From: John Stultz <john.stultz@linaro.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Richard Cochran <richardcochran@gmail.com>,
Prarit Bhargava <prarit@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1/2] jiffies: Allow CLOCK_TICK_RATE to be undefined
Date: Mon, 23 Jul 2012 12:37:15 -0700 [thread overview]
Message-ID: <500DA7EB.1030608@linaro.org> (raw)
In-Reply-To: <20120719093704.GB27086@gmail.com>
On 07/19/2012 02:37 AM, Ingo Molnar wrote:
> * John Stultz <john.stultz@linaro.org> wrote:
>
>> From: Catalin Marinas <catalin.marinas@arm.com>
...
>> diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
>> index 265e2c3..a2134be 100644
>> --- a/include/linux/jiffies.h
>> +++ b/include/linux/jiffies.h
>> @@ -39,9 +39,6 @@
>> # error Invalid value of HZ.
>> #endif
>>
>> -/* LATCH is used in the interval timer and ftape setup. */
>> -#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
>> -
>> /* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can
>> * improve accuracy by shifting LSH bits, hence calculating:
>> * (NOM << LSH) / DEN
>> @@ -54,8 +51,15 @@
>> #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \
>> + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
>>
>> +#ifdef CLOCK_TICK_RATE
>> +/* LATCH is used in the interval timer and ftape setup. */
>> +#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
>> +
>> /* HZ is the requested value. ACTHZ is actual HZ ("<< 8" is for accuracy) */
>> #define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8))
>> +#else
>> +#define ACTHZ (HZ << 8)
>> +#endif
> The ACTHZ naming ugliness slipped past me. 'ACT' can mean so
> many things - please improve it to something more obvious, like
> 'REAL_HZ' or 'KERNEL_HZ'.
ACTHZ has been around for a while. ~2002 I think?
Is it ok if I do the rename in a following patch?
> Also, we tend to write such #if/#else/#endif patterns as:
>
> #if FOO
> # define BAR
> #else
> # define BAZ
> #endif
I'll fix this.
Thanks for the review
-john
next prev parent reply other threads:[~2012-07-23 19:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-19 1:19 [PATCH 0/2] Additional time changes for 3.6 John Stultz
2012-07-19 1:19 ` [PATCH 1/2] jiffies: Allow CLOCK_TICK_RATE to be undefined John Stultz
2012-07-19 9:37 ` Ingo Molnar
2012-07-23 19:37 ` John Stultz [this message]
2012-07-26 12:56 ` Ingo Molnar
2012-07-19 1:19 ` [PATCH 2/2] time: Cleanup offs_real/wall_to_mono and offs_boot/total_sleep_time updates John Stultz
2012-07-19 9:33 ` Ingo Molnar
2012-07-23 19:31 ` John Stultz
2012-07-26 12:57 ` Ingo Molnar
2012-07-19 12:37 ` Prarit Bhargava
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