Re: [PATCH v2 2/2] lightnvm: add non-continuous lun target creation support

Wenwei Tao
2016-01-28T10:19:54Z

OK, I see. Will include these changes in next version.

2016-01-28 17:09 GMT+08:00 Matias Bjørling <mb@lightnvm.io>:
> On 01/28/2016 09:50 AM, Wenwei Tao wrote:
>> 2016-01-27 17:44 GMT+08:00 Matias Bjørling <mb@lightnvm.io>:
>>> On 01/26/2016 01:33 PM, Wenwei Tao wrote:
>>>> When create a target, we specify the begin lunid and
>>>> the end lunid, and get the corresponding continuous
>>>> luns from media manager, if one of the luns is not free,
>>>> we failed to create the target, even if the device's
>>>> total free luns are enough.
>>>>
>>>> So add non-continuous lun target creation support,
>>>> thus we can improve the backend device's space utilization.
>>>> Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com>
>>>> ---
>>>> Changes since v1:
>>>> -use NVM_FIXED instead NVM_C_FIXED in gennvm_get_lun
>>>> -add target creation flags check
>>>> -rebase to v4.5-rc1
>>>>
>>>> drivers/lightnvm/core.c | 36 ++++---
>>>> drivers/lightnvm/gennvm.c | 42 ++++++++-
>>>> drivers/lightnvm/rrpc.c | 215 +++++++++++++++++++++++++++---------------
>>>> drivers/lightnvm/rrpc.h | 6 +-
>>>> include/linux/lightnvm.h | 24 ++++-
>>>> include/uapi/linux/lightnvm.h | 3 +
>>>> 6 files changed, 229 insertions(+), 97 deletions(-)
>>>>
>>>
>>> Hi Wenwei,
>>>
>>> I did some digging on the patch and changed the interface to a
>>> reserve/release interface. I also removed the logic to dynamically
>>> select another lun than the one requested.
>>>
>>> A couple of questions:
>>>
>>> 1. The rrpc_lun->rev_lock and rev_trans_map change; this might be for
>>> another patch, and it isn't directly related to continuous mapping?
>>
>> rrpc_lun->rev_lock and rev_trans_map change is related to
>> non-continuous mapping, it's not directly related to continuous
>> mapping.
>> Put this change in another patch along with non-continuous mapping
>> support and this patch would be only add reserve/release thing, is
>> that your suggestion?
>
> Yes, that would be great. Then we keep it separate. I'll like to do some
> benchmarks with the patch on and off, to see the performance difference.
>
>>
>>> 2. Instead of dynamically assigning new luns when not available, what
>>> about taking a list of lun ids instead?
>>>
>>
>> Seems you prefer user make the choice ?
>
> Yes, I want it to be deterministic. For example, if we do it
> dynamically, the user might first allocate 2-4, and then allocate 1-3 ,
> which will actually allocate 0,1,5. Then later, a user tries to allocate
> on 0, and instead gets returned 6. It quickly makes it difficult to use.
>
>> But the target creation can still fail if one of the list lun ids is
>> not available although there may be enough free luns.
>
> Agree, the user would have to look up the free luns and then resubmit
> the target allocation.