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Commit dc10885d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'core/iter-div' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 

* 'core/iter-div' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  always_inline timespec_add_ns
  add an inlined version of iter_div_u64_rem
  common implementation of iterative div/mod
parents 631025b4 9412e286

arch/x86/xen/time.c

+3 −10
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/clocksource.h>

#include <linux/clockchips.h>

#include <linux/kernel_stat.h>

#include <linux/math64.h>



#include <asm/xen/hypervisor.h>

#include <asm/xen/hypercall.h>
@@ -150,11 +151,7 @@ static void do_stolen_accounting(void) 
	if (stolen < 0)

		stolen = 0;



	ticks = 0;

	while (stolen >= NS_PER_TICK) {

		ticks++;

		stolen -= NS_PER_TICK;

	}

	ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen);

	__get_cpu_var(residual_stolen) = stolen;

	account_steal_time(NULL, ticks);
@@ -166,11 +163,7 @@ static void do_stolen_accounting(void) 
	if (blocked < 0)

		blocked = 0;



	ticks = 0;

	while (blocked >= NS_PER_TICK) {

		ticks++;

		blocked -= NS_PER_TICK;

	}

	ticks = iter_div_u64_rem(blocked, NS_PER_TICK, &blocked);

	__get_cpu_var(residual_blocked) = blocked;

	account_steal_time(idle_task(smp_processor_id()), ticks);

}

include/linux/math64.h

+21 −0
Original line number Diff line number Diff line
@@ -81,4 +81,25 @@ static inline s64 div_s64(s64 dividend, s32 divisor) 
}

#endif



u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);



static __always_inline u32

__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)

{

	u32 ret = 0;



	while (dividend >= divisor) {

		/* The following asm() prevents the compiler from

		   optimising this loop into a modulo operation.  */

		asm("" : "+rm"(dividend));



		dividend -= divisor;

		ret++;

	}



	*remainder = dividend;



	return ret;

}



#endif /* _LINUX_MATH64_H */

include/linux/time.h

+6 −10
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#ifdef __KERNEL__

# include <linux/cache.h>

# include <linux/seqlock.h>

# include <linux/math64.h>

#endif



#ifndef _STRUCT_TIMESPEC
@@ -169,18 +170,13 @@ extern struct timeval ns_to_timeval(const s64 nsec); 
 * timespec_add_ns - Adds nanoseconds to a timespec

 * @a:		pointer to timespec to be incremented

 * @ns:		unsigned nanoseconds value to be added

 *

 * This must always be inlined because its used from the x86-64 vdso,

 * which cannot call other kernel functions.

 */

static inline void timespec_add_ns(struct timespec *a, u64 ns)

static __always_inline void timespec_add_ns(struct timespec *a, u64 ns)

{

	ns += a->tv_nsec;

	while(unlikely(ns >= NSEC_PER_SEC)) {

		/* The following asm() prevents the compiler from

		 * optimising this loop into a modulo operation.  */

		asm("" : "+r"(ns));



		ns -= NSEC_PER_SEC;

		a->tv_sec++;

	}

	a->tv_sec += __iter_div_u64_rem(a->tv_nsec + ns, NSEC_PER_SEC, &ns);

	a->tv_nsec = ns;

}

#endif /* __KERNEL__ */

lib/div64.c

+10 −0
Original line number Diff line number Diff line
@@ -98,3 +98,13 @@ EXPORT_SYMBOL(div64_u64); 
#endif



#endif /* BITS_PER_LONG == 32 */



/*

 * Iterative div/mod for use when dividend is not expected to be much

 * bigger than divisor.

 */

u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)

{

	return __iter_div_u64_rem(dividend, divisor, remainder);

}

EXPORT_SYMBOL(iter_div_u64_rem);