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Date:   Wed, 4 Sep 2019 10:20:46 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Viktor Rosendahl <viktor.rosendahl@gmail.com>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH v5 1/4] ftrace: Implement fs notification for
 tracing_max_latency
Message-ID: <20190904082046.GB2349@hirez.programming.kicks-ass.net>
References: <20190903132602.3440-1-viktor.rosendahl@gmail.com>
 <20190903132602.3440-2-viktor.rosendahl@gmail.com>
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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.