Commit bfd093f5 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds

zsmalloc: use freeobj for index

Zsmalloc stores first free object's <PFN, obj_idx> position into freeobj
in each zspage.  If we change it with index from first_page instead of
position, it makes page migration simple because we don't need to
correct other entries for linked list if a page is migrated out.

Link: http://lkml.kernel.org/r/1464736881-24886-11-git-send-email-minchan@kernel.orgSigned-off-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4aa409ca
......@@ -71,9 +71,7 @@
* Object location (<PFN>, <obj_idx>) is encoded as
* as single (unsigned long) handle value.
*
* Note that object index <obj_idx> is relative to system
* page <PFN> it is stored in, so for each sub-page belonging
* to a zspage, obj_idx starts with 0.
* Note that object index <obj_idx> starts from 0.
*
* This is made more complicated by various memory models and PAE.
*/
......@@ -214,10 +212,10 @@ struct size_class {
struct link_free {
union {
/*
* Position of next free chunk (encodes <PFN, obj_idx>)
* Free object index;
* It's valid for non-allocated object
*/
void *next;
unsigned long next;
/*
* Handle of allocated object.
*/
......@@ -261,7 +259,7 @@ struct zspage {
unsigned int class:CLASS_BITS;
};
unsigned int inuse;
void *freeobj;
unsigned int freeobj;
struct page *first_page;
struct list_head list; /* fullness list */
};
......@@ -459,14 +457,14 @@ static inline void set_first_obj_offset(struct page *page, int offset)
page->index = offset;
}
static inline unsigned long get_freeobj(struct zspage *zspage)
static inline unsigned int get_freeobj(struct zspage *zspage)
{
return (unsigned long)zspage->freeobj;
return zspage->freeobj;
}
static inline void set_freeobj(struct zspage *zspage, unsigned long obj)
static inline void set_freeobj(struct zspage *zspage, unsigned int obj)
{
zspage->freeobj = (void *)obj;
zspage->freeobj = obj;
}
static void get_zspage_mapping(struct zspage *zspage,
......@@ -810,6 +808,10 @@ static int get_pages_per_zspage(int class_size)
return max_usedpc_order;
}
static struct page *get_first_page(struct zspage *zspage)
{
return zspage->first_page;
}
static struct zspage *get_zspage(struct page *page)
{
......@@ -821,37 +823,33 @@ static struct page *get_next_page(struct page *page)
return page->next;
}
/*
* Encode <page, obj_idx> as a single handle value.
* We use the least bit of handle for tagging.
/**
* obj_to_location - get (<page>, <obj_idx>) from encoded object value
* @page: page object resides in zspage
* @obj_idx: object index
*/
static void *location_to_obj(struct page *page, unsigned long obj_idx)
static void obj_to_location(unsigned long obj, struct page **page,
unsigned int *obj_idx)
{
unsigned long obj;
obj >>= OBJ_TAG_BITS;
*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
*obj_idx = (obj & OBJ_INDEX_MASK);
}
if (!page) {
VM_BUG_ON(obj_idx);
return NULL;
}
/**
* location_to_obj - get obj value encoded from (<page>, <obj_idx>)
* @page: page object resides in zspage
* @obj_idx: object index
*/
static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)
{
unsigned long obj;
obj = page_to_pfn(page) << OBJ_INDEX_BITS;
obj |= ((obj_idx) & OBJ_INDEX_MASK);
obj |= obj_idx & OBJ_INDEX_MASK;
obj <<= OBJ_TAG_BITS;
return (void *)obj;
}
/*
* Decode <page, obj_idx> pair from the given object handle. We adjust the
* decoded obj_idx back to its original value since it was adjusted in
* location_to_obj().
*/
static void obj_to_location(unsigned long obj, struct page **page,
unsigned long *obj_idx)
{
obj >>= OBJ_TAG_BITS;
*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
*obj_idx = (obj & OBJ_INDEX_MASK);
return obj;
}
static unsigned long handle_to_obj(unsigned long handle)
......@@ -869,16 +867,6 @@ static unsigned long obj_to_head(struct size_class *class, struct page *page,
return *(unsigned long *)obj;
}
static unsigned long obj_idx_to_offset(struct page *page,
unsigned long obj_idx, int class_size)
{
unsigned long off;
off = get_first_obj_offset(page);
return off + obj_idx * class_size;
}
static inline int trypin_tag(unsigned long handle)
{
return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
......@@ -922,13 +910,13 @@ static void free_zspage(struct zs_pool *pool, struct zspage *zspage)
/* Initialize a newly allocated zspage */
static void init_zspage(struct size_class *class, struct zspage *zspage)
{
unsigned int freeobj = 1;
unsigned long off = 0;
struct page *page = zspage->first_page;
while (page) {
struct page *next_page;
struct link_free *link;
unsigned int i = 1;
void *vaddr;
set_first_obj_offset(page, off);
......@@ -937,7 +925,7 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
link = (struct link_free *)vaddr + off / sizeof(*link);
while ((off += class->size) < PAGE_SIZE) {
link->next = location_to_obj(page, i++);
link->next = freeobj++ << OBJ_ALLOCATED_TAG;
link += class->size / sizeof(*link);
