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

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Message-ID: <m2vcp9o3rz.fsf@igel.home>
Date:	Thu, 22 Dec 2011 01:20:48 +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 00:55:07 +0100
> Andreas Schwab <schwab@...ux-m68k.org> wrote:
>
>> Andrew Morton <akpm@...ux-foundation.org> writes:
>> 
>> > Also, in include/asm-generic/cputime.h we have:
>> >
>> > #define usecs_to_cputime64(__msecs)	nsecs_to_jiffies64((__msecs) * 1000)
>> >
>> > But it would be neater to have used nsecs_to_cputime64(), surely.
>> 
>> The procfs interface wants to convert usecs to cputime64, but generic
>> cputime does not have usecs_to_jiffies64.  Once someone writes the
>> latter it can be used here.
>> 
>
> That doesn't address my suggestion.
>
> I'm saying that this:
>
> #define usecs_to_cputime64(__msecs)	nsecs_to_jiffies64((__msecs) * 1000)
>
> should have instead been
>
> #define usecs_to_cputime64(__msecs)	nsecs_to_cputime64((__msecs) * 1000)

It follows the style of the exitsting definitions.  Generic cputime does
not differentiate between jiffies and cputime, so adding a layer of
indirection only here does not increase clarity, IMHO.

Andreas.

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