Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <f1c3d717-339d-ba2b-9775-fc0e00f57ae3@huawei.com>
Date:   Fri, 12 Aug 2022 15:58:14 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.6.1
Subject: Re: [ata] 0568e61225: stress-ng.copy-file.ops_per_sec -15.0%
 regression
From:   John Garry <john.garry@huawei.com>
To:     Oliver Sang <oliver.sang@intel.com>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>
CC:     Christoph Hellwig <hch@lst.de>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Linux Memory Management List" <linux-mm@kvack.org>,
        <linux-ide@vger.kernel.org>, <lkp@lists.01.org>, <lkp@intel.com>,
        <ying.huang@intel.com>, <feng.tang@intel.com>,
        <zhengjun.xing@linux.intel.com>, <fengwei.yin@intel.com>
References: <YuzPMMnnY739Tnit@xsang-OptiPlex-9020>
 <1f498d4a-f93f-ceb4-b713-753196e5e08d@opensource.wdc.com>
 <3451fa5a-6229-073f-ae18-0c232cd48ed5@huawei.com>
 <e4106ffa-3842-45c0-9756-5226cfcfa17d@opensource.wdc.com>
 <YvXeuCAK780OuJPz@xsang-OptiPlex-9020>
 <2e9cf5a6-c043-5ccf-e363-097c6c941891@huawei.com>
In-Reply-To: <2e9cf5a6-c043-5ccf-e363-097c6c941891@huawei.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 12/08/2022 12:13, John Garry wrote:
>> On Tue, Aug 09, 2022 at 07:55:53AM -0700, Damien Le Moal wrote:
>>> On 2022/08/09 2:58, John Garry wrote:
>>>> On 08/08/2022 15:52, Damien Le Moal wrote:
>>>>> On 2022/08/05 1:05, kernel test robot wrote:
>>>>>>
>>>>>>
>>>>>> Greeting,
>>>>>>
>>>>>> FYI, we noticed a -15.0% regression of 
>>>>>> stress-ng.copy-file.ops_per_sec due to commit:
>>>>>>
>>>>>>
>>>>>> commit: 0568e6122574dcc1aded2979cd0245038efe22b6 ("ata: 
>>>>>> libata-scsi: cap ata_device->max_sectors according to 
>>>>>> shost->max_sectors")
>>>>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git 
>>>>>> master
>>>>>>
>>>>>> in testcase: stress-ng
>>>>>> on test machine: 96 threads 2 sockets Ice Lake with 256G memory
>>>>>> with following parameters:
>>>>>>
>>>>>>     nr_threads: 10%
>>>>>>     disk: 1HDD
>>>>>>     testtime: 60s
>>>>>>     fs: f2fs
>>>>>>     class: filesystem
>>>>>>     test: copy-file
>>>>>>     cpufreq_governor: performance
>>>>>>     ucode: 0xb000280
>>>>>
>>>>> Without knowing what the device adapter is, hard to say where the 
>>>>> problem is. I
>>>>> suspect that with the patch applied, we may be ending up with a 
>>>>> small default
>>>>> max_sectors value, causing overhead due to more commands than 
>>>>> necessary.
>>>>>
>>>>> Will check what I see with my test rig.
>>>>
>>>> As far as I can see, this patch should not make a difference unless the
>>>> ATA shost driver is setting the max_sectors value unnecessarily low.
>>>
>>> That is my hunch too, hence my question about which host driver is 
>>> being used
>>> for this test... That is not apparent from the problem report.
>>
>> we noticed the commit is already in mainline now, and in our tests, 
>> there is
>> still similar regression and also on other platforms.
>> could you guide us how to check "which host driver is being used for this
>> test"? hope to supply some useful information.
>>
> 
> For me, a complete kernel log may help.

and since only 1HDD, the output of the following would be helpful:

/sys/block/sda/queue/max_sectors_kb
/sys/block/sda/queue/max_hw_sectors_kb

And for 5.19, if possible.

Thanks!

> 
>>>
>>>>