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block: Add nr_bios to block_rq_remap tracepoint

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Adding the number of bios in a remapped request to 'block_rq_remap'
tracepoint.

Request remapper clones bios in a request to track the completion
status of each bio. So the number of bios can be useful information
for investigation.

Related discussions:
  http://www.redhat.com/archives/dm-devel/2013-August/msg00084.html
  http://www.redhat.com/archives/dm-devel/2013-September/msg00024.html

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jun'ichi Nomura 2013-09-21 13:57:47 -06:00 • committed by Jens Axboe
commit 75afb35299
2 changed files with 15 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

11
include/linux/blkdev.h
View file

@ -862,6 +862,17 @@ static inline unsigned int blk_rq_get_max_sectors(struct request *rq)
return blk_queue_get_max_sectors(q, rq->cmd_flags);
}
static inline unsigned int blk_rq_count_bios(struct request *rq)
{
unsigned int nr_bios = 0;
struct bio *bio;
__rq_for_each_bio(bio, rq)
nr_bios++;
return nr_bios;
}
/*
* Request issue related functions.
*/

6
include/trace/events/block.h
View file

@ -618,6 +618,7 @@ TRACE_EVENT(block_rq_remap,
__field( unsigned int, nr_sector )
__field( dev_t, old_dev )
__field( sector_t, old_sector )
__field( unsigned int, nr_bios )
__array( char, rwbs, RWBS_LEN)
),
@ -627,15 +628,16 @@ TRACE_EVENT(block_rq_remap,
__entry->nr_sector = blk_rq_sectors(rq);
__entry->old_dev = dev;
__entry->old_sector = from;
__entry->nr_bios = blk_rq_count_bios(rq);
blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq));
),
TP_printk("%d,%d %s %llu + %u <- (%d,%d) %llu",
TP_printk("%d,%d %s %llu + %u <- (%d,%d) %llu %u",
MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rwbs,
(unsigned long long)__entry->sector,
__entry->nr_sector,
MAJOR(__entry->old_dev), MINOR(__entry->old_dev),
(unsigned long long)__entry->old_sector)
(unsigned long long)__entry->old_sector, __entry->nr_bios)
);
#endif /* _TRACE_BLOCK_H */