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SubjectRe: [PATCH v2 2/2] md: don't account sync_io if iostats of the disk is disabled
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在 2023/12/15 17:08, Song Liu 写道:
> On Thu, Dec 14, 2023 at 5:41 PM <linan666@huaweicloud.com> wrote:
>>
>> From: Li Nan <linan122@huawei.com>
>>
>> If iostats is disabled, disk_stats will not be updated and
>> part_stat_read_accum() only returns a constant value. In this case,
>> continuing to count sync_io and to check is_mddev_idle() is no longer
>> meaningful.
>>
>> Signed-off-by: Li Nan <linan122@huawei.com>
>> ---
>> drivers/md/md.h | 3 ++-
>> drivers/md/md.c | 4 ++++
>> 2 files changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/md/md.h b/drivers/md/md.h
>> index 1a4f976951c1..75f5c5d04e71 100644
>> --- a/drivers/md/md.h
>> +++ b/drivers/md/md.h
>> @@ -589,7 +589,8 @@ static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sect
>>
>> static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
>> {
>> - md_sync_acct(bio->bi_bdev, nr_sectors);
>> + if (blk_queue_io_stat(bio->bi_bdev->bd_disk->queue))
>> + md_sync_acct(bio->bi_bdev, nr_sectors);
>
> Do we need the same check for md_sync_acct()?
>
>> }
>>
>> struct md_personality
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 1d71b2a9af03..18bbceb0ffd6 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -8502,6 +8502,10 @@ static int is_mddev_idle(struct mddev *mddev, int init)
>> rcu_read_lock();
>> rdev_for_each_rcu(rdev, mddev) {
>> struct gendisk *disk = rdev->bdev->bd_disk;
>> +
>> + if (blk_queue_io_stat(mddev->queue))
>> + continue;
>
> This looks weird. Do you mean
>
> if (!blk_queue_io_stat(disk->queue))
>
> Note that I changed two things here: 1) add "!"; 2) check disk, not mddev.
>
> Did I miss something?
>
> Thanks,
> Song
>

Yeah... It's my bad. I will fix it in v3.

>> +
>> curr_events =
>> (long long)part_stat_read_accum(disk->part0, sectors) -
>> atomic64_read(&disk->sync_io);
>> --
>> 2.39.2
>>
>
> .

--
Thanks,
Nan


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