Thanks for clarifying this ! Steven. This is really helpful. Regards, Ze On Tue, Aug 1, 2023 at 10:33 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > On Tue, 1 Aug 2023 13:46:50 +0200 > Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > On Tue, Aug 01, 2023 at 05:01:22PM +0800, Ze Gao wrote: > > > Report priorities in 'short' and prev_state in 'int' to save > > > some buffer space. And also reorder the fields so that we take > > > struct alignment into consideration to make the record compact. > > > > > > Suggested-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> > > > > I don't see a single line describing the effort you've done to audit > > consumers of this tracepoint. > > > > *IF* you're wanting to break this tracepoint ABI, because seriously > > that's what it is, then you get to invest the time and effort to audit > > the users. > > The known major users that I am aware of is raesdaemon, > powertop/latencytop, perf, trace-cmd and some bpf tools. The bpf tooling is > known to update per kernel. The others all use libtraceevent that can > handle this change. > > What other tools are there? There's Perfetto, but it also looks at tracefs > to examine where the values are. There's LTTng, but I believe it uses the > raw tracepoint directly and doesn't look at the layout of the ftrace/perf > buffers. > > All other tooling I am slightly aware of uses libtracefs and libtraceveent, > as I've been giving many talks on how to use those libraries. > > -- Steve
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