Messages in this thread Patch in this message | | | Date | Thu, 13 May 2004 12:11:41 -0700 | From | Andrew Morton <> | Subject | Re: MSEC_TO_JIFFIES is messed up... |
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Paul Wagland <paul@wagland.net> wrote: > > > -#if HZ == 1000 > > -# define JIFFIES_TO_MSECS(x) (x) > > -# define MSECS_TO_JIFFIES(x) (x) > > -#elif HZ == 100 > > -# define JIFFIES_TO_MSECS(x) ((x) * 10) > > -# define MSECS_TO_JIFFIES(x) (((x) + 9) / 10) > > +#if HZ <= 1000 && !(1000 % HZ) > > +# define JIFFIES_TO_MSECS(j) ((1000/HZ)*(j)) > > +# define MSECS_TO_JIFFIES(m) (((m) + (1000/HZ) - 1)/(1000/HZ)) > > +#elif HZ > 1000 && !(HZ % 1000) > > +# define JIFFIES_TO_MSECS(j) (((j) + (HZ/1000) - 1)/(HZ/1000)) > > +# define MSECS_TO_JIFFIES(m) ((m)*(HZ/1000)) > > #else > > # define JIFFIES_TO_MSECS(x) (((x) * 1000) / HZ) > > # define MSECS_TO_JIFFIES(x) (((x) * HZ + 999) / 1000) > > Also, can we keep the same parameter name across all of the macros?
Fair enough.
--- 25/include/linux/time.h~MSEC_TO_JIFFIES-fixups-tidy 2004-05-13 12:09:27.463273344 -0700 +++ 25-akpm/include/linux/time.h 2004-05-13 12:09:41.300169816 -0700 @@ -191,8 +191,8 @@ struct timezone { # define JIFFIES_TO_MSECS(j) (((j) + (HZ/1000) - 1)/(HZ/1000)) # define MSECS_TO_JIFFIES(m) ((m)*(HZ/1000)) #else -# define JIFFIES_TO_MSECS(x) (((x) * 1000) / HZ) -# define MSECS_TO_JIFFIES(x) (((x) * HZ + 999) / 1000) +# define JIFFIES_TO_MSECS(j) (((j) * 1000) / HZ) +# define MSECS_TO_JIFFIES(m) (((m) * HZ + 999) / 1000) #endif /* > This changes behaviour when HZ==(z)000 > > JIFFIES_TO_MSECS goes from > ((x) * 1000) / (z)000 to (((x) + (z) - 1)/(z)) > > i.e. for x=1, z=2 this goes from ((1)*1000)/2000)=0 to (((1)+(2)-1)/2)=1
hm, so you're saying that we now round 0.5 up to 1 rather than down to zero?
> However, MSECS_TO_JIFFIES remains the same going from > (((x) * (z)000 + 999) / 1000) to ((x)*(z)) > > I.e. they basically reduce down to the same thing (modulo overflows) > > All of the other permuations look correct to me... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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