Messages in this thread | | | Date | Mon, 23 Jul 2012 12:37:15 -0700 | From | John Stultz <> | Subject | Re: [PATCH 1/2] jiffies: Allow CLOCK_TICK_RATE to be undefined |
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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
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