Re: trace events

[Marek Bykowski <marek.bykowski@gmail.com>]

On Fri, 18 Nov 2022 08:18:43 -0700
Dave Jiang <dave.jiang@intel.com> wrote:


> 
> Hi Marek. Have you looked into enabling ftrace? Maybe that would be
> the right starting point for what you are looking for?
> 
> https://lwn.net/Articles/365835/
> 

That was my initial idea but if there are no trace events defined for
the CXL what am I to enable? At least I cannot find any events for CXL,
there is no file include/trace/events/cxl.h in kernel/git/cxl/cxl.git.
Also

  find /sys/kernel/debug/tracing/events/ -name "*cxl*"

on linux-cxl returns nothing.

Alison mentioned she is working on some but these are yet in review.

As putting the trace events throughput the CXL driver/s takes time I
took a shortcut and added trace_printk scattered around for now. With
libtraceevent, trace-cmd and kernelshark and it is looking fantastic,
except it is not the CXL events as per-se.

root@localhost:~# trace-cmd show |tail -n 2
   systemd-udevd-520 [004] ..... 21.236650: devm_cxl_enumerate_decoders: \
			success adding decoder to port endpoint5
   systemd-udevd-520 [004] ..... 21.240517: devm_cxl_enumerate_ports.cold: \
			find_cxl_port() returned port port2