linux-kernel - Re: [PATCH v1 09/19] zsmalloc: keep max_object in size

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Message-ID: <20160314045511.GA6159@bbox>
Date:	Mon, 14 Mar 2016 13:55:11 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	xuyiping <xuyiping@...ilicon.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, jlayton@...chiereds.net,
	bfields@...ldses.org, Vlastimil Babka <vbabka@...e.cz>,
	Joonsoo Kim <iamjoonsoo.kim@....com>, koct9i@...il.com,
	aquini@...hat.com, virtualization@...ts.linux-foundation.org,
	Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	rknize@...orola.com, Rik van Riel <riel@...hat.com>,
	Gioh Kim <gurugio@...mail.net>
Subject: Re: [PATCH v1 09/19] zsmalloc: keep max_object in size_class

On Sat, Mar 12, 2016 at 09:44:48AM +0800, xuyiping wrote:
> 
> 
> On 2016/3/11 15:30, Minchan Kim wrote:
> >Every zspage in a size_class has same number of max objects so
> >we could move it to a size_class.
> >
> >Signed-off-by: Minchan Kim <minchan@...nel.org>
> >---
> >  mm/zsmalloc.c | 29 ++++++++++++++---------------
> >  1 file changed, 14 insertions(+), 15 deletions(-)
> >
> >diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> >index b4fb11831acb..ca663c82c1fc 100644
> >--- a/mm/zsmalloc.c
> >+++ b/mm/zsmalloc.c
> >@@ -32,8 +32,6 @@
> >   *	page->freelist: points to the first free object in zspage.
> >   *		Free objects are linked together using in-place
> >   *		metadata.
> >- *	page->objects: maximum number of objects we can store in this
> >- *		zspage (class->zspage_order * PAGE_SIZE / class->size)
> >   *	page->lru: links together first pages of various zspages.
> >   *		Basically forming list of zspages in a fullness group.
> >   *	page->mapping: class index and fullness group of the zspage
> >@@ -211,6 +209,7 @@ struct size_class {
> >  	 * of ZS_ALIGN.
> >  	 */
> >  	int size;
> >+	int objs_per_zspage;
> >  	unsigned int index;
> >
> >  	struct zs_size_stat stats;
> >@@ -622,21 +621,22 @@ static inline void zs_pool_stat_destroy(struct zs_pool *pool)
> >   * the pool (not yet implemented). This function returns fullness
> >   * status of the given page.
> >   */
> >-static enum fullness_group get_fullness_group(struct page *first_page)
> >+static enum fullness_group get_fullness_group(struct size_class *class,
> >+						struct page *first_page)
> >  {
> >-	int inuse, max_objects;
> >+	int inuse, objs_per_zspage;
> >  	enum fullness_group fg;
> >
> >  	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> >
> >  	inuse = first_page->inuse;
> >-	max_objects = first_page->objects;
> >+	objs_per_zspage = class->objs_per_zspage;
> >
> >  	if (inuse == 0)
> >  		fg = ZS_EMPTY;
> >-	else if (inuse == max_objects)
> >+	else if (inuse == objs_per_zspage)
> >  		fg = ZS_FULL;
> >-	else if (inuse <= 3 * max_objects / fullness_threshold_frac)
> >+	else if (inuse <= 3 * objs_per_zspage / fullness_threshold_frac)
> >  		fg = ZS_ALMOST_EMPTY;
> >  	else
> >  		fg = ZS_ALMOST_FULL;
> >@@ -723,7 +723,7 @@ static enum fullness_group fix_fullness_group(struct size_class *class,
> >  	enum fullness_group currfg, newfg;
> >
> >  	get_zspage_mapping(first_page, &class_idx, &currfg);
> >-	newfg = get_fullness_group(first_page);
> >+	newfg = get_fullness_group(class, first_page);
> >  	if (newfg == currfg)
> >  		goto out;
> >
> >@@ -1003,9 +1003,6 @@ static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
> >  	init_zspage(class, first_page);
> >
> >  	first_page->freelist = location_to_obj(first_page, 0);
> >-	/* Maximum number of objects we can store in this zspage */
> >-	first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
> >-
> >  	error = 0; /* Success */
> >
> >  cleanup:
> >@@ -1235,11 +1232,11 @@ static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
> >  	return true;
> >  }
> >
> >-static bool zspage_full(struct page *first_page)
> >+static bool zspage_full(struct size_class *class, struct page *first_page)
> >  {
> >  	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> >
> >-	return first_page->inuse == first_page->objects;
> >+	return first_page->inuse == class->objs_per_zspage;
> >  }
> >
> >  unsigned long zs_get_total_pages(struct zs_pool *pool)
> >@@ -1625,7 +1622,7 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
> >  		}
> >
> >  		/* Stop if there is no more space */
> >-		if (zspage_full(d_page)) {
> >+		if (zspage_full(class, d_page)) {
> >  			unpin_tag(handle);
> >  			ret = -ENOMEM;
> >  			break;
> >@@ -1684,7 +1681,7 @@ static enum fullness_group putback_zspage(struct zs_pool *pool,
> >  {
> >  	enum fullness_group fullness;
> >
> >-	fullness = get_fullness_group(first_page);
> >+	fullness = get_fullness_group(class, first_page);
> >  	insert_zspage(class, fullness, first_page);
> >  	set_zspage_mapping(first_page, class->index, fullness);
> >
> >@@ -1933,6 +1930,8 @@ struct zs_pool *zs_create_pool(const char *name, gfp_t flags)
> >  		class->size = size;
> >  		class->index = i;
> >  		class->pages_per_zspage = pages_per_zspage;
> >+		class->objs_per_zspage = class->pages_per_zspage *
> >+						PAGE_SIZE / class->size;
> >  		if (pages_per_zspage == 1 &&
> >  			get_maxobj_per_zspage(size, pages_per_zspage) == 1)
> >  			class->huge = true;
> 
> 		computes the "objs_per_zspage" twice here.
> 
> 		class->objs_per_zspage = get_maxobj_per_zspage(size,
> 						pages_per_zspage);
> 		if (pages_per_zspage == 1 && class->objs_per_zspage ==1)
> 			class->huge = true;

Yeb. I will do.

Thanks.