RE: [PATCH] mmc: dw_mmc: Support predefined multiple block transfers.

Seungwon Jeon
2011-09-28T08:23:47Z

Andrei Warkentin wrote:
> 2011/9/26 Seungwon Jeon <tgih.jun@samsung.com>:
> > Andrei Warkentin wrote:
> >> Hi Seungwon,
> >>
> >> ----- Original Message -----
> >> > From: "Seungwon Jeon" <tgih.jun@samsung.com>
> >> > To: linux-mmc@vger.kernel.org
> >> > Cc: "Chris Ball" <cjb@laptop.org>, linux-samsung-soc@vger.kernel.org,
> >> "kgene kim" <kgene.kim@samsung.com>, "dh han"
> >> > <dh.han@samsung.com>, "Seungwon Jeon" <tgih.jun@samsung.com>
> >> > Sent: Monday, September 26, 2011 7:46:59 AM
> >> > Subject: [PATCH] mmc: dw_mmc: Support predefined multiple block
> >> transfers.
> >> >
> >> > This patch adds the support for predefined multiple block read/write.
> >> >
> >> > Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
> >>
> >> Without knowing much about dw_mmc host, your logic otherwise looks ok,
> >> given what
> >> I've previously done for SDHCI as far as CMD23/Auto-CMD23 enhancement.
> >> Just curious, what eMMC cards did you test this on, and what
> improvement
> >> did you see?
> >
> > Thank you for review.
> > As you done, predefined transfer is required for reliable writes and
> eMMC4.5 feature.
> > Sadly, I didn't gain an improvement in my case.
> > (I don't know whether I can clarify the tested eMMC card, just one
> sample.)
> >
>
> So far I've seen some Sandisk cards have a noticeable real-life
> improvement (30%) over
> open-ended transfers.
>
> You might wish to try out https://github.com/andreiw/superalign to be
> certain.

I had already tested this patch with IOZONE, but I found no difference.
Maybe a result depends on eMMC device.
As your recommend, I applied above benchmark tool.
Predefined transfer seems like a little better, but there is no difference.

Thanks.
Seungwon Jeon.

>
> A