On Tue, Jul 01, 2025 at 07:26:19PM -0400, Steven Rostedt wrote:
On Tue, 1 Jul 2025 15:49:23 -0700 Kees Cook [off-list ref] wrote:
quoted
Okay, I've read the cover letter and this wiki page, but I am dense: why
does the _kernel_ want to do this? Shouldn't it only be userspace that
cares about userspace unwinding? I don't use perf, ftrace, and ebpf
enough to make this obvious to me, I guess. ;)
[...]
Anyway, yeah, it's something that has a ton of interest, as it's the way
for tools like perf to give nice graphs of where user space bottlenecks
exist.
Right! Yeah, I know it's very wanted -- I wasn't saying "don't this in
the kernel", but quite literally, "*I* am missing something about why
this is so important." :) And thank you, now I see: the sampling-based
profiling of userspace must happen via the kernel.
--
Kees Cook