From patchwork Thu Feb 6 08:09:46 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gabriele Monaco X-Patchwork-Id: 13962593 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7473C225799 for ; Thu, 6 Feb 2025 08:10:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738829447; cv=none; b=iWtEZePdA1rkpw9M5eafXWPR9AUTJpF/7SKQveCjS9KNvd9yPScb/0pCZJVQpfat35xvE64thwya0LSC+Q7mKiuw6DlEtPWdRyY/fwQrKGWti6x3wOQCNxH7e4SCv+Am8JAsCdVCjl2NKh5Wgk8Xn9rmbGiEOgMHTEZgdx5j48I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738829447; c=relaxed/simple; bh=IY7DU1BhjQRR5Coi7wNZ7++4LSEJz4/d+wLFVatOJNE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nF+XwOqZTHpxTXg9QyeNmoZSDq3ltehcObGTvn3yi7jiPAvEeRyBMS33RhA5B9xHlF3AOB0nf1Mu7FkggKhtt34zCllLQdJ6Oob7EiOZraNuTn5ARp7xjXM4gmPlz1K/OhGrsfPGnnXLmBsVhe9yfc0eZia5dd6DA7tcZE44Bws= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Pz6V4cRG; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Pz6V4cRG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1738829444; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rPPwrQnu9UKt/4NbsUXxMh/AuN498RxwAC9aj1izwuk=; b=Pz6V4cRGaCL9qocbY/L7du0sHKeW/Rv1jWEmR2BL24VgaJiwkvH7lASCe31T77/a2WCbf8 P0Qqn9GO0Kqjvf6Hh2d43KntzBMfHNEmPyY8LvA/uUSoEAIxjW2/t0pF2YFdRypOicE14c KSMXSFcuZaqbDfogV/UXGeoCYoF7yPw= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-608-fiP22780PDCosPesVr3YzA-1; Thu, 06 Feb 2025 03:10:41 -0500 X-MC-Unique: fiP22780PDCosPesVr3YzA-1 X-Mimecast-MFC-AGG-ID: fiP22780PDCosPesVr3YzA Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2A17B1956059; Thu, 6 Feb 2025 08:10:40 +0000 (UTC) Received: from gmonaco-thinkpadt14gen3.rmtit.com (unknown [10.45.224.82]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 436AD19560B9; Thu, 6 Feb 2025 08:10:35 +0000 (UTC) From: Gabriele Monaco To: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Jonathan Corbet , Steven Rostedt , linux-doc@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Gabriele Monaco , Juri Lelli , John Kacur , Clark Williams Subject: [RFC PATCH 10/11] Documentation/rv: Add docs for the sched monitors Date: Thu, 6 Feb 2025 09:09:46 +0100 Message-ID: <20250206080952.98478-11-gmonaco@redhat.com> In-Reply-To: <20250206080952.98478-1-gmonaco@redhat.com> References: <20250206080952.98478-1-gmonaco@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Add man page and kernel documentation for the sched monitors, as sched is a container of other monitors, document all in the same page. sched is the first nested monitor, also explain what is a nested monitor and how enabling containers or children monitors work. To: Ingo Molnar To: Peter Zijlstra Cc: Juri Lelli Cc: John Kacur Cc: Clark Williams Signed-off-by: Gabriele Monaco --- Documentation/tools/rv/rv-mon-sched.rst | 69 +++++++++ Documentation/trace/rv/monitor_sched.rst | 171 +++++++++++++++++++++++ 2 files changed, 240 insertions(+) create mode 100644 Documentation/tools/rv/rv-mon-sched.rst create mode 100644 Documentation/trace/rv/monitor_sched.rst diff --git a/Documentation/tools/rv/rv-mon-sched.rst b/Documentation/tools/rv/rv-mon-sched.rst new file mode 100644 index 0000000000000..da0fe4c79ae52 --- /dev/null +++ b/Documentation/tools/rv/rv-mon-sched.rst @@ -0,0 +1,69 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +rv-mon-sched +============ +----------------------------- +Scheduler monitors collection +----------------------------- + +:Manual section: 1 + +SYNOPSIS +======== + +**rv mon sched** [*OPTIONS*] + +**rv mon ** [*OPTIONS*] + +**rv mon sched:** [*OPTIONS*] + +DESCRIPTION +=========== + +The scheduler monitor collection is a container for several monitors to model +the behaviour of the scheduler. Each monitor describes a specification that +the scheduler should follow. + +As a monitor container, it will enable all nested monitors and set them +according to OPTIONS. +Nevertheless nested monitors can also be activated independently both by name +and by specifying sched: , e.g. to enable only monitor tss you can do any of: + + # rv mon sched:tss + + # rv mon tss + +See kernel documentation for further information about this monitor: + + +OPTIONS +======= + +.. include:: common_ikm.rst + +NESTED MONITOR +============== + +The available nested monitors are: + * scpd: schedule called with preemption disabled + * snep: schedule does not enable preempt + * sncid: schedule not called with interrupt disabled + * snroc: set non runnable on its own context + * sco: scheduling context operations + * tss: task switch while scheduling + +SEE ALSO +======== + +**rv**\(1), **rv-mon**\(1) + +Linux kernel *RV* documentation: + + +AUTHOR +====== + +Written by Gabriele Monaco + +.. include:: common_appendix.rst diff --git a/Documentation/trace/rv/monitor_sched.rst b/Documentation/trace/rv/monitor_sched.rst new file mode 100644 index 0000000000000..24b2c62a3bc26 --- /dev/null +++ b/Documentation/trace/rv/monitor_sched.rst @@ -0,0 +1,171 @@ +Scheduler monitors +================== + +- Name: sched +- Type: container for multiple monitors +- Author: Gabriele Monaco , Daniel Bristot de Oliveira + +Description +----------- + +Monitors describing complex systems, such as the scheduler, can easily grow to +the point where they are just hard to understand because of the many possible +state transitions. +Often it is possible to break such descriptions into smaller monitors, +sharing some or all events. Enabling those smaller monitors concurrently is, +in fact, testing the system as if we had one single larger monitor. +Splitting models into multiple specification is not only easier to +understand, but gives some more clues when we see errors. + +The sched monitor is a set of specifications to describe the scheduler behaviour. +It includes several per-cpu and per-task monitors that work independently to verify +different specifications the scheduler should follow. + +To make this system as straightforward as possible, sched specifications are *nested* +monitors, whereas sched itself is a *container*. +From the interface perspective, sched includes other monitors as sub-directories, +enabling/disabling or setting reactors to sched, propagates the change to all monitors, +however single monitors can be used independently as well. + +It is important that future modules are built after their container (sched, in +this case), otherwise the linker would not respect the order and the nesting +wouldn't work as expected. +To do so, simply add them after sched in the Makefile. + +Specifications +-------------- + +The specifications included in sched are currently a work in progress, adapting the ones +defined in by Daniel Bristot in [1]. + +Currently we included the following: + +Monitor tss +~~~~~~~~~~~ + +The task switch while scheduling (tss) monitor ensures a task switch happens +only in scheduling context, that is inside a call to `__schedule`:: + + | + | + v + +-----------------+ + | thread | <+ + +-----------------+ | + | | + | schedule_entry | schedule_exit + v | + sched_switch | + +--------------- | + | sched | + +--------------> -+ + +Monitor sco +~~~~~~~~~~~ + +The scheduling context operations (sco) monitor ensures changes in a task state +happen only in thread context:: + + + | + | + v + sched_set_state +------------------+ + +------------------ | | + | | thread_context | + +-----------------> | | <+ + +------------------+ | + | | + | schedule_entry | schedule_exit + v | + | + scheduling_context -+ + +Monitor snroc +~~~~~~~~~~~~~ + +The set non runnable on its own context (snroc) monitor ensures changes in a +task state happens only in the respective task's context. This is a per-task +monitor:: + + | + | + v + +------------------+ + | other_context | <+ + +------------------+ | + | | + | sched_switch_in | sched_switch_out + v | + sched_set_state | + +------------------ | + | own_context | + +-----------------> -+ + +Monitor scpd +~~~~~~~~~~~~ + +The schedule called with preemption disabled (scpd) monitor ensures schedule is +called with preemption disabled:: + + | + | + v + +------------------+ + | cant_sched | <+ + +------------------+ | + | | + | preempt_disable | preempt_enable + v | + schedule_entry | + schedule_exit | + +----------------- can_sched | + | | + +----------------> -+ + +Monitor snep +~~~~~~~~~~~~ + +The schedule does not enable preempt (snep) monitor ensures a schedule call +does not enable preemption:: + + | + | + v + preempt_disable +------------------------+ + preempt_enable | | + +------------------ | non_scheduling_context | + | | | + +-----------------> | | <+ + +------------------------+ | + | | + | schedule_entry | schedule_exit + v | + | + scheduling_contex -+ + +Monitor sncid +~~~~~~~~~~~~~ + +The schedule not called with interrupt disabled (sncid) monitor ensures +schedule is not called with interrupt disabled:: + + | + | + v + schedule_entry +--------------+ + schedule_exit | | + +----------------- | can_sched | + | | | + +----------------> | | <+ + +--------------+ | + | | + | irq_disable | irq_enable + v | + | + cant_sched -+ + +References +---------- + +[1] - https://bristot.me/linux-task-model