Missing exceptions:page_fault_user event?

Missing exceptions:page_fault_user event?

[Trip Volpe]

Hey all; I'm trying to use `perf record` to get detailed information
about user page faults, including the addresses at which the faults
occurred. I've done this before with, e.g., `perf record -e
exceptions:page_fault_user -p 12345 sleep 1`.

However, on the system I'm examining now, I just get an "unknown
tracepoint" error. I checked
/sys/kernel/debug/tracing/events/exceptions, and sure enough, that
path does not exist. Does anybody happen to know under what
circumstances these tracepoints could be disabled or omitted? I've
looked through the kconfigs and sysctls for anything that might seem
relevant but have had no luck so far.

I'm running Ubuntu 16.04 with kernel 4.13 on a dual Xeon Gold 6126 system.

# uname -a
Linux test 4.13.0-37-generic #42~16.04.1 SMP Sat May 12 06:21:13 UTC
2018 x86_64 x86_64 x86_64 GNU/Linux

My kernel config is here: https://pastebin.com/raw/A62FDFd6

Any help or pointers would be greatly appreciated!

Re: Missing exceptions:page_fault_user event?

[Steven Rostedt]

On Mon, 26 Nov 2018 18:49:19 -0800
Trip Volpe <trip.volpe@gmail.com> wrote:

> Hey all; I'm trying to use `perf record` to get detailed information
> about user page faults, including the addresses at which the faults
> occurred. I've done this before with, e.g., `perf record -e
> exceptions:page_fault_user -p 12345 sleep 1`.
> 
> However, on the system I'm examining now, I just get an "unknown
> tracepoint" error. I checked
> /sys/kernel/debug/tracing/events/exceptions, and sure enough, that

I'm guessing that debugfs is mounted. What other event systems are
there?

 # ls /sys/kernel/debug/tracing/event

What does the above produce?

-- Steve


> path does not exist. Does anybody happen to know under what
> circumstances these tracepoints could be disabled or omitted? I've
> looked through the kconfigs and sysctls for anything that might seem
> relevant but have had no luck so far.
> 
> I'm running Ubuntu 16.04 with kernel 4.13 on a dual Xeon Gold 6126 system.
> 
> # uname -a
> Linux test 4.13.0-37-generic #42~16.04.1 SMP Sat May 12 06:21:13 UTC
> 2018 x86_64 x86_64 x86_64 GNU/Linux
> 
> My kernel config is here: https://pastebin.com/raw/A62FDFd6
> 
> Any help or pointers would be greatly appreciated!

Re: Missing exceptions:page_fault_user event?

[Steven Rostedt]

On Sun, 2 Dec 2018 13:33:34 -0800
Trip Volpe <trip.volpe@gmail.com> wrote:

> These tracepoints are still removed as of the latest Ubuntu 4.13 HWE
> kernel. I tried putting them back, and sure enough cratering ensued,
> so it looks like my best bet is to try moving forward to a newer
> kernel. Thanks for the help, Steve!

Thanks for the update.

-- Steve