Re: [PATCH] x86: fix get_wchan() not support the ORC unwinder

[Andy Lutomirski]

On 6/11/21 5:46 AM, Qi Zheng wrote:
> Currently, the kernel CONFIG_UNWINDER_ORC option is enabled by
> default on x86, but the implementation of get_wchan() is still
> based on the frame pointer unwinder, so the /proc/<pid>/wchan
> always return 0 regardless of whether the task <pid> is running.
> 
> We reimplement the get_wchan() by calling stack_trace_save_tsk(),
> which is adapted to the ORC and frame pointer unwinders.

How much slower does this make ps?

--Andy