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

[Chris Ball <cjb@laptop.org>]

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