Re: raid0 vs. mkfs

[Avi Kivity <avi@scylladb.com>]

On 06/29/2017 06:31 PM, Coly Li wrote:
> On 2017/6/29 下午11:15, Avi Kivity wrote:
>>
>> On 12/08/2016 06:44 PM, Coly Li wrote:
>>> On 2016/12/8 上午12:59, Shaohua Li wrote:
>>>> On Wed, Dec 07, 2016 at 07:50:33PM +0800, Coly Li wrote:
>>> [snip]
>>>> Thanks for doing this, Coly! For raid0, this totally makes sense. The
>>>> raid0
>>>> zones make things a little complicated though. I just had a brief
>>>> look of your
>>>> proposed patch, which looks really complicated. I'd suggest something
>>>> like
>>>> this:
>>>> 1. split the bio according to zone boundary.
>>>> 2. handle the splitted bio. since the bio is within zone range,
>>>> calculating
>>>> the start and end sector for each rdev should be easy.
>>>>
>>> Hi Shaohua,
>>>
>>> Thanks for your suggestion! I try to modify the code by your suggestion,
>>> it is even more hard to make the code that way ...
>>>
>>> Because even split bios for each zone, all the corner cases still exist
>>> and should be taken care in every zoon. The code will be more
>>> complicated.
>>>
>> Hi Coly,
>>
>> Did you manage to complete this patch? We are seeing its effect, not
>> only with mkfs, but also with fstrim(8).
> Hi Avi,
>
> Shaohua makes another much better patch, which is merged into mainline
> kernel in v4.12-rc2.
>
> The commit is '29efc390b946 ("md/md0: optimize raid0 discard handling")'.
>
> Hope this is informative.
>

Thanks a lot, that's great news.