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Message-ID: <b2f78d54-005c-d719-9a98-aeb8a8fe991b@huawei.com>
Date:   Thu, 10 Feb 2022 11:04:51 +0800
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Subject: Re: [PATCH -next] block: update io_ticks when io hang
From:   "zhangwensheng (E)" <zhangwensheng5@huawei.com>
To:     <axboe@kernel.dk>
CC:     <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20220125091938.1799001-1-zhangwensheng5@huawei.com>
 <45c2ae11-c44e-f27d-f029-66efe96b0804@huawei.com>
 <6e7fe188-a258-8d10-2f86-027c6b6f434c@huawei.com>
In-Reply-To: <6e7fe188-a258-8d10-2f86-027c6b6f434c@huawei.com>
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friendly ping...

在 2022/2/8 10:12, zhangwensheng (E) 写道:
> friendly ping...
>
> 在 2022/1/28 14:22, zhangwensheng (E) 写道:
>> friendly ping...
>>
>> 在 2022/1/25 17:19, Zhang Wensheng 写道:
>>> When the inflight IOs are slow and no new IOs are issued, we expect
>>> iostat could manifest the IO hang problem. However after
>>> commit 5b18b5a73760 ("block: delete part_round_stats and switch to less
>>> precise counting"), io_tick and time_in_queue will not be updated until
>>> the end of IO, and the avgqu-sz and %util columns of iostat will be 
>>> zero.
>>>
>>> Because it has using stat.nsecs accumulation to express time_in_queue
>>> which is not suitable to change, and may %util will express the status
>>> better when io hang occur. To fix io_ticks, we use update_io_ticks and
>>> inflight to update io_ticks when diskstats_show and part_stat_show
>>> been called.
>>>
>>> Fixes: 5b18b5a73760 ("block: delete part_round_stats and switch to 
>>> less precise counting")
>>> Signed-off-by: Zhang Wensheng <zhangwensheng5@huawei.com>
>>> ---
>>>   block/genhd.c | 8 ++++++--
>>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/block/genhd.c b/block/genhd.c
>>> index 626c8406f21a..df0656ffb4ad 100644
>>> --- a/block/genhd.c
>>> +++ b/block/genhd.c
>>> @@ -913,12 +913,14 @@ ssize_t part_stat_show(struct device *dev,
>>>       struct disk_stats stat;
>>>       unsigned int inflight;
>>>   -    part_stat_read_all(bdev, &stat);
>>>       if (queue_is_mq(q))
>>>           inflight = blk_mq_in_flight(q, bdev);
>>>       else
>>>           inflight = part_in_flight(bdev);
>>>   +    if (inflight)
>>> +        update_io_ticks(bdev, jiffies, true);
>>> +    part_stat_read_all(bdev, &stat);
>>>       return sprintf(buf,
>>>           "%8lu %8lu %8llu %8u "
>>>           "%8lu %8lu %8llu %8u "
>>> @@ -1174,12 +1176,14 @@ static int diskstats_show(struct seq_file 
>>> *seqf, void *v)
>>>       xa_for_each(&gp->part_tbl, idx, hd) {
>>>           if (bdev_is_partition(hd) && !bdev_nr_sectors(hd))
>>>               continue;
>>> -        part_stat_read_all(hd, &stat);
>>>           if (queue_is_mq(gp->queue))
>>>               inflight = blk_mq_in_flight(gp->queue, hd);
>>>           else
>>>               inflight = part_in_flight(hd);
>>>   +        if (inflight)
>>> +            update_io_ticks(hd, jiffies, true);
>>> +        part_stat_read_all(hd, &stat);
>>>           seq_printf(seqf, "%4d %7d %pg "
>>>                  "%lu %lu %lu %u "
>>>                  "%lu %lu %lu %u "