Commit d80c228d authored by Chunguang Xu's avatar Chunguang Xu Committed by Jens Axboe
Browse files

block: fix the problem of io_ticks becoming smaller 



On the IO submission path, blk_account_io_start() may interrupt
the system interruption. When the interruption returns, the value
of part->stamp may have been updated by other cores, so the time
value collected before the interruption may be less than part->
stamp. So when this happens, we should do nothing to make io_ticks
more accurate? For kernels less than 5.0, this may cause io_ticks
to become smaller, which in turn may cause abnormal ioutil values.

Signed-off-by: default avatarChunguang Xu <brookxu@tencent.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/1625521646-1069-1-git-send-email-brookxu.cn@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c6af8db9

block/blk-core.c

+1 −1
Original line number Diff line number Diff line
@@ -1241,7 +1241,7 @@ static void update_io_ticks(struct block_device *part, unsigned long now, 
	unsigned long stamp;

again:

	stamp = READ_ONCE(part->bd_stamp);

	if (unlikely(stamp != now)) {

	if (unlikely(time_after(now, stamp))) {

		if (likely(cmpxchg(&part->bd_stamp, stamp, now) == stamp))

			__part_stat_add(part, io_ticks, end ? now - stamp : 1);

	}