Commit dc10885d authored by Linus Torvalds's avatar Linus Torvalds

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
......@@ -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);
}
......
......@@ -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 */
......@@ -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__ */
......
......@@ -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);
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