linux-kernel - Re: [PATCH v4 00/14] mpt3sas driver NVMe support:

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Date:   Wed, 13 Sep 2017 12:45:06 +0530
From:   Suganath Prabu Subramani <suganath-prabu.subramani@...adcom.com>
To:     "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-scsi@...r.kernel.org,
        Sathya Prakash <Sathya.Prakash@...adcom.com>,
        Kashyap Desai <kashyap.desai@...adcom.com>,
        linux-kernel@...r.kernel.org,
        Chaitra Basappa <chaitra.basappa@...adcom.com>,
        Sreekanth Reddy <sreekanth.reddy@...adcom.com>,
        linux-nvme@...ts.infradead.org
Subject: Re: [PATCH v4 00/14] mpt3sas driver NVMe support:

Hi Martin,

Is there any update on the submitted mpt3sas patches.

Thanks,
Suganath Prabu S

On Fri, Sep 1, 2017 at 2:09 PM, Suganath Prabu Subramani
<suganath-prabu.subramani@...adcom.com> wrote:
> Hi Martin,
>
> On Fri, Sep 1, 2017 at 8:52 AM, Martin K. Petersen
> <martin.petersen@...cle.com> wrote:
>>
>> Hi Suganath,
>>
>>> Let me explain - NVME device fast path is possible in two ways.  IEEE
>>> SGL and PRP SGL. Due to h/w constraint we choose IEEE SGL only for
>>> smaller IO size.  Both above is true h/w Fast Path and no firmware
>>> involvement.
>>
>>> Agree with you. We are planning to see if we can keep only simple Fast
>>> Path using only PRP.
>>
>> That would be great, thank you!
>>
>>> Currently there is no performance issue for UNMAP translation in FW.
>>
>> Good!
>>
>>>> And yet patch 4 circumvents that statement by adding support for
>>>> encapsulated commands to bypass the FW translation...
>>>
>>> This path is not due to performance reason. User wants to interact
>>> with NVME drive in native NVME command for management.
>>
>> Patch 4 states:
>>
>> "This encapsulated NVMe command is used by applications to send direct
>> NVMe commands to NVMe drives or for handling unmap where the translation
>> at controller/firmware level is having performance issues."
>>
>> --
>
> The statement in description of patch 4 is added by mistake, We ll
> correct the description and re sending that.
>
>> Martin K. Petersen      Oracle Linux Engineering
>
> Thanks,
> Suganath Prabu S