From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (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 2C21713A418 for ; Sat, 12 Apr 2025 06:03:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744437789; cv=none; b=iONkfn8S9G7K9MtMDXjl5O1GGFVt1xH4k9UnPbjLHmupZY/HGkA9Wgl4hqr+1/1MS3P4m3wjd8DhAhOojSNN1MzWT0la24ojcfjIdNWsv7/+wR//9nny9vA7+SZeDxEF8HZQJ9t/Z42ACvVznfwamEyOuF7k0uQyByiSl7agFw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744437789; c=relaxed/simple; bh=CAwtDqXGs1bHF5//VqV77rIjPIExC0e0uBtxtG4yEJY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=laU0u0IoLMfbNeVCFq358nIQON6zbZFHk8r7edtoGbbfikbp+MwEKtwu7B4VnNERV+VodDrdXUjUs4CV1sXhUsgxPt5mlkKVV96WvC3auSvGIXdnysK1er+VXI0l55SyffYggJeSbfHcSzEmcXgqGcYdOgpcHaK7PwVi4jrqAgA= 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=dZvmarxT; arc=none smtp.client-ip=209.85.216.73 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="dZvmarxT" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-2ff7aecba07so2582717a91.2 for ; Fri, 11 Apr 2025 23:03:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1744437787; x=1745042587; 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=SaH1XVz/XdC6yPqQ//7wehgj0cXdD7WNC52y2uOHy6M=; b=dZvmarxTqIFRydfhExEuOCV17stmE34EOAs2r+0F5KpRDVFYekBTJrf+fWd4IDfC9j Zy1uGWJJP4S9LMCyArOg6+npK02VmcAGgWzz5AySuBRLhUK+ZPMYqb8bA17hVmWn/66X O3jDvt7h1/MWQtNIThUzi7MfizNz6Jht/qWFXEuG5W+gH2KYgLcVhPC4+sKvYKHmFgPp HF9fhrEBfYYFkO10OPS58YuDxKA/CNNUKDLrEAQTGnWaTkxJFJVyWGTIObo9siybVNmq kDtQ/llQf9V9f/t1RKBDPusOvU2/ImvLSDRdvLz0RtWMVv42D3jcRdi7XiXlcmMy4WED GtQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744437787; x=1745042587; 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=SaH1XVz/XdC6yPqQ//7wehgj0cXdD7WNC52y2uOHy6M=; b=gWdZhhBg6OLtfrBL3QR9i9O4UzxjnzZJ30vSPIRziuOVPNnvL3DoPM0gjOP5DCHee3 NBBZ7dREeUCJL6QLUuKjff5bPTWtAroV7BnL0KnasiVo5PDslPK/BK+8p6XwZ+T5neDP wRgq1AAtnzsUSEgAylFBoPKECRBt+Cp6fZCEkXWbA2qXDy4Krk1XmiILqIAI3cIS5JzY WOvpWWh2oH7CIBDSoSDO88tWbBWMi+Jdg4GcqXtdwmY3RY2GphyFEw66stPqIzQqWR1E eer4LTmPnx+SATRlo8oVA3pvZtNNLcZ9Ey5AbVnYtpqo2WVBLoEnfFH8EM2/X/t3j66b Lsaw== X-Gm-Message-State: AOJu0Yx8grZ7li56Ybcx/xCqReR0hURJV2uyidmaHhD5a5EcJPWCU+PI kU97ykuar7HN8ie7LgazNGM5WHm00aY/taAGi+UUMOcbeKdlmgh0nJGA+32AVRnoib3LZVpeHHo OxiOEhV06KW0NmYBlN9EDprzaKy8gZAMuM7C0Kpi59LUxOtk2dx+sV8ujSlW31JUxMUtqAV00WQ 6SsZQukuf5dfE42+uqWPjACqnr3/wL1+7u8nOXoLZDrVPZ X-Google-Smtp-Source: AGHT+IFpmeOKYVxsd1mvmwrK4y8aUz+yH7zrpJiQKm+J4XYkGaJTppiJ4/IJkLg8Hoa60Qn3wwsGI4DExiP1 X-Received: from pjbkl8.prod.google.com ([2002:a17:90b:4988:b0:2ff:611c:bae8]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:c88f:b0:301:98fc:9b2f with SMTP id 98e67ed59e1d1-30823660373mr6059313a91.1.1744437787199; Fri, 11 Apr 2025 23:03:07 -0700 (PDT) Date: Fri, 11 Apr 2025 23:02:35 -0700 In-Reply-To: <20250412060258.3844594-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250412060258.3844594-1-jstultz@google.com> X-Mailer: git-send-email 2.49.0.604.gff1f9ca942-goog Message-ID: <20250412060258.3844594-2-jstultz@google.com> Subject: [PATCH v16 1/7] sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable From: John Stultz To: LKML Cc: John Stultz , 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 , K Prateek Nayak , Thomas Gleixner , Daniel Lezcano , Suleiman Souhlal , kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Add a CONFIG_SCHED_PROXY_EXEC option, along with a boot argument sched_proxy_exec= that can be used to disable the feature at boot time if CONFIG_SCHED_PROXY_EXEC was enabled. 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: kernel-team@android.com Tested-by: K Prateek Nayak Signed-off-by: John Stultz --- v7: * Switch to CONFIG_SCHED_PROXY_EXEC/sched_proxy_exec= as suggested by Metin Kaya. * Switch boot arg from =disable/enable to use kstrtobool(), which supports =yes|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 "=true" to enable proxy-execution at boot time, in addition to the "sched_proxy_exec=true" or "sched_proxy_exec=false" 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 --- .../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/Documentation/admin-guide/kernel-parameters.txt index 76e538c77e316..b21cb89a09831 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6307,6 +6307,11 @@ sa1100ir [NET] See drivers/net/irda/sa1100_ir.c. + sched_proxy_exec= [KNL] + Enables or disables "proxy execution" style + solution to mutex-based priority inversion. + Format: + sched_verbose [KNL,EARLY] Enables verbose scheduler debug messages. schedstats= [KNL,X86] Enable or disable scheduled statistics. diff --git a/include/linux/sched.h b/include/linux/sched.h index f96ac19828934..3cdd598aaa9aa 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1663,6 +1663,19 @@ struct task_struct { */ }; +#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) diff --git a/init/Kconfig b/init/Kconfig index dd2ea3b9a7992..23f6edff481b2 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -883,6 +883,18 @@ config UCLAMP_BUCKETS_COUNT If in doubt, use the default value. +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 # diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c81cf642dba05..82817650a635b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -118,6 +118,35 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_compute_energy_tp); DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); +#ifdef CONFIG_SCHED_PROXY_EXEC +DEFINE_STATIC_KEY_TRUE(__sched_proxy_exec); +static int __init setup_proxy_exec(char *str) +{ + bool proxy_enable = true; + + if (*str && kstrtobool(str + 1, &proxy_enable)) { + pr_warn("Unable to parse sched_proxy_exec=\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=n, 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 47972f34ea701..154f0aa0c6322 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1149,10 +1149,15 @@ struct rq { */ unsigned int nr_uninterruptible; +#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; @@ -1347,10 +1352,17 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); #define cpu_curr(cpu) (cpu_rq(cpu)->curr) #define raw_rq() raw_cpu_ptr(&runqueues) +#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 #ifdef CONFIG_SCHED_CORE static inline struct cpumask *sched_group_span(struct sched_group *sg); -- 2.49.0.604.gff1f9ca942-goog