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Subject: Re: raid0 vs. mkfs
To: Avi Kivity <avi@scylladb.com>, Shaohua Li <shli@kernel.org>
Cc: NeilBrown <neilb@suse.com>, linux-raid@vger.kernel.org,
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From: Coly Li <colyli@suse.de>
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Date: Thu, 29 Jun 2017 23:31:38 +0800
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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.

Coly