Re: MSEC_TO_JIFFIES is messed up...

From: Ingo Molnar
Date: Wed May 12 2004 - 15:49:06 EST



* Ingo Molnar <mingo@xxxxxxx> wrote:

> the attached patch (against BK-curr) cleans this up and makes the
> defines generic and arch-independent.

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.

Ingo
--- linux/include/linux/time.h.orig
+++ linux/include/linux/time.h
@@ -177,6 +177,17 @@ struct timezone {
(SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)

#endif
+
+#if HZ == 1000
+# define JIFFIES_TO_MSEC(x) (x)
+# define MSEC_TO_JIFFIES(x) (x)
+#else
+#define MSECS_TO_JIFFIES(msec) \
+ (((msec / 1000) * HZ) + ((msec % 1000) * HZ) / 1000)
+#define JIFFIES_TO_MSECS(jiff) \
+ (((jiff / HZ) * 1000) + ((jiff % HZ) * 1000) / HZ)
+#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/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:
*