linux-kernel - Re: [PATCH 2/2] tracing: Add support for critical section events

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Message-ID: <CAJWu+opzANvRKkoyVxCtpNgV8HbVARVLQWtfjfdbCV4rjZyW_g@mail.gmail.com>
Date:   Mon, 4 Sep 2017 20:26:13 -0700
From:   Joel Fernandes <joelaf@...gle.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel-team@...roid.com,
        Ingo Molnar <mingo@...hat.com>,
        Byungchul Park <byungchul.park@....com>,
        Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 2/2] tracing: Add support for critical section events

On Mon, Sep 4, 2017 at 5:54 PM, Joel Fernandes <joelaf@...gle.com> wrote:
> On Mon, Sep 4, 2017 at 4:34 PM, Steven Rostedt <rostedt@...dmis.org> wrote:
>> On Mon, 4 Sep 2017 21:44:26 +0200
>> Peter Zijlstra <peterz@...radead.org> wrote:
>>
>>> > I can change the name to something else, but at the moment I can't
>>> > think of anything better. Could you suggest a better name? Also btw,
>>> > 'critical timings' is the terminology used within the irqsoff tracer
>>> > so this is in line with that.
>>>
>>> So 'critical section' is what some mis-guided people call the locked
>>> region of a lock :-) Using it for something else is prone to cause more
>>> confusion...
>>>
>>> I would simply call them what they are: irq_disable,irq_enable
>>> preempt_disable,preempt_enable.
>>
>> Yes please. The "critical section" naming came from the code that was
>> from the latency tracer days of the real time patch (pre-ftrace). The
>> irqsoff tracer has the least modification from the original code, and
>> probably should be rewritten one of these days.
>
> Sounds good to me. For the subsystem, could you guys suggest a name? I
> was thinking "atomic_section"?
>
> Something like:
>
> subsystem: atomic_section
> events:
>   irqsoff_disable
>   irqsoff_enable
>   preemptoff_disable
>   preemptoff_enable
>
> and additionally (to do what my patch does):
>   preemptirqsoff_enable
>   preemptirqsoff_disable

Apologies, I meant (without the "off"):

subsystem: atomic_section
events:
  irqs_disable
  irqs_enable
  preempt_disable
  preempt_enable

and additionally (similar to what my patch does):
  preemptirq_enable
  preemptirq_disable


Could you let me know if we are in agreement about this naming?

thanks,

-Joel