From 5577022f4ed8973762450ebe7fe7ebfd953817db Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Thu, 14 Feb 2013 18:19:59 +0400 Subject: 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 Signed-off-by: Jens Axboe --- block/blk-flush.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block/blk-flush.c') diff --git a/block/blk-flush.c b/block/blk-flush.c index 720ad607ff9..db8f1b50785 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 -- cgit v1.2.3