Call stack context for user space trace points

Call stack context for user space trace points

[Sunku, Sai via lttng-dev]

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Hello,

I have a complex, multithreaded benchmark that emits LTTng trace points at various stages. I am trying to trace all malloc calls made by this benchmark. I'm specifically trying to get malloc trace points also through LTTng so that I can identify when the malloc call was made relative to other trace points from the benchmark. I also want to see the stack trace for each malloc call so that I can identify where in the benchmark the malloc call is coming from.

If I preload the lttng libc wrapper with `LD_PRELOAD=liblttng-ust-libc-wrapper.so`, I'm able to see the trace points from malloc calls.

But when I try to add the callstack-user context with this command `lttng add-context --userspace --channel 1 --type callstack-user`, I get an error saying "Error: callstack-user: UST invalid context"

I've successfully added user space stack traces for kernel trace points with a similar command `lttng add-context --kernel --type callstack-user`

Is the callstack-user context only available for kernel trace points? Is there another way to get the call stack for malloc calls?

Thank you,
Sai Sunku


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Re: Call stack context for user space trace points

[Christophe Bédard via lttng-dev]

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Hi,

The userspace callstack context is only available for the kernel domain.

There are potential workarounds and solutions; take a look at the
discussion in this mailing list thread from last year (hit "Next message"):
https://lists.lttng.org/pipermail/lttng-dev/2024-December/030881.html

Regards,

Christophe

On Mon, Oct 6, 2025 at 5:37 AM Sunku, Sai via lttng-dev <
lttng-dev@lists.lttng.org> wrote:

> Hello,
>
>
>
> I have a complex, multithreaded benchmark that emits LTTng trace points at
> various stages. I am trying to trace all malloc calls made by this
> benchmark. I'm specifically trying to get malloc trace points also through
> LTTng so that I can identify when the malloc call was made relative to
> other trace points from the benchmark. I also want to see the stack trace
> for each malloc call so that I can identify where in the benchmark the
> malloc call is coming from.
>
>
>
> If I preload the lttng libc wrapper with
> `LD_PRELOAD=liblttng-ust-libc-wrapper.so`, I'm able to see the trace points
> from malloc calls.
>
>
>
> But when I try to add the callstack-user context with this command `lttng
> add-context --userspace --channel 1 --type callstack-user`, I get an error
> saying "Error: callstack-user: UST invalid context"
>
>
>
> I've successfully added user space stack traces for kernel trace points
> with a similar command `lttng add-context --kernel --type callstack-user`
>
>
>
> Is the callstack-user context only available for kernel trace points? Is
> there another way to get the call stack for malloc calls?
>
>
>
> Thank you,
>
> Sai Sunku
>
>
>

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