Hi Christophe and Kienan,
Internal On 12/2/24 4:17 PM, Christophe Bédard via lttng-dev wrote: > I did the same thing a while ago, i.e., trigger tracepoints on > malloc/free/etc. using liblttng-ust-libc-wrapper and collect userspace > callstack information (so that the indirect calls to malloc/free can be > removed from an application). > ... Thank you for the information and links! I have looked into it, seems promising. On 12/10/24 11:41 AM, Kienan Stewart via lttng-dev wrote: > Depending on the type of information you require, it could be possible > to use the instruction-pointer (ip) context[1], the statedump[2] and/or > lttng-ust-dl[3] for base addresses, and the symbol table in-order to > resolve ip -> symbol name in the offline analysis phase with the help of > babeltrace's debug-info plugin[4]. While a bit more work for the > analysis, this process reduces the impact of the tracing on the program > at run-time. Thanks for the hints. This would be possible, but that would give me only the instruction pointer of the top-level stack frame. If malloc and free calls are wrapped inside of functions (e.g. think about std::string, std::unique/shared_ptr for C++), I would only see that it's called from that specific type. But, for me, it's important to see the context, too, where the string/smart pointer is used. Therefore I want to record the instruction pointer of every stackframe (or at least the top N ones in order to be able to locate the "problem"). As stacktraces are only wanted/needed for specific events, I also consider adding new tracepoints like lttng_ust_libc:malloc_stacktrace to lttng-ust-libc-wrapper directly recording the desired information into the trace buffer as an alternative solution. Best regards, Alexander
