From nobody Sat Feb 7 11:56:30 2026 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 4D2A917E00F for ; Mon, 25 Nov 2024 19:52:09 +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=1732564330; cv=none; b=Uzn5FUgqR9ht7snfVxvh+raERiqBXusd8OocZfphTnXaelsK1Zd56r2hraiEi3bIVuGcBVyyC01pwr+q/yq22bKdIXifnmpDiHs9+PHqtX7xLip2VpqYkzP6g8kxpUQ1OQ9LvrkngVFyfhjuQ6PfR9XGHz/P2GQ16KtaKqiIXic= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732564330; c=relaxed/simple; bh=ldvGcJ1p5BFMj5Gb5T1BYJE899OrjpqU47w++MQHuO8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=T+4NKM51BmWTK/3CfQtiDEs7TPjkHX4EcyrOnTXo1TbugNZrkZr0Ai6LsKIb32Y1ZEsA5upoq43zGCd0epKAtd1CCyxwuhJOsjK+cVmH71yLvyE+HJZI2RmGfuJOPsKrotam7LsDHnpOC88UicWxfv0agJCPKHfge4/R5S5+juU= 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=lwAlyHF4; 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="lwAlyHF4" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-7fbbb61a67cso3222028a12.3 for ; Mon, 25 Nov 2024 11:52:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1732564328; x=1733169128; 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=Ajms8VnNMkE1TQffsMnBvZtTPD6SPlAUmat2ZJ1/s7g=; b=lwAlyHF4ThPqLryoC6TccNW3ICNct0LQTa+m1NQTmWdm5thNa82mtGBeDrNWq33K7u /1jS3xkVW4zmfB5IbVKgo28ItHOCmsXhMU7MYllTE9MfzmRNSU7ggCBK3MZa1P6z4sIl IkwfWtbmM27nUccKdFTPJM67/DM0Bdki5cdjjhLOA5+4ykUXklBPsxqQblgou01B9eYs Bj2s2vxHbzzZrKr7OtJdR8Xvi/pLLKHpSFmUxkO5eG5lRJmmiBmHLqipqWV9H3D7jiys +Cfb1mVgG74KUirqV2d50kBcKP1vuiKHfQ/Zmz9P/TR8I4USJ0sgdrCCW+0bNs1afpnR dDtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732564328; x=1733169128; 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=Ajms8VnNMkE1TQffsMnBvZtTPD6SPlAUmat2ZJ1/s7g=; b=P+JlFdW6EoFXFwvIANcgUUezWa65WfA1soWz3IpC4T4JKAr+R8bwnX+gIWRzJwbMhW 2c9UhC2zDcFntT1Ke4aH3Vw+e9pU26I0mt57GbqnFJb5ModsdYEaUcMeixwNWTR4hqnN eP4wj/2H8EKUCOK4BcY1T1uhKq2FQ4W5JJ7iQKWZWeDc5UBJkeXha+bsLX9r8engG22T X/USqpsz5yI3L7ziqoN9ewr3YQU8OF+hyZkzQwT3VV1/Sq3z7OL3DVfzpDZIVbJ3yyHo dn3jIizty6l0HXPBkEJdVP3PePMD4qAGWpo6fEevGwAOMTDQeje2fl04I9rpLjrc2zPb pInQ== X-Gm-Message-State: AOJu0YzjWcae6TMxUspddtd5ehCq3QY3IjybTTGu4mOwzHyDlFnhom7U QYd+NUNeYeh4wNVlIqEufifooka2wIHxlDKaAN0ru2ebHkKRPMz/WLwClqbW7MMQcRc1mvM4Kxs s8BBUftBHZmLDauY6gZB98NWecymFpde/IE9Vk+j1LgvCLxODQQcLzxIZ1SlLCS2ozaxU+EBv9i bA4ReYM7xDPd4+JePD9ObChsAH5rNg5jX4nJBMe9X+Y3kH X-Google-Smtp-Source: AGHT+IFRW2wpYU0GwI7l0UB+J3wwg1ogfMsLSpZ+RMNEClBjAmofPmgplJSoSqIM/qfIAJxIjEQWZMqYOpYr X-Received: from pgbee13.prod.google.com ([2002:a05:6a02:458d:b0:7fc:3112:b331]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:164a:b0:1e0:c5f9:75a0 with SMTP id adf61e73a8af0-1e0c5f977dbmr8796928637.17.1732564328450; Mon, 25 Nov 2024 11:52:08 -0800 (PST) Date: Mon, 25 Nov 2024 11:51:55 -0800 In-Reply-To: <20241125195204.2374458-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241125195204.2374458-1-jstultz@google.com> X-Mailer: git-send-email 2.47.0.371.ga323438b13-goog Message-ID: <20241125195204.2374458-2-jstultz@google.com> Subject: [RFC][PATCH v14 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 , 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. 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: kernel-team@android.com 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 --- .../admin-guide/kernel-parameters.txt | 5 ++++ include/linux/sched.h | 13 +++++++++ init/Kconfig | 9 ++++++ kernel/sched/core.c | 29 +++++++++++++++++++ kernel/sched/sched.h | 12 ++++++++ 5 files changed, 68 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index a4736ee87b1aa..761e858c62b92 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5955,6 +5955,11 @@ 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 f0e9e00d3cf52..24e338ac34d7b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1610,6 +1610,19 @@ struct task_struct { */ }; =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 b07f238f3badb..364bd2065b1f1 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -863,6 +863,15 @@ config UCLAMP_BUCKETS_COUNT =20 If in doubt, use the default value. =20 +config SCHED_PROXY_EXEC + bool "Proxy Execution" + default n + # Avoid some build failures w/ PREEMPT_RT until it can be fixed + depends on !PREEMPT_RT + 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 95e40895a5190..d712e177d3b75 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; + + if (kstrtobool(str, &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=3D", setup_proxy_exec); + #ifdef CONFIG_SCHED_DEBUG /* * Debugging: various feature bits diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 76f5f53a645fc..24eae02ddc7f6 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1148,10 +1148,15 @@ 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; @@ -1348,10 +1353,17 @@ 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 2.47.0.371.ga323438b13-goog