linux-kernel - Re: [resend PATCH for 3.2] procfs: do not confuse jiffies with cputime64

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Message-ID: <m2wr9o52pv.fsf@igel.home>
Date:	Thu, 22 Dec 2011 11:18:36 +0100
From:	Andreas Schwab <schwab@...ux-m68k.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Michal Hocko <mhocko@...e.cz>, Arnd Bergmann <arnd@...db.de>,
	linux-kernel@...r.kernel.org,
	"Artem S. Tashkinov" <t.artem@...lcity.com>,
	Dave Jones <davej@...hat.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: [resend PATCH for 3.2] procfs: do not confuse jiffies with cputime64_t

Andrew Morton <akpm@...ux-foundation.org> writes:

> On Thu, 22 Dec 2011 01:14:39 +0100
> Andreas Schwab <schwab@...ux-m68k.org> wrote:
>
>> > a) what effect does this problem have upon users of the kernel?
>> 
>> get_idle_time returns the value in the wrong unit.
>
> So the "idle" fields in /proc/stat are wrong.
>
> We're getting there!  Now, in what way are they wrong?

They use the wrong unit, off by the factor between jiffies and cputime.

> How could a kernel maintainer recognise that this patch is needed?

By running the kernel on one of the architectures that are affected (did
I already say that on most architectures jiffies and cputime are
equivalent?).

Andreas.

-- 
Andreas Schwab, schwab@...ux-m68k.org
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