__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)
