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| author | Vladimir Davydov <vdavydov@parallels.com> | 2013-02-14 18:19:59 +0400 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2013-02-15 16:45:07 +0100 |
| commit | 5577022f4ed8973762450ebe7fe7ebfd953817db (patch) | |
| tree | c6c965101e32bf2b36155da0fc0ad94c696d4606 /block/blk-flush.c | |
| parent | 686855f5d833178e518d79e7912cdb3268a9fa69 (diff) | |
| download | lwn-5577022f4ed8973762450ebe7fe7ebfd953817db.tar.gz lwn-5577022f4ed8973762450ebe7fe7ebfd953817db.zip | |
block: account iowait time when waiting for completion of IO request
Using wait_for_completion() for waiting for a IO request to be executed
results in wrong iowait time accounting. For example, a system having
the only task doing write() and fdatasync() on a block device can be
reported being idle instead of iowaiting as it should because
blkdev_issue_flush() calls wait_for_completion() which in turn calls
schedule() that does not increment the iowait proc counter and thus does
not turn on iowait time accounting.
The patch makes block layer use wait_for_completion_io() instead of
wait_for_completion() where appropriate to account iowait time
correctly.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-flush.c')
| -rw-r--r-- | block/blk-flush.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c index 720ad607ff91..db8f1b507857 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -436,7 +436,7 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, bio_get(bio); submit_bio(WRITE_FLUSH, bio); - wait_for_completion(&wait); + wait_for_completion_io(&wait); /* * The driver must store the error location in ->bi_sector, if |