Unexpected issues with 2 NVME initiators using the same target

[maxg@mellanox.com (Max Gurtovoy)]

On 3/13/2017 11:43 AM, Sagi Grimberg wrote:
>
>> Patched  by patch of Max (block 4K):
>>
>> allways reg          Y                N
>> write              1902K            1923.3K
>> read               1315K            2009K
>>
>> Original  OFED code (block 4K)
>>
>> allways reg          Y                N
>> write              1947K           1982K
>> read               1273K
>> 1978K
>
> First, the write comparison is redundant because
> we send immediate data without memory registration.
>
> And, I'd compare against upstream code and not OFED.

I dont thing we'll get different results (my first tests were with nvmf 
upstream driver).

>
> So it seems that strong fencing does not effect performance
> from the ULP point of view, surprising...
> I'd suggest comparing on nvmf and srp as well.

I agree. We also want to run other application types with it in our 
performance lab.

>
> If this is the case, and it indeed resolves the issue, we
> should move forward with it as is.

Not as is, because it will have influence on ConnectX5 too (no need).
We'll need to update the patch before submission.