From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-100.freemail.mail.aliyun.com (out30-100.freemail.mail.aliyun.com [115.124.30.100]) (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 BA1952D7DC3; Wed, 10 Dec 2025 13:45:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.100 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765374317; cv=none; b=tCGcdIoPJHb9ZgQBmYtQTU7XQPOboMSlp37yfOLQScAbpY9kpaJ5hDPI5RD0zEFdWXZ2l8vhwTVJIwqB15CipbU8YFw8qRwikDa5SFUgFEa9rf1xNixQgK+NX6haKfl4R9jhK7EHcLnmUkMvdDuI8exC5hryOC94iJsV8Gly48M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765374317; c=relaxed/simple; bh=8igfRfc51/I57E16VjrR1S+jVMd5sGrfunrFvM2KX6Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=SndUQ3mRqguR5utAjL77AOGtixgBX+qrTnsGEBt3MX3rgf21bh2ah3CsyMb+svmhSSKTYuvIvWGbXAJSXqcJ2XWtMQlWfTMUB173ZM1XJPqPXEDD5/39wQNf1dIyOxd75GN5qHCq3cfqa2C7RswK/QnzcMzJuWxeoyE+K7blJ98= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=Tmt8PmUd; arc=none smtp.client-ip=115.124.30.100 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="Tmt8PmUd" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1765374303; h=From:To:Subject:Date:Message-Id:MIME-Version:Content-Type; bh=gzPsh3DxNKuFK2BEt2GcqSOyPks+CU4OAD5uGgR0UFA=; b=Tmt8PmUdLiZTYkc0Wluly67YpUPiNXfyA9XM2TtwE8QJNSY+VQgKdcnPIOepe5ibGAYDoGWqpfNZfd7M3b+9TBCKOo0jSvrURbh7VC2DQVY90xb51S89kyEWlM3PhCgGlOXlaOKOe4IzeLKTsQiIXsZqBHSXbdb/FG6847tVqjc= Received: from localhost.localdomain(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WuWtM64_1765373352 cluster:ay36) by smtp.aliyun-inc.com; Wed, 10 Dec 2025 21:29:13 +0800 From: Shuai Xue To: rostedt@goodmis.org, lukas@wunner.de, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-trace-kernel@vger.kernel.org, helgaas@kernel.org, ilpo.jarvinen@linux.intel.com, mattc@purestorage.com, Jonathan.Cameron@huawei.com, alok.a.tiwari@oracle.com Cc: bhelgaas@google.com, tony.luck@intel.com, bp@alien8.de, xueshuai@linux.alibaba.com, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, oleg@redhat.com, naveen@kernel.org, davem@davemloft.net, anil.s.keshavamurthy@intel.com, mark.rutland@arm.com, peterz@infradead.org, tianruidong@linux.alibaba.com Subject: [PATCH v14 3/3] Documentation: tracing: Add documentation about PCI tracepoints Date: Wed, 10 Dec 2025 21:29:07 +0800 Message-Id: <20251210132907.58799-4-xueshuai@linux.alibaba.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20251210132907.58799-1-xueshuai@linux.alibaba.com> References: <20251210132907.58799-1-xueshuai@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The PCI tracing system provides tracepoints to monitor critical hardware events that can impact system performance and reliability. Add documentation about it. Reviewed-by: Ilpo Järvinen Signed-off-by: Shuai Xue --- Documentation/trace/events-pci.rst | 74 ++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 Documentation/trace/events-pci.rst diff --git a/Documentation/trace/events-pci.rst b/Documentation/trace/events-pci.rst new file mode 100644 index 000000000000..b9f7a9edee35 --- /dev/null +++ b/Documentation/trace/events-pci.rst @@ -0,0 +1,74 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================== +Subsystem Trace Points: PCI +=========================== + +Overview +======== +The PCI tracing system provides tracepoints to monitor critical hardware events +that can impact system performance and reliability. These events normally show +up here: + + /sys/kernel/tracing/events/pci + +Cf. include/trace/events/pci.h for the events definitions. + +Available Tracepoints +===================== + +pci_hp_event +------------ + +Monitors PCI hotplug events including card insertion/removal and link +state changes. +:: + + pci_hp_event "%s slot:%s, event:%s\n" + +**Event Types**: + +* ``LINK_UP`` - PCIe link established +* ``LINK_DOWN`` - PCIe link lost +* ``CARD_PRESENT`` - Card detected in slot +* ``CARD_NOT_PRESENT`` - Card removed from slot + +**Example Usage**: + + # Enable the tracepoint + echo 1 > /sys/kernel/debug/tracing/events/pci/pci_hp_event/enable + + # Monitor events (the following output is generated when a device is hotplugged) + cat /sys/kernel/debug/tracing/trace_pipe + irq/51-pciehp-88 [001] ..... 1311.177459: pci_hp_event: 0000:00:02.0 slot:10, event:CARD_PRESENT + + irq/51-pciehp-88 [001] ..... 1311.177566: pci_hp_event: 0000:00:02.0 slot:10, event:LINK_UP + +pcie_link_event +--------------- + +Monitors PCIe link speed changes and provides detailed link status information. +:: + + pcie_link_event "%s type:%d, reason:%d, cur_bus_speed:%d, max_bus_speed:%d, width:%u, flit_mode:%u, status:%s\n" + +**Parameters**: + +* ``type`` - PCIe device type (4=Root Port, etc.) +* ``reason`` - Reason for link change: + + - ``0`` - Link retrain + - ``1`` - Bus enumeration + - ``2`` - Bandwidth notification enable + - ``3`` - Bandwidth notification IRQ + - ``4`` - Hotplug event + + +**Example Usage**: + + # Enable the tracepoint + echo1 > /sys/kernel/debug/tracing/events/pci/pcie_link_event/enable + + # Monitor events (the following output is generated when a device is hotplugged) + cat /sys/kernel/debug/tracing/trace_pipe + irq/51-pciehp-88 [001] ..... 381.545386: pcie_link_event: 0000:00:02.0 type:4, reason:4, cur_bus_speed:20, max_bus_speed:23, width:1, flit_mode:0, status:DLLLA -- 2.39.3