From: Yu Kuai <yukuai1@huaweicloud.com>
To: lkp@lists.01.org
Subject: Re: [blk] 8c5035dfbb: fio.read_iops -10.6% regression
Date: Sun, 09 Oct 2022 17:32:34 +0800 [thread overview]
Message-ID: <e81ea0fe-dcd2-1e5d-9b78-3c79751b3097@huaweicloud.com> (raw)
In-Reply-To: <Y0KJmODYOh83OtGa@T590>
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Hi,
在 2022/10/09 16:43, Ming Lei 写道:
> On Sat, Oct 08, 2022 at 04:00:10PM +0800, Yu Kuai wrote:
>> Hi,
>>
>> 在 2022/10/08 10:50, kernel test robot 写道:
>>> Greeting,
>>>
>>> FYI, we noticed a -10.6% regression of fio.read_iops due to commit:
>>
>> I don't know how this is working but I'm *sure* this commit won't affect
>
> Looks it is wrong to move
>
> wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
>
> before rq_qos_add() in wbt_init().
>
> Without adding wbt rq_qos, wbt_set_write_cache is just a nop.
Yes, I got it now, I'm being foolish here.
I missed that "rwb->wc" is got by rq_qos in wbt_set_write_cache(), which
is NULL before rq_qos_add(). By the way, it's interesting that how read
performance is affected, I still don't know why yet...
Thanks,
Kuai
>
>
> thanks,
> Ming
>
> .
>
next prev parent reply other threads:[~2022-10-09 9:32 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-08 2:50 [blk] 8c5035dfbb: fio.read_iops -10.6% regression kernel test robot
2022-10-08 8:00 ` Yu Kuai
2022-10-09 5:47 ` Yin Fengwei
2022-10-09 6:14 ` Yu Kuai
2022-10-09 8:43 ` Ming Lei
2022-10-09 9:32 ` Yu Kuai [this message]
2022-10-13 7:42 ` Feng Tang
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