Re: [lc-devel] Chunk list issues

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

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?

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
>
>
>