Re: [lc-devel] Chunk list issues

[Mauricio L. <mau...@gm...>]

Hi Gupta,

I keep implementing some more functions related to chunk list operations.

If you have in mind functions that will be important in terms of chunk
list, let me know.

BR,

Mauricio Lin.

On 6/21/06, Nitin Gupta <nit...@gm...> wrote:
> Mauricio Lin wrote:
> > Hi Gupta,
> >
> > BTW, is there any special reason the related chunks are just
> > singly-linked list? Could they be also doubly-linked list as the
> > master chunk list?
> >
> > BR,
> >
> > Mauricio Lin.
> >
> > On 6/21/06, Mauricio Lin <mau...@gm...> wrote:
> >> Hi Gupta,
> >>
> >> I started to implement some basic operations related to chunk list
> >> (not finished yet). Take a look if such functions and macros can be
> >> useful.
> >>
> >> /* This works as the header of master chunk list*/
> >> struct chunk init_chunk = {
> >>         .start_addr = NULL,
> >>         .size = 0,
> >>         .next = NULL,
> >>         .chunks = LIST_HEAD_INIT(init_chunk.chunks)
> >> };
> >>
> >> #define next_chunk(chk) list_entry((chk)->chunks.next, struct chunk,
> >> chunks)
> >>
> >> #define prev_chunk(chk) list_entry((chk)->chunks.prev, struct chunk,
> >> chunks)
> >>
> >> #define for_each_chunk(chk) \
> >>         for (chk = &init_chunk ; (chk = next_chunk(chk)) !=
> >> &init_chunk ; )
> >>
> >> static inline void add_chunk_to_list(struct chunk *chk)
> >> {
> >>         list_add_tail(&chk->chunks, &init_chunk.chunks);
> >> }
> >>
> >> static inline void del_chunk_from_list(struct chunk *chk)
> >> {
> >>         list_del(&chk->chunks);
> >> }
> >>
> >> What do you think?
>
> These will be useful. Thanks.
>
> -- Nitin
>
> >>
> >> BR,
> >>
> >> Mauricio Lin.
> >>
> >>
> >> On 6/21/06, Nitin Gupta <nit...@gm...> wrote:
> >> > Hi Mauricio,
> >> >
> >> > Mauricio Lin wrote:
> >> > > On 6/21/06, Nitin Gupta <nit...@gm...> wrote:
> >> > >> Mauricio Lin wrote:
> >> > >> > Regarding the master chunk list (chunks) in the struct chunk,
> >> does it
> >> > >> > store the chunks of one page cache or several page caches? Will be
> >> > >> > there one master chunk list per page cache radix tree?
> >> > >>
> >> > >> 'master chunk list' is list of all chunks -- these chunks may be
> >> part
> >> > >> of a file,
> >> > >> part of anon page, or free chunks. Its there to easily merge
> >> > >> physically adjacent
> >> > >> chunks when a chunk is freed.
> >> > >
> >> > > You mean there will be one master chunk list for several page cache
> >> > > radix tree, right?
> >> > >
> >> >
> >> > Yes.
> >> > In other words: nodes of several page cache radix trees will be
> >> replaces by
> >> > chunk_head's. These chunk_head's point to corres. list of chunks.
> >> And all these
> >> > chunks are linked together by master chunk list (MCL).
> >> >
> >> > >>
> >> > >> >
> >> > >> > I also wonder where the chunk list header will be stored. For
> >> instance
> >> > >> > the list header of task_struct is stored in the tasks field of
> >> > >> > init_task, so when an insertion happens in the list of
> >> task_struct,
> >> > >> > something like that is used:
> >> > >> >
> >> > >> > list_add_tail(&p->tasks, &init_task.tasks);
> >> > >> >
> >> > >> > where the first argument is the element to be inserted and the
> >> second
> >> > >> > argument corresponds the list header of task_struct.
> >> > >> > Thus where the list header of chunks will be stored? Any idea?
> >> > >> >
> >> > >>
> >> > >> A compressed page is stored in many chunks.
> >> chunk_head->chunk_list is
> >> > >> made to
> >> > >> point to first of these chunks and these 'related' chunks are linked
> >> > >> together
> >> > >> using chunk->next
> >> > >
> >> > > OK, I know about the chunk_list purpose, but chunk_list is not the
> >> > > header of master chunk list, since it is not a list_head. What I am
> >> > > trying to say is if you want to add something in the master chunk
> >> > > list, you have to use a function as list_add_tail() (or similar
> >> one in
> >> > > include/linux/list.h) and a header list is needed for representing
> >> and
> >> > > manipulating the master chunk list. If you are going to add something
> >> > > in the master chunk list, certainly functions in include/linux/list.h
> >> > > need be used. Let's suppose that list_add_tail() function is used to
> >> > > insert a chunk in the list, so in this way something like this is
> >> > > used:
> >> > >
> >> > > list_add_tail(&chk->chunks, chunk_list_head);
> >> > >
> >> > > chk is a instance of struct chunk, where the field "chunks" is
> >> used to
> >> > > link to the list.
> >> > > chunk_list_head is the header of chunk list of type 'list_head'
> >> > > (because every list has a header)
> >> > >
> >> > > Such can be declared and initiliazed as:
> >> > > static LIST_HEAD(chunk_list_head);
> >> > >
> >> > > The chunk_list_head  (header of master chunk list) must be stored in
> >> > > some place. So my question is where it is going to be stored ?
> >> > >
> >> >
> >> > I was still stuck with 'related chunk list' (ok, RCL) while
> >> answering you :)
> >> > All these lists: MCL, LRU_{page_cache_clean,page_cache_dirty,anon},
> >> > Free_{good,bad,ugly} will have their heads as globals in mm/ccache.c
> >> >
> >> > Of these:
> >> > MCL lists use chunk->chunks (doubly linked)
> >> > LRU lists use chunk_head->lru (doubly linked)
> >> > Free lists use chunk->next (singly linked)
> >> >
> >> >
> >> > Cheers,
> >> > Nitin Gupta
> >> >
> >> >
> >> >
> >>
> >
>
>