From: Ric Mason [mailto:ric.masonn@gmail.com]
Subject: Re: Questin about swap_slot free and invalidate page

On 02/19/2013 11:27 PM, Dan Magenheimer wrote:

quoted

quoted

From: Ric Mason [mailto:ric.masonn@gmail.com]

quoted

Hugh is right that handling the possibility of duplicates is
part of the tmem ABI.  If there is any possibility of duplicates,
the ABI defines how a backend must handle them to avoid data
coherency issues.

The kernel implements an in-kernel API which implements the tmem
ABI.  If the frontend and backend can always agree that duplicate

Which ABI in zcache implement that?

https://oss.oracle.com/projects/tmem/dist/documentation/api/tmemspec-v001.pdf

The in-kernel APIs are frontswap and cleancache.  For more information about
tmem, see http://lwn.net/Articles/454795/

But you mentioned that you have in-kernel API which can handle
duplicate.  Do you mean zcache_cleancache/frontswap_put_page? I think
they just overwrite instead of optional flush the page on the
second(duplicate) put as mentioned in your tmemspec.

Maybe I am misunderstanding your question...  The spec allows
overwrite (and return success) OR flush the page (and return
failure).  Zcache does the latter (flush).  The code that implements
it is in tmem_put.

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