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d4318c1a79
PCIe link speed degradation directly impacts system performance and often
indicates hardware issues such as faulty devices, physical layer problems,
or configuration errors.
To this end, add a RAS tracepoint to monitor link speed changes, enabling
proactive health checks and diagnostic analysis.
The following output is generated when a device is hotplugged:
$ echo 1 > /sys/kernel/debug/tracing/events/pci/pcie_link_event/enable
$ 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
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Suggested-by: Matthew W Carlis <mattc@purestorage.com>
Suggested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20251210132907.58799-3-xueshuai@linux.alibaba.com