linux-kernel - Re: [PATCH 11/16] sched: add latency tracing for -deadline tasks.

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Date:	Mon, 16 Apr 2012 17:51:22 +0200
From:	Daniel Vacek <neelx.g@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Juri Lelli <juri.lelli@...il.com>, peterz@...radead.org,
	tglx@...utronix.de, mingo@...hat.com, cfriesen@...tel.com,
	oleg@...hat.com, fweisbec@...il.com, darren@...art.com,
	johan.eker@...csson.com, p.faure@...tech.ch,
	linux-kernel@...r.kernel.org, claudio@...dence.eu.com,
	raistlin@...ux.it
Subject: Re: [PATCH 11/16] sched: add latency tracing for -deadline tasks.

Hi,

On Wed, Apr 11, 2012 at 23:03, Steven Rostedt <rostedt@...dmis.org> wrote:
>> +     /*
>> +      * Semantic is like this:
>> +      *  - wakeup tracer handles all tasks in the system, independently
>> +      *    from their scheduling class;
>> +      *  - wakeup_rt tracer handles tasks belonging to sched_dl and
>> +      *    sched_rt class;
>> +      *  - wakeup_dl handles tasks belonging to sched_dl class only.
>> +      */
>> +     if ((wakeup_dl && !dl_task(p)) ||
>> +         (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
>> +         (p->prio >= wakeup_prio || p->prio >= current->prio))
>>               return;
>
> Anyway, perhaps this should be broken up, as we don't want the double
> test, that is, wakeup_rt and wakeup_dl are both checked. Perhaps do:
>
>        if (wakeup_dl && !dl_task(p))
>                return;
>        else if (wakeup_rt && !dl_task(p) && !rt_task(p))
>                return;
>
>        if (p->prio >= wakeup_prio || p->prio >= current->prio)
>                return;
>
>
> -- Steve

sorry for the question, I'm obviously missing something here but what
is the logic behind this rewrite? In both cases my gcc generates the
same code for me.

nX
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