PART_ROUND_STATS(9)                       Block Devices                       PART_ROUND_STATS(9)



NAME
       part_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
       second'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.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                       PART_ROUND_STATS(9)