PART_ROUND_STATS(9) Block Devices PART_ROUND_STATS(9)NAMEpart_round_stats - Round off the performance stats on a struct
disk_stats.
SYNOPSIS
void part_round_stats(int cpu, struct hd_struct * part);
ARGUMENTS
cpu
cpu number for stats access
part
target partition
DESCRIPTION
The average IO queue length and utilisation statistics are maintained
by observing the current state of the queue length and the amount of
time it has been in this state for.
Normally, that accounting is done on IO completion, but that can result
in more than a secondĀ“s worth of IO being accounted for within any one
second, leading to >100% utilisation. To deal with that, we call this
function to do a round-off before returning the results when reading
/proc/diskstats. This accounts immediately for all queue usage up to
the current jiffies and restarts the counters again.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 PART_ROUND_STATS(9)