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SuSE 11.3 - man page for __round_jiffies (suse section 9)

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__ROUND_JIFFIES(9)			  Driver Basics 		       __ROUND_JIFFIES(9)

NAME
       __round_jiffies - function to round jiffies to a full second

SYNOPSIS
       unsigned long __round_jiffies(unsigned long j, int cpu);

ARGUMENTS
       j
	   the time in (absolute) jiffies that should be rounded

       cpu
	   the processor number on which the timeout will happen

DESCRIPTION
       __round_jiffies rounds an absolute time in the future (in jiffies) up or down to
       (approximately) full seconds. This is useful for timers for which the exact time they fire
       does not matter too much, as long as they fire approximately every X seconds.

       By rounding these timers to whole seconds, all such timers will fire at the same time,
       rather than at various times spread out. The goal of this is to have the CPU wake up less,
       which saves power.

       The exact rounding is skewed for each processor to avoid all processors firing at the
       exact same time, which could lead to lock contention or spurious cache line bouncing.

       The return value is the rounded version of the j parameter.

COPYRIGHT
Kernel Hackers Manual 2.6.		    July 2010			       __ROUND_JIFFIES(9)
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