On Thu, Nov 22, 2018 at 07:46:05AM -0500, Steven Rostedt wrote: > On Thu, 22 Nov 2018 11:08:12 +0100 > Peter Zijlstra <pet...@infradead.org> wrote: > > > On Wed, Nov 21, 2018 at 08:27:08PM -0500, Steven Rostedt wrote: > > > Well the fuction graph tracer is arguably the strongest of the tracers. > > > It shows both the entrance and exit of a function, can give the timings > > > of a function, and shows the execution of the code quite nicely. > > > > > > But it has one major flaw. > > > > > > It can't let more than one user access it at a time. > > > > The reason I 'never' use it is performance, it _sucks_.. I've never ran > > into the multi-user issue. > > And performance is also something to fix (it has improved lately, you > probably haven't noticed).
Indeed, I've not recently used it. > > So while I don't think the rewrite is bad, this argument here is. > > Except that we plan on merging kretprobe with function graph tracing. > This also solves the issue that Mark Rutland has with ret protection. > He has a solution for function graph tracing, but not with kretprobes. Sure. But you didn't make that argument. > And yes, there's also the case of being able to trace to different > buffers where you can have a full function graph tracing enabled and > also trace a subset that you want to have. > > Just because you don't need it, doesn't mean it's not needed by others. Not saying that; just saying the argument doesn't hold. It is not the _one_ flaw.
