Messages in this thread Patch in this message | | | Date | Wed, 12 May 2004 22:50:28 +0200 | From | Ingo Molnar <> | Subject | Re: MSEC_TO_JIFFIES is messed up... |
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* Ingo Molnar <mingo@elte.hu> wrote:
> new patch attached - this adopts the overflow-safe variant from > sctp.h, removes it from sctp.h and moves it into a generic include > file and also does the HZ=1000 simplification.
yet another patch - this time it's: complete, covers irda, accelerates HZ=100, unifies the slightly differing namespaces and compiles/boots as well.
Ingo --- linux/include/linux/time.h.orig +++ linux/include/linux/time.h @@ -177,6 +177,24 @@ struct timezone { (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) #endif + +/* + * Convert jiffies to milliseconds and back. + * + * Avoid unnecessary multiplications/divisions in the + * two most common HZ cases: + */ +#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) / 10) +#else +# define JIFFIES_TO_MSECS(x) ((x) * 1000 / HZ) +# define MSECS_TO_JIFFIES(x) ((x) * HZ / 1000) +#endif + /* * The TICK_NSEC - 1 rounds up the value to the next resolution. Note * that a remainder subtract here would not do the right thing as the --- linux/include/net/irda/irda.h.orig +++ linux/include/net/irda/irda.h @@ -83,8 +83,6 @@ if(!(expr)) do { \ #define MESSAGE(args...) printk(KERN_INFO args) #define ERROR(args...) printk(KERN_ERR args) -#define MSECS_TO_JIFFIES(ms) (((ms)*HZ+999)/1000) - /* * Magic numbers used by Linux-IrDA. Random numbers which must be unique to * give the best protection --- linux/include/net/sctp/sctp.h.orig +++ linux/include/net/sctp/sctp.h @@ -116,11 +116,6 @@ #define SCTP_STATIC static #endif -#define MSECS_TO_JIFFIES(msec) \ - (((msec / 1000) * HZ) + ((msec % 1000) * HZ) / 1000) -#define JIFFIES_TO_MSECS(jiff) \ - (((jiff / HZ) * 1000) + ((jiff % HZ) * 1000) / HZ) - /* * Function declarations. */ --- linux/include/asm-i386/param.h.orig +++ linux/include/asm-i386/param.h @@ -5,8 +5,6 @@ # define HZ 1000 /* Internal kernel timer frequency */ # define USER_HZ 100 /* .. some user interfaces are in "ticks" */ # define CLOCKS_PER_SEC (USER_HZ) /* like times() */ -# define JIFFIES_TO_MSEC(x) (x) -# define MSEC_TO_JIFFIES(x) (x) #endif #ifndef HZ --- linux/kernel/sched.c.orig +++ linux/kernel/sched.c @@ -75,13 +75,6 @@ #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ)) #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ)) -#ifndef JIFFIES_TO_MSEC -# define JIFFIES_TO_MSEC(x) ((x) * 1000 / HZ) -#endif -#ifndef MSEC_TO_JIFFIES -# define MSEC_TO_JIFFIES(x) ((x) * HZ / 1000) -#endif - /* * These are the 'tuning knobs' of the scheduler: * @@ -1880,7 +1873,7 @@ static void rebalance_tick(int this_cpu, interval *= sd->busy_factor; /* scale ms to jiffies */ - interval = MSEC_TO_JIFFIES(interval); + interval = MSECS_TO_JIFFIES(interval); if (unlikely(!interval)) interval = 1;
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