| From b6d057019fdbbafa08403d32a2600e71edf16262 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 6 Jul 2021 05:47:26 +0800 |
| Subject: block: fix the problem of io_ticks becoming smaller |
| |
| From: Chunguang Xu <brookxu@tencent.com> |
| |
| [ Upstream commit d80c228d44640f0b47b57a2ca4afa26ef87e16b0 ] |
| |
| 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: Chunguang Xu <brookxu@tencent.com> |
| Reviewed-by: Christoph Hellwig <hch@lst.de> |
| Link: https://lore.kernel.org/r/1625521646-1069-1-git-send-email-brookxu.cn@gmail.com |
| Signed-off-by: Jens Axboe <axboe@kernel.dk> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| block/blk-core.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/block/blk-core.c b/block/blk-core.c |
| index fc60ff208497..e34dfa13b7bc 100644 |
| --- a/block/blk-core.c |
| +++ b/block/blk-core.c |
| @@ -1255,7 +1255,7 @@ 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); |
| } |
| -- |
| 2.30.2 |
| |