Messages in this thread | | | Date | Mon, 29 Mar 2004 11:57:54 -0800 (PST) | From | Sridhar Samudrala <> | Subject | Re: [PATCH] Consolidate multiple implementations of jiffies-msecs conversions. |
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On Fri, 26 Mar 2004, Jeff Garzik wrote:
> Sridhar Samudrala wrote: > > On Fri, 26 Mar 2004, Edgar Toernig wrote: > > > > > >>Sridhar Samudrala wrote: > >> > >>>The following patch to 2.6.5-rc2 consolidates 6 different implementations > >>>of msecs to jiffies and 3 different implementation of jiffies to msecs. > >>>All of them now use the generic msecs_to_jiffies() and jiffies_to_msecs() > >>>that are added to include/linux/time.h > >>>[...] > >>>-#define MSECS(ms) (((ms)*HZ/1000)+1) > >>>-return (((ms)*HZ+999)/1000); > >>>+return (msecs / 1000) * HZ + (msecs % 1000) * HZ / 1000; > >> > >>Did you check that all users of the new version will work correctly > >>with your rounding? Explicit round-up of delays is often required, > >>especially when talking to hardware... > > > > > > I don't see any issues with the 2.6 default HZ value of 1000 as they become > > no-ops and there is no need for any rounding. > > I guess you are referring to cases when HZ < 1000(ex: 100) and msecs is > > less than 10. In those cases, the new version returns 0, whereas some of the > > older versions return 1. > > We'll definitely want to return 1 rather than zero, for the uses in my > drivers, at least...
I have modified msecs_to_jiffies() to do the proper rounding when HZ=100. Do these work better?
static inline unsigned long msecs_to_jiffies(unsigned long msecs) { #if 1000 % HZ == 0 return (msecs + ((1000 / HZ) - 1)) / (1000 / HZ); #elif HZ % 1000 == 0 return msecs * (HZ / 1000); #else return (msecs / 1000) * HZ + (msecs % 1000) * HZ / 1000; #endif }
static inline unsigned long jiffies_to_msecs(unsigned long jiffs) { #if 1000 % HZ == 0 return jiffs * (1000 / HZ); #elif HZ % 1000 == 0 return jiffs / (HZ / 1000); #else return (jiffs / HZ) * 1000 + (jiffs % HZ) * 1000 / HZ; #endif }
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