linux-kernel - Re: [PATCH 3/6] zsmalloc: rename zspage_order with zspage

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Date:	Wed, 25 Apr 2012 09:03:48 -0400
From:	Nitin Gupta <ngupta@...are.org>
To:	Minchan Kim <minchan@...nel.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 3/6] zsmalloc: rename zspage_order with zspage_pages

On 04/25/2012 02:23 AM, Minchan Kim wrote:

> zspage_order defines how many pages are needed to make a zspage.
> So _order_ is rather awkward naming. It already deceive Jonathan
> - http://lwn.net/Articles/477067/
> " For each size, the code calculates an optimum number of pages (up to 16)"
> 
> Let's change from _order_ to _pages_.
> 
> Signed-off-by: Minchan Kim <minchan@...nel.org>
> ---
>  drivers/staging/zsmalloc/zsmalloc-main.c |   14 +++++++-------
>  drivers/staging/zsmalloc/zsmalloc_int.h  |    2 +-
>  2 files changed, 8 insertions(+), 8 deletions(-)
>


Recently, Seth changed max_zspage_order to ZS_MAX_PAGES_PER_ZSPAGE for
the same reason. I think it would be better to rename the function in a
similary way to have some consistency. So, we could use:

1) get_pages_per_zspage() instead of get_zspage_pages()
2) class->pages_per_zspage instead of class->zspage_pages

 
> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
> index b99ad9e..0fe4cbb 100644
> --- a/drivers/staging/zsmalloc/zsmalloc-main.c
> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c
> @@ -180,7 +180,7 @@ out:
>   * link together 3 PAGE_SIZE sized pages to form a zspage
>   * since then we can perfectly fit in 8 such objects.
>   */
> -static int get_zspage_order(int class_size)
> +static int get_zspage_pages(int class_size)
>  {
>  	int i, max_usedpc = 0;
>  	/* zspage order which gives maximum used size per KB */
> @@ -368,7 +368,7 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
>  	 * identify the last page.
>  	 */
>  	error = -ENOMEM;
> -	for (i = 0; i < class->zspage_order; i++) {
> +	for (i = 0; i < class->zspage_pages; i++) {
>  		struct page *page, *prev_page;
>  
>  		page = alloc_page(flags);
> @@ -388,7 +388,7 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
>  			page->first_page = first_page;
>  		if (i >= 2)
>  			list_add(&page->lru, &prev_page->lru);
> -		if (i == class->zspage_order - 1)	/* last page */
> +		if (i == class->zspage_pages - 1)	/* last page */
>  			SetPagePrivate2(page);
>  		prev_page = page;
>  	}
> @@ -397,7 +397,7 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
>  
>  	first_page->freelist = obj_location_to_handle(first_page, 0);
>  	/* Maximum number of objects we can store in this zspage */
> -	first_page->objects = class->zspage_order * PAGE_SIZE / class->size;
> +	first_page->objects = class->zspage_pages * PAGE_SIZE / class->size;
>  
>  	error = 0; /* Success */
>  
> @@ -511,7 +511,7 @@ struct zs_pool *zs_create_pool(const char *name, gfp_t flags)
>  		class->size = size;
>  		class->index = i;
>  		spin_lock_init(&class->lock);
> -		class->zspage_order = get_zspage_order(size);
> +		class->zspage_pages = get_zspage_pages(size);
>  
>  	}
>  
> @@ -602,7 +602,7 @@ void *zs_malloc(struct zs_pool *pool, size_t size)
>  
>  		set_zspage_mapping(first_page, class->index, ZS_EMPTY);
>  		spin_lock(&class->lock);
> -		class->pages_allocated += class->zspage_order;
> +		class->pages_allocated += class->zspage_pages;
>  	}
>  
>  	obj = first_page->freelist;
> @@ -657,7 +657,7 @@ void zs_free(struct zs_pool *pool, void *obj)
>  	fullness = fix_fullness_group(pool, first_page);
>  
>  	if (fullness == ZS_EMPTY)
> -		class->pages_allocated -= class->zspage_order;
> +		class->pages_allocated -= class->zspage_pages;
>  
>  	spin_unlock(&class->lock);
>  
> diff --git a/drivers/staging/zsmalloc/zsmalloc_int.h b/drivers/staging/zsmalloc/zsmalloc_int.h
> index 92eefc6..8f9ce0c 100644
> --- a/drivers/staging/zsmalloc/zsmalloc_int.h
> +++ b/drivers/staging/zsmalloc/zsmalloc_int.h
> @@ -124,7 +124,7 @@ struct size_class {
>  	unsigned int index;
>  
>  	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
> -	int zspage_order;
> +	int zspage_pages;
>  
>  	spinlock_t lock;
>  


Thanks,
Nitin
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