linux-kernel - Re: [PATCH v5] erofs: add per-cpu threads for decompression as an option

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Date:   Tue, 28 Feb 2023 13:58:56 +0800
From:   Gao Xiang <hsiangkao@...ux.alibaba.com>
To:     Sandeep Dhavale <dhavale@...gle.com>
Cc:     linux-erofs@...ts.ozlabs.org, LKML <linux-kernel@...r.kernel.org>,
        Nathan Huckleberry <nhuck@...gle.com>,
        Yue Hu <huyue2@...lpad.com>, kernel-team@...roid.com
Subject: Re: [PATCH v5] erofs: add per-cpu threads for decompression as an
 option



On 2023/2/28 13:51, Sandeep Dhavale wrote:
> On Mon, Feb 27, 2023 at 9:01 PM Gao Xiang <hsiangkao@...ux.alibaba.com> wrote:
>>
>> Hi Sandeep,
>>
>> On 2023/2/28 12:47, Sandeep Dhavale via Linux-erofs wrote:
>>> Hi all,
>>> I completed the tests and the results are consistent with
>>> our previous observation. We can see that removing WQ_UNBOUND
>>> helps but the scheduling latency by using high priority per cpu
>>> kthreads is even lower. Below is the table.
>>>
>>> |---------------------+-------+-------+------+-------|
>>> | Table               | avg   | med   | min  | max   |
>>> |---------------------+-------+-------+------+-------|
>>> | Default erofs       | 19323 | 19758 | 3986 | 35051 |
>>> |---------------------+-------+-------+------+-------|
>>> | !WQ_UNBOUND         | 11202 | 10798 | 3493 | 19822 |
>>> |---------------------+-------+-------+------+-------|
>>> | hipri pcpu kthreads | 7182  | 7017  | 2463 | 12300 |
>>> |---------------------+-------+-------+------+-------|
>>
>> May I ask did it test with different setup since the test results
>> in the original commit message are:
>>
> Hi Gao,
> Yes I did the test on the different (older) hardware than my original testing
> (but the same one Nathan had used) to remove that as a variable.

Ok, good to know that.

> 
> Thanks,
> Sandeep.
> 
>> +-------------------------+-----------+----------------+---------+
>> |                         | workqueue | kthread_worker |  diff   |
>> +-------------------------+-----------+----------------+---------+
>> | Average (us)            |     15253 |           2914 | -80.89% |
>> | Median (us)             |     14001 |           2912 | -79.20% |
>> | Minimum (us)            |      3117 |           1027 | -67.05% |
>> | Maximum (us)            |     30170 |           3805 | -87.39% |
>> | Standard deviation (us) |      7166 |            359 |         |
>> +-------------------------+-----------+----------------+---------+
>>
>> Otherwise it looks good to me for now, hopefully helpful to Android
>> users.
>>
>> Thanks,
>> Gao Xiang
>>
>>>
>>>
>>> Thanks,
>>> Sandeep.