diff options
| author |   Mikulas Patocka <mpatocka@redhat.com> | 2018-12-06 11:41:19 -0500 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2018-12-10 08:30:37 -0700 |
| commit | 5b18b5a737600fd20ba2045f320d5926ebbf341a (patch) | |
| tree | fe35e150bf36785dfe3ed8c845e3b043e56f9f90 /include/linux/genhd.h | |
| parent | block: stop passing 'cpu' to all percpu stats methods (diff) | |
| download | linux-dev-5b18b5a737600fd20ba2045f320d5926ebbf341a.tar.xz linux-dev-5b18b5a737600fd20ba2045f320d5926ebbf341a.zip | |
block: delete part_round_stats and switch to less precise counting
We want to convert to per-cpu in_flight counters.
The function part_round_stats needs the in_flight counter every jiffy, it
would be too costly to sum all the percpu variables every jiffy, so it
must be deleted. part_round_stats is used to calculate two counters -
time_in_queue and io_ticks.
time_in_queue can be calculated without part_round_stats, by adding the
duration of the I/O when the I/O ends (the value is almost as exact as the
previously calculated value, except that time for in-progress I/Os is not
counted).
io_ticks can be approximated by increasing the value when I/O is started
or ended and the jiffies value has changed. If the I/Os take less than a
jiffy, the value is as exact as the previously calculated value. If the
I/Os take more than a jiffy, io_ticks can drift behind the previously
calculated value.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/genhd.h')
| -rw-r--r-- | include/linux/genhd.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 1677cd2a4c4e..838c2a7a40c5 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -398,8 +398,7 @@ static inline void free_part_info(struct hd_struct *part) kfree(part->info); } -/* block/blk-core.c */ -extern void part_round_stats(struct request_queue *q, struct hd_struct *part); +void update_io_ticks(struct hd_struct *part, unsigned long now); /* block/genhd.c */ extern void device_add_disk(struct device *parent, struct gendisk *disk, |