}
......@@ -947,14 +935,21 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
* page (if present)
*/
next_page = get_next_page(page);
link->next = location_to_obj(next_page, 0);
if (next_page) {
link->next = freeobj++ << OBJ_ALLOCATED_TAG;
} else {
/*
* Reset OBJ_ALLOCATED_TAG bit to last link to tell
* whether it's allocated object or not.
*/
link->next = -1 << OBJ_ALLOCATED_TAG;
}
kunmap_atomic(vaddr);
page = next_page;
off %= PAGE_SIZE;
}
set_freeobj(zspage,
(unsigned long)location_to_obj(zspage->first_page, 0));
set_freeobj(zspage, 0);
}
static void create_page_chain(struct zspage *zspage, struct page *pages[],
......@@ -1271,7 +1266,8 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
{
struct zspage *zspage;
struct page *page;
unsigned long obj, obj_idx, off;
unsigned long obj, off;
unsigned int obj_idx;
unsigned int class_idx;
enum fullness_group fg;
......@@ -1295,7 +1291,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
zspage = get_zspage(page);
get_zspage_mapping(zspage, &class_idx, &fg);
class = pool->size_class[class_idx];
off = obj_idx_to_offset(page, obj_idx, class->size);
off = (class->size * obj_idx) & ~PAGE_MASK;
area = &get_cpu_var(zs_map_area);
area->vm_mm = mm;
......@@ -1324,7 +1320,8 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
{
struct zspage *zspage;
struct page *page;
unsigned long obj, obj_idx, off;
unsigned long obj, off;
unsigned int obj_idx;
unsigned int class_idx;
enum fullness_group fg;
......@@ -1336,7 +1333,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
zspage = get_zspage(page);
get_zspage_mapping(zspage, &class_idx, &fg);
class = pool->size_class[class_idx];
off = obj_idx_to_offset(page, obj_idx, class->size);
off = (class->size * obj_idx) & ~PAGE_MASK;
area = this_cpu_ptr(&zs_map_area);
if (off + class->size <= PAGE_SIZE)
......@@ -1358,21 +1355,28 @@ EXPORT_SYMBOL_GPL(zs_unmap_object);
static unsigned long obj_malloc(struct size_class *class,
struct zspage *zspage, unsigned long handle)
{
int i, nr_page, offset;
unsigned long obj;
struct link_free *link;
struct page *m_page;
unsigned long m_objidx, m_offset;
unsigned long m_offset;
void *vaddr;
handle |= OBJ_ALLOCATED_TAG;
obj = get_freeobj(zspage);
obj_to_location(obj, &m_page, &m_objidx);
m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
offset = obj * class->size;
nr_page = offset >> PAGE_SHIFT;
m_offset = offset & ~PAGE_MASK;
m_page = get_first_page(zspage);
for (i = 0; i < nr_page; i++)
m_page = get_next_page(m_page);
vaddr = kmap_atomic(m_page);
link = (struct link_free *)vaddr + m_offset / sizeof(*link);
set_freeobj(zspage, (unsigned long)link->next);
set_freeobj(zspage, link->next >> OBJ_ALLOCATED_TAG);
if (!class->huge)
/* record handle in the header of allocated chunk */
link->handle = handle;
......@@ -1384,6 +1388,8 @@ static unsigned long obj_malloc(struct size_class *class,
mod_zspage_inuse(zspage, 1);
zs_stat_inc(class, OBJ_USED, 1);
obj = location_to_obj(m_page, obj);
return obj;
}
......@@ -1449,22 +1455,22 @@ static void obj_free(struct size_class *class, unsigned long obj)
struct link_free *link;
struct zspage *zspage;
struct page *f_page;
unsigned long f_objidx, f_offset;
unsigned long f_offset;
unsigned int f_objidx;
void *vaddr;
obj &= ~OBJ_ALLOCATED_TAG;
obj_to_location(obj, &f_page, &f_objidx);
f_offset = (class->size * f_objidx) & ~PAGE_MASK;
zspage = get_zspage(f_page);
f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
vaddr = kmap_atomic(f_page);
/* Insert this object in containing zspage's freelist */
link = (struct link_free *)(vaddr + f_offset);
link->next = (void *)get_freeobj(zspage);
link->next = get_freeobj(zspage) << OBJ_ALLOCATED_TAG;
kunmap_atomic(vaddr);
set_freeobj(zspage, obj);
set_freeobj(zspage, f_objidx);
mod_zspage_inuse(zspage, -1);
zs_stat_dec(class, OBJ_USED, 1);
}
......@@ -1473,7 +1479,8 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
{
struct zspage *zspage;
struct page *f_page;
unsigned long obj, f_objidx;
unsigned long obj;
unsigned int f_objidx;
int class_idx;
struct size_class *class;
enum fullness_group fullness;
......@@ -1510,7 +1517,7 @@ static void zs_object_copy(struct size_class *class, unsigned long dst,
unsigned long src)
{
struct page *s_page, *d_page;
unsigned long s_objidx, d_objidx;
unsigned int s_objidx, d_objidx;
unsigned long s_off, d_off;
void *s_addr, *d_addr;
int s_size, d_size, size;
......@@ -1521,8 +1528,8 @@ static void zs_object_copy(struct size_class *class, unsigned long dst,
obj_to_location(src, &s_page, &s_objidx);
obj_to_location(dst, &d_page, &d_objidx);
s_off = obj_idx_to_offset(s_page, s_objidx, class->size);
d_off = obj_idx_to_offset(d_page, d_objidx, class->size);
s_off = (class->size * s_objidx) & ~PAGE_MASK;
d_off = (class->size * d_objidx) & ~PAGE_MASK;
if (s_off + class->size > PAGE_SIZE)
s_size = PAGE_SIZE - s_off;
......
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