linux-kernel - Re: [tip:sched/core] sched/cputime: Refactor the cputime

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Date:   Tue, 4 Jul 2017 12:01:29 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     fransklaver@...il.com, hpa@...or.com, fweisbec@...il.com,
        torvalds@...ux-foundation.org, riel@...hat.com, tglx@...utronix.de,
        wanpeng.li@...mail.com, linux-kernel@...r.kernel.org,
        garsilva@...eddedor.com, sgruszka@...hat.com,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:sched/core] sched/cputime: Refactor the cputime_adjust()
 code


* Peter Zijlstra <peterz@...radead.org> wrote:

> Argh, no... That code was perfectly fine. The new code otoh is
> convoluted crap.
> 
> It had the form:
> 
> 	if (exception1)
> 	  deal with exception1
> 
> 	if (execption2)
> 	  deal with exception2
> 
> 	do normal stuff
> 
> Which is as simple and straight forward as it gets.
> 
> The new code otoh reads like:
> 
> 	if (!exception1) {
> 		if (exception2)
> 		  deal with exception 2
> 		else
> 		  do normal stuff
> 	}
> 
> which is absolute shit.
> 
> So NAK on this.

Agreed - I've queued up a revert.

Note that I fixed the old comment, which was arguably wrong:

	/*
	 * If either stime or both stime and utime are 0, assume all runtime is
	 * userspace. Once a task gets some ticks, the monotonicy code at
	 * 'update' will ensure things converge to the observed ratio.
	 */

The correct comment is something like:

	/*
	 * If either stime or utime are 0, assume all runtime is userspace.
	 * Once a task gets some ticks, the monotonicy code at 'update:'
	 * will ensure things converge to the observed ratio.
	 */

Thanks,

	Ingo