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

[John Stultz]

On 07/19/2012 02:37 AM, Ingo Molnar wrote:
> * John Stultz <john.stultz@xxxxxxxxxx> wrote:
>
> > From: Catalin Marinas <catalin.marinas@xxxxxxx>
...
> > 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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