lkml.org 
[lkml]   [2013]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Questin about swap_slot free and invalidate page
On 02/22/2013 05:42 AM, Dan Magenheimer wrote:
>> 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:
>>>> From: Ric Mason [mailto:ric.masonn@gmail.com]
>>>>> 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.

Thanks for your point out. Pers pages can have duplicate put since swap
cache page can be reused. Can eph pages also have duplicate put? If yes,
when can happen?

>



\
 
 \ /
  Last update: 2013-02-22 05:01    [W:0.093 / U:1.400 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site