Re: [PATCH v12 02/11] mm, swap: Add infrastructure for saving page metadata on swap

[Dave Hansen]

On 03/05/2018 11:29 AM, Khalid Aziz wrote:
> ADI data is per page data and is held in the spare bits in the RAM. It
> is loaded into the cache when data is loaded from RAM and flushed out to
> spare bits in the RAM when data is flushed from cache. Sparc allows one
> tag for each ADI block size of data and ADI block size is same as
> cacheline size.

Which does not square with your earlier assertion "ADI data is per page
data".  It's per-cacheline data.  Right?

> When a page is loaded into RAM from swap space, all of
> the associated ADI data for the page must also be loaded into the RAM,
> so it looks like page level data and storing it in page level software
> data structure makes sense. I am open to other suggestions though.

Do you have a way to tell that data is not being thrown away?  Like if
the ADI metadata is different for two different cachelines within a
single page?