Re: [PATCH v8 1/2] mmc: add packed command feature of eMMC4.5

[merez@codeaurora.org]

On Tue, July 10, 2012 12:33 am, Chris Ball wrote:
> Hi,
>
> On Tue, Jul 10 2012, merez@codeaurora.org wrote:
>>> Sorry, I don't have a copy of the eMMC 4.5 spec -- is PACKED_EVENT_EN
>>> a one-time programmable fuse on the eMMC, like BKOPS_ENABLE was?
>>
>> No, it's not.
>
> Excellent, thanks.
>
> I've pushed both v8 patches to mmc-next.  Before pushing it up to Linus,
> I'd like to get a better idea of the variety of performances differences
> seen using packed writes -- has it been tried on devices from multiple
> eMMC vendors, and multiple host controller vendors?  Can we try to build
> up a quick table of results, with a standard test like iozone, to check
> that we've got decent test coverage?  Seungwon suggests using:
>
> iozone -az -i0 -I -s 10m -f /target/test -e
>
> I'm also worried about how much code this is adding, but I agree that
> it's worth it if the performance benefits are as described.
>
> Thanks,
>
> - Chris.
> --
> Chris Ball   <cjb@laptop.org>   <http://printf.net/>
> One Laptop Per Child
> --

Hi Chris,

I suggest to also use lmdd as a benchmark test for write packing, since
write packing is mostly beneficial in long sequential operations.
It can be used as follows:
lmdd if=internal of=/data/file1 bs=128k count=3000

Thanks,
Maya
-- 
Sent by consultant of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum