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SubjectRe: [PATCH 1/2] jiffies: Allow CLOCK_TICK_RATE to be undefined

* John Stultz <john.stultz@linaro.org> wrote:

> 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?

Time flies!

> Is it ok if I do the rename in a following patch?

Sure.

> >Also, we tend to write such #if/#else/#endif patterns as:
> >
> >#if FOO
> ># define BAR
> >#else
> ># define BAZ
> >#endif
> I'll fix this.

Thanks!

Ingo


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