Re: [PATCH v5 1/4] ftrace: Implement fs notification for tracing_max_latency

From: Peter Zijlstra
Date: Wed Sep 04 2019 - 04:20:53 EST

On Tue, Sep 03, 2019 at 03:25:59PM +0200, Viktor Rosendahl wrote:

> It seems like it would be possible to simply replace the calls to
> latency_fsnotify_enable/disable() with calls to
> start/stop_critical_timings(). However, the main problem is that it
> would not work for the wakup tracer. The wakeup tracer needs a
> facility that postpones the notifications, not one that prevents the
> measurements because all its measurements takes place in the middle
> of __schedule(). On the other hand, in some places, like in idle and
> the console we need start stop functions that prevents the
> measurements from being make.

Like Joel already mentioned; you can use irq_work here.