linux-kernel - Re: [PATCH v5 1/4] ftrace: Implement fs notification for tracing_max

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Message-ID: <20190904073734.0a70236c@oasis.local.home>
Date:   Wed, 4 Sep 2019 07:37:34 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Viktor Rosendahl <viktor.rosendahl@...il.com>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Joel Fernandes <joel@...lfernandes.org>
Subject: Re: [PATCH v5 1/4] ftrace: Implement fs notification for
 tracing_max_latency

On Wed, 4 Sep 2019 10:20:46 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> 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.

And I was thinking the exact same thing here too ;-)

-- Steve