On Fri, 9 Jan 2026 17:33:26 -0500 Steven Rostedt <[email protected]> wrote:
> How is this about lttng? Sure he cares about that, but even tracepoints > that lttng uses doesn't get affected any more than ftrace or bpf. > Because lttng is one of the callbacks. The migrate disable happens in > the in-tree portion of the code. > > So you are saying that all the tracepoints for xfs are not in a fastpath? Regardless of tracing. I now have my RT hat on. The spin_locks that are converted to mutex use migrate disable. The fact that migrate_disable in modules are close to 10x slower than the same code in-kernel is troubling to say the least. It means that modules in RT take a hit every time they take a spin_lock(). The migrate disable being slow for modules is no longer just a tracing issue. It's a PREEMPT_RT issue. -- Steve
