On Thu, 12 Oct 2023 11:53:52 +0200 Daniel Vetter <daniel@xxxxxxxx> wrote: > > You said that turning the kernel ring buffer contents into strings is a > > very heavy operation, so it is not possible to push this scope > > separation to userspace, right? > > I think it's the kernel that does the formatting, but honestly not sure > how this works with perf traces. Might be that it's actually userspace > doing the formatting later on so that it doesn't incur the overhead while > recording. perf and trace-cmd do the formatting in user space via libtraceevent: git://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git It reads the format files of the events: /sys/kernel/tracing/events/*/*/format and uses that to read the raw data saved from the kernel into human readable output. Note, this means that addresses coming from kernel trace events are not hashed! -- Steve
