Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6

Jens Axboe
2019-09-25T19:36:36Z

On 9/25/19 9:30 PM, Alan Stern wrote:
> On Fri, 20 Sep 2019, Andrea Vai wrote:
>
>> Il giorno gio, 19/09/2019 alle 14.14 +0000, Damien Le Moal ha scritto:
>>> On 2019/09/19 16:01, Alan Stern wrote:
>>> [...]
>>>> No doubt Andrea will be happy to test your fix when it's ready.
>>
>> Yes, of course.
>>
>>>
>>> Hannes posted an RFC series:
>>>
>>> https://www.spinics.net/lists/linux-scsi/msg133848.html
>>>
>>> Andrea can try it.
>>
>> Ok, but I would need some instructions please, because I am not able
>> to understand how to "try it". Sorry for that.
>
> I have attached the two patches to this email. You should start with a
> recent kernel source tree and apply the patches by doing:
>
> git apply patch1 patch2
>
> or something similar. Then build a kernel from the new source code and
> test it.
>
> Ultimately, if nobody can find a way to restore the sequential I/O
> behavior we had prior to commit f664a3cc17b7, that commit may have to
> be reverted.

Don't use patch1, it's buggy. patch2 should be enough to test the theory.

--
Jens Axboe