[linux-mm-cc] Re: [lc-devel] Chunk list issues

[Nitin Gupta]

Hi Anderson,

> 
>> On 6/28/06, Anderson Briglia <briglia.anderson at gmail.com> wrote:
>> > > > I have a doubt related to chunk operations:
>> > > >
>> > > > - I guess you will use the virtual swap as the compressed cache for
>> > > > anon pages, right? If yes, how will you swapin/swapout chunks? If a
>> > > > single chunk points to a portion of a physical page, and the
>> > > > swapin/swapout operations handle entire pages of data.
>> > >
>> > > Yes, vswap is for anon pages. I think you are mistaken 
>> somewhere...I'm not using
>> > > bio structs or anything to swapin/out pages from vswap.
>> >
>> > Ok. Will be possible to transfer pages from vswap to a 'real' swap 
>> area?
>> >
>>
>> Yes, but 'procedure' will be same as for transferring a page from a
>> swap to any other swap: change it swp_entry_t to have 'type' for other
>> swap and it will get written to this second swap.
> 
> What will be the factor that determines when/which page will be
> migrated from vswap to real swap?
>

vswap is full. Maybe others but I haven't thought of them yet :P

> How the chk->count is increased or decreased? Is this count related to
> page->_count?
> 

chk->_count has same purpose as page->_count. When you use a chunk you take a 
count. When you no longer want it you decrement the count. When it goes 0, free it.


I hope to post an implementation of compression structure (as on wiki) by 
Sunday. Its as a separate module (storage-test). After a bit of testing I will 
merge it with main ccaching code.
This will also allow working on structure separately from rest of ccaching 
details :)

Cheers,
Nitin Gupta