1PART_ROUND_STATS(9)              Block Devices             PART_ROUND_STATS(9)
2
3
4

NAME

6       part_round_stats - Round off the performance stats on a struct
7       disk_stats.
8

SYNOPSIS

10       void part_round_stats(int cpu, struct hd_struct * part);
11

ARGUMENTS

13       cpu
14           cpu number for stats access
15
16       part
17           target partition
18

DESCRIPTION

20       The average IO queue length and utilisation statistics are maintained
21       by observing the current state of the queue length and the amount of
22       time it has been in this state for.
23
24       Normally, that accounting is done on IO completion, but that can result
25       in more than a second´s worth of IO being accounted for within any one
26       second, leading to >100% utilisation. To deal with that, we call this
27       function to do a round-off before returning the results when reading
28       /proc/diskstats. This accounts immediately for all queue usage up to
29       the current jiffies and restarts the counters again.
30

32Kernel Hackers Manual 2.6.         June 2019               PART_ROUND_STATS(9)
Impressum