rework for selected -> donor renaming v14: * Depend on !PREEMPT_RT to avoid build issues for now v15: * Depend on EXPERT while patch series upstreaming is in progress. v16: * Allow "sched_proxy_exec" without "=3Dtrue" to enable proxy-execution at boot time, in addition to the "sched_proxy_exec=3Dtrue" or "sched_proxy_exec=3Dfalse" options as suggested by Steven * Drop the "default n" in Kconfig as suggested by Steven * Add !SCHED_CLASS_EXT dependency until I can investigate if sched_ext can understand split contexts, as suggested by Peter v17: * Expanded the commit message a bit to clarify that the option allows the split contexts (rq->donor and rq->curr) to be different tasks, from feedback from Juri Lelli Cc: Joel Fernandes Cc: Qais Yousef Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Valentin Schneider Cc: Steven Rostedt Cc: Ben Segall Cc: Zimuzo Ezeozue Cc: Mel Gorman Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: "Paul E. McKenney" Cc: Metin Kaya Cc: Xuewen Yan Cc: K Prateek Nayak Cc: Thomas Gleixner Cc: Daniel Lezcano Cc: Suleiman Souhlal Cc: kuyo chang Cc: hupu Cc: kernel-team@android.com --- .../admin-guide/kernel-parameters.txt | 5 ++++ include/linux/sched.h | 13 +++++++++ init/Kconfig | 12 ++++++++ kernel/sched/core.c | 29 +++++++++++++++++++ kernel/sched/sched.h | 12 ++++++++ 5 files changed, 71 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index f1f2c0874da9d..5b89464ca570a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6387,6 +6387,11 @@ sa1100ir [NET] See drivers/net/irda/sa1100_ir.c. =20 + sched_proxy_exec=3D [KNL] + Enables or disables "proxy execution" style + solution to mutex-based priority inversion. + Format: + sched_verbose [KNL,EARLY] Enables verbose scheduler debug messages. =20 schedstats=3D [KNL,X86] Enable or disable scheduled statistics. diff --git a/include/linux/sched.h b/include/linux/sched.h index 4f78a64beb52c..ba2a02ead8c7e 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1664,6 +1664,19 @@ struct task_struct { randomized_struct_fields_end } __attribute__ ((aligned (64))); =20 +#ifdef CONFIG_SCHED_PROXY_EXEC +DECLARE_STATIC_KEY_TRUE(__sched_proxy_exec); +static inline bool sched_proxy_exec(void) +{ + return static_branch_likely(&__sched_proxy_exec); +} +#else +static inline bool sched_proxy_exec(void) +{ + return false; +} +#endif + #define TASK_REPORT_IDLE (TASK_REPORT + 1) #define TASK_REPORT_MAX (TASK_REPORT_IDLE << 1) =20 diff --git a/init/Kconfig b/init/Kconfig index af4c2f0854554..6844b25303913 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -875,6 +875,18 @@ config UCLAMP_BUCKETS_COUNT =20 If in doubt, use the default value. =20 +config SCHED_PROXY_EXEC + bool "Proxy Execution" + # Avoid some build failures w/ PREEMPT_RT until it can be fixed + depends on !PREEMPT_RT + # Need to investigate how to inform sched_ext of split contexts + depends on !SCHED_CLASS_EXT + # Not particularly useful until we get to multi-rq proxying + depends on EXPERT + help + This option enables proxy execution, a mechanism for mutex-owning + tasks to inherit the scheduling context of higher priority waiters. + endmenu =20 # diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8988d38d46a38..853157b27f384 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -119,6 +119,35 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_compute_energy_tp); =20 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); =20 +#ifdef CONFIG_SCHED_PROXY_EXEC +DEFINE_STATIC_KEY_TRUE(__sched_proxy_exec); +static int __init setup_proxy_exec(char *str) +{ + bool proxy_enable =3D true; + + if (*str && kstrtobool(str + 1, &proxy_enable)) { + pr_warn("Unable to parse sched_proxy_exec=3D\n"); + return 0; + } + + if (proxy_enable) { + pr_info("sched_proxy_exec enabled via boot arg\n"); + static_branch_enable(&__sched_proxy_exec); + } else { + pr_info("sched_proxy_exec disabled via boot arg\n"); + static_branch_disable(&__sched_proxy_exec); + } + return 1; +} +#else +static int __init setup_proxy_exec(char *str) +{ + pr_warn("CONFIG_SCHED_PROXY_EXEC=3Dn, so it cannot be enabled or disabled= at boot time\n"); + return 0; +} +#endif +__setup("sched_proxy_exec", setup_proxy_exec); + /* * Debugging: various feature bits * diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 475bb5998295e..6b61e0c7f6e78 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1151,10 +1151,15 @@ struct rq { */ unsigned int nr_uninterruptible; =20 +#ifdef CONFIG_SCHED_PROXY_EXEC + struct task_struct __rcu *donor; /* Scheduling context */ + struct task_struct __rcu *curr; /* Execution context */ +#else union { struct task_struct __rcu *donor; /* Scheduler context */ struct task_struct __rcu *curr; /* Execution context */ }; +#endif struct sched_dl_entity *dl_server; struct task_struct *idle; struct task_struct *stop; @@ -1349,10 +1354,17 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues= ); #define cpu_curr(cpu) (cpu_rq(cpu)->curr) #define raw_rq() raw_cpu_ptr(&runqueues) =20 +#ifdef CONFIG_SCHED_PROXY_EXEC +static inline void rq_set_donor(struct rq *rq, struct task_struct *t) +{ + rcu_assign_pointer(rq->donor, t); +} +#else static inline void rq_set_donor(struct rq *rq, struct task_struct *t) { /* Do nothing */ } +#endif =20 #ifdef CONFIG_SCHED_CORE static inline struct cpumask *sched_group_span(struct sched_group *sg); --=20 2.50.0.727.gbf7dc18ff4-goog