Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast

[Steven Rostedt]

On Fri, 9 Jan 2026 13:54:34 -0800
Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote:

> On Fri, Jan 9, 2026 at 12:21 PM Mathieu Desnoyers
> <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
> >
> >
> > * preempt disable/enable pair:                                     1.1 ns
> > * srcu-fast lock/unlock:                                           1.5 ns
> >
> > CONFIG_RCU_REF_SCALE_TEST=y
> > * migrate disable/enable pair:                                     3.0 ns  
> 
> .. and you're arguing that 3ns vs 1ns difference is so important
> for your out-of-tree tracer that in-tree tracers need to do
> some workarounds?! wtf

This has nothing to do with out of tree tracers. The overhead of the
22ns is for any tracepoint in an in-tree module. That's because the
rq->nr_pinned isn't exported for modules to use.

-- Steve