Re: [PATCH v12 3/3] Documentation: tracing: Add documentation about PCI tracepoints

Shuai Xue
2025-10-15T02:36:51Z

在 2025/10/14 22:40, Ilpo Järvinen 写道:
> On Tue, 14 Oct 2025, Shuai Xue wrote:
>
>> The PCI tracing system provides tracepoints to monitor critical hardware
>> events that can impact system performance and reliability. Add
>> documentation about it.
>>
>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>> ---
>> 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..500b27713224
>> --- /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:%s, max_bus_speed:%s, 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 controller enable
>> + - ``3`` - Bandwidth controller IRQ
>
> Maybe these two should be called "Bandwidth notification" as that's the
> name of the underlying mechanism.

Sure, I will rename it.

>
> For the entire series,
>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Thanks.

Best Regards,
Shuai