Re: [[v4] 2/5] MMC: Use CMD23 for multiblock transfers when we can.

From: Jaehoon Chung <jh80.chung@samsung.com>
To: Andrei Warkentin <andreiw@motorola.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>,
	linux-mmc@vger.kernel.org, arindam.nath@amd.com, cjb@laptop.org,
	arnd@arndb.de, Kyungmin Park <kyungmin.park@samsung.com>,
	"Gao, Yunpeng" <yunpeng.gao@intel.com>
Subject: Re: [[v4] 2/5] MMC: Use CMD23 for multiblock transfers when we can.
Date: Fri, 20 May 2011 18:05:41 +0900	[thread overview]
Message-ID: <4DD62EE5.8040604@samsung.com> (raw)
In-Reply-To: <BANLkTi=mpibUJLJTCcf+i7=PgPBUFecgRw@mail.gmail.com>

Andrei Warkentin wrote:
> On Fri, May 20, 2011 at 1:49 AM, Andrei Warkentin <andreiw@motorola.com> wrote:
>> On Thu, May 19, 2011 at 11:38 PM, Jaehoon Chung <jh80.chung@samsung.com> wrote:
>>> Hi Andrei,
>>>
>>> Andrei Warkentin wrote:
>>>> On Wed, May 18, 2011 at 9:37 PM, Jaehoon Chung <jh80.chung@samsung.com> wrote:
>>>>> Hi Andrei
>>>>>
>>>>> Andrei Warkentin wrote:
>>>>>> CMD23-prefixed instead of open-ended multiblock transfers
>>>>>> have a performance advantage on some MMC cards.
>>>>>>
>>>>> you mentioned about "some MMC cards".
>>>>> Conversely, that means the some card didn't have a performance advantage?
>>>>>
>>>>> Did you find the performance advantage?
>>>>> if you found the advantage and you can tell me,
>>>>> i want to know what do you have the some MMC cards..
>>>>>
>>>> I've tested this on a Sandisk eMMC where I saw as good as
>>>> a 50% improvement on writes (30% real-life use cases). This was a
>>>> SEM32G 4.3+ part.
>>> Can you tell me your environment? buswidth, AP information, benchmark etc..
>>> And if you have the performance result's data, can you share them?
>>>
>> This was on an SDHCI controller (hence the patch...) on a Tegra
>> 2-based system. I was measuring
>> throughput on reads and writes (obviously without block cache,
>> filesystem, etc) to an eMMC card, 8 bits.
>>
>> Tested both with my tool (https://github.com/andreiw/superalign) and
>> an sqllite-based test.
>>
>> I'm attaching the data I have.
>>
>> A
>>
> 
> Additionally, CMD23 use is a requirement for SDXC cards (Arindam can
> comment on that), as well as for MMC reliable writes and eMMC 4.5-spec
> features (Yunpeng Gao can comment on that).
> 
> These patches allow CMD23 use. They do involve a some changes to host
> controller because of interaction with CMD12, as well as Auto-CMD12
> and Auto-CMD23 features. I can definitely consult you if you need help
> implementing CMD23 support for whatever controller you develop for.
> 

I used two host-controller (sdhci and dw_mmc). you implemented them in sdhci.
I applied your patch then tested CMD23...but i didn't applied  auto-CMD23.
I known that auto-CMD23 supported at SD3.0..right?
My controller is supported SD2.0..

If you can consult me, too much helpful to me..

Regards,
Jaehoon Chung