Re: [RFC 4/5] MMC: Adjust unaligned write accesses.

[Andrei Warkentin <andreiw@motorola.com>]

On Fri, Mar 11, 2011 at 4:23 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Friday 11 March 2011, Andrei Warkentin wrote:
>> > I also don't know what the effect of setting physical_block_size
>> > and/or io_min is, possibly it no longer works if they are larger
>> > than the MMU page size. Need to try this.
>>
>> The other thing is figuring out the default size limit for when the
>> page align should be performed. I suppose it's safe enough to
>> set it to 1.5 size the super_page_size. But that number came from the
>> Toshiba card tests. Or it could be unbounded by default. I'd rather do
>> the later.
>
> You mean always splitting (multiples of) full super-pages from partial
> super-pages when the quirk flag is enabled?
>
> I think it depends on the performance numbers. Do you have any
> meaningful measurements without the quirk, with the current implementation
> and with the unbounded case?
>
> If the latter two are not much different on the toshiba card, that
> would be a simpler implementation, and more likely to be useful on
> other cards.
>

Revalidating the data now, along with some more tests, to get a better
picture. It seems the more data I get, the less it makes sense :(.

> I think we should also do measurements to see if the same quirk
> actually has any negative effects on other cards, or if there
> are even cases where it helps.

Going to test on Sandisk eMMC as well.

Thanks,
A