mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-28 06:34:12 +08:00
z3fold: use per-page spinlock
Most of z3fold operations are in-page, such as modifying z3fold page header or moving z3fold objects within a page. Taking per-pool spinlock to protect per-page objects is therefore suboptimal, and the idea of having a per-page spinlock (or rwlock) has been around for some time. This patch implements spinlock-based per-page locking mechanism which is lightweight enough to normally fit ok into the z3fold header. Link: http://lkml.kernel.org/r/20170131214438.433e0a5fda908337b63206d3@gmail.com Signed-off-by: Vitaly Wool <vitalywool@gmail.com> Reviewed-by: Dan Streetman <ddstreet@ieee.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
1b096e5ae9
commit
2f1e5e4d84
150
mm/z3fold.c
150
mm/z3fold.c
@ -51,6 +51,7 @@ enum buddy {
|
||||
* struct z3fold_header - z3fold page metadata occupying the first chunk of each
|
||||
* z3fold page, except for HEADLESS pages
|
||||
* @buddy: links the z3fold page into the relevant list in the pool
|
||||
* @page_lock: per-page lock
|
||||
* @first_chunks: the size of the first buddy in chunks, 0 if free
|
||||
* @middle_chunks: the size of the middle buddy in chunks, 0 if free
|
||||
* @last_chunks: the size of the last buddy in chunks, 0 if free
|
||||
@ -58,6 +59,7 @@ enum buddy {
|
||||
*/
|
||||
struct z3fold_header {
|
||||
struct list_head buddy;
|
||||
spinlock_t page_lock;
|
||||
unsigned short first_chunks;
|
||||
unsigned short middle_chunks;
|
||||
unsigned short last_chunks;
|
||||
@ -148,6 +150,7 @@ static struct z3fold_header *init_z3fold_page(struct page *page)
|
||||
clear_bit(PAGE_HEADLESS, &page->private);
|
||||
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
|
||||
|
||||
spin_lock_init(&zhdr->page_lock);
|
||||
zhdr->first_chunks = 0;
|
||||
zhdr->middle_chunks = 0;
|
||||
zhdr->last_chunks = 0;
|
||||
@ -163,6 +166,19 @@ static void free_z3fold_page(struct z3fold_header *zhdr)
|
||||
__free_page(virt_to_page(zhdr));
|
||||
}
|
||||
|
||||
/* Lock a z3fold page */
|
||||
static inline void z3fold_page_lock(struct z3fold_header *zhdr)
|
||||
{
|
||||
spin_lock(&zhdr->page_lock);
|
||||
}
|
||||
|
||||
/* Unlock a z3fold page */
|
||||
static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
|
||||
{
|
||||
spin_unlock(&zhdr->page_lock);
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Encodes the handle of a particular buddy within a z3fold page
|
||||
* Pool lock should be held as this function accesses first_num
|
||||
@ -351,50 +367,60 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
|
||||
bud = HEADLESS;
|
||||
else {
|
||||
chunks = size_to_chunks(size);
|
||||
spin_lock(&pool->lock);
|
||||
|
||||
/* First, try to find an unbuddied z3fold page. */
|
||||
zhdr = NULL;
|
||||
for_each_unbuddied_list(i, chunks) {
|
||||
if (!list_empty(&pool->unbuddied[i])) {
|
||||
zhdr = list_first_entry(&pool->unbuddied[i],
|
||||
spin_lock(&pool->lock);
|
||||
zhdr = list_first_entry_or_null(&pool->unbuddied[i],
|
||||
struct z3fold_header, buddy);
|
||||
page = virt_to_page(zhdr);
|
||||
if (zhdr->first_chunks == 0) {
|
||||
if (zhdr->middle_chunks != 0 &&
|
||||
chunks >= zhdr->start_middle)
|
||||
bud = LAST;
|
||||
else
|
||||
bud = FIRST;
|
||||
} else if (zhdr->last_chunks == 0)
|
||||
bud = LAST;
|
||||
else if (zhdr->middle_chunks == 0)
|
||||
bud = MIDDLE;
|
||||
else {
|
||||
pr_err("No free chunks in unbuddied\n");
|
||||
WARN_ON(1);
|
||||
continue;
|
||||
}
|
||||
list_del(&zhdr->buddy);
|
||||
goto found;
|
||||
if (!zhdr) {
|
||||
spin_unlock(&pool->lock);
|
||||
continue;
|
||||
}
|
||||
list_del_init(&zhdr->buddy);
|
||||
spin_unlock(&pool->lock);
|
||||
|
||||
page = virt_to_page(zhdr);
|
||||
z3fold_page_lock(zhdr);
|
||||
if (zhdr->first_chunks == 0) {
|
||||
if (zhdr->middle_chunks != 0 &&
|
||||
chunks >= zhdr->start_middle)
|
||||
bud = LAST;
|
||||
else
|
||||
bud = FIRST;
|
||||
} else if (zhdr->last_chunks == 0)
|
||||
bud = LAST;
|
||||
else if (zhdr->middle_chunks == 0)
|
||||
bud = MIDDLE;
|
||||
else {
|
||||
spin_lock(&pool->lock);
|
||||
list_add(&zhdr->buddy, &pool->buddied);
|
||||
spin_unlock(&pool->lock);
|
||||
z3fold_page_unlock(zhdr);
|
||||
pr_err("No free chunks in unbuddied\n");
|
||||
WARN_ON(1);
|
||||
continue;
|
||||
}
|
||||
goto found;
|
||||
}
|
||||
bud = FIRST;
|
||||
spin_unlock(&pool->lock);
|
||||
}
|
||||
|
||||
/* Couldn't find unbuddied z3fold page, create new one */
|
||||
page = alloc_page(gfp);
|
||||
if (!page)
|
||||
return -ENOMEM;
|
||||
spin_lock(&pool->lock);
|
||||
|
||||
atomic64_inc(&pool->pages_nr);
|
||||
zhdr = init_z3fold_page(page);
|
||||
|
||||
if (bud == HEADLESS) {
|
||||
set_bit(PAGE_HEADLESS, &page->private);
|
||||
spin_lock(&pool->lock);
|
||||
goto headless;
|
||||
}
|
||||
z3fold_page_lock(zhdr);
|
||||
|
||||
found:
|
||||
if (bud == FIRST)
|
||||
@ -406,6 +432,7 @@ found:
|
||||
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
|
||||
}
|
||||
|
||||
spin_lock(&pool->lock);
|
||||
if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
|
||||
zhdr->middle_chunks == 0) {
|
||||
/* Add to unbuddied list */
|
||||
@ -425,6 +452,8 @@ headless:
|
||||
|
||||
*handle = encode_handle(zhdr, bud);
|
||||
spin_unlock(&pool->lock);
|
||||
if (bud != HEADLESS)
|
||||
z3fold_page_unlock(zhdr);
|
||||
|
||||
return 0;
|
||||
}
|
||||
@ -446,7 +475,6 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
|
||||
struct page *page;
|
||||
enum buddy bud;
|
||||
|
||||
spin_lock(&pool->lock);
|
||||
zhdr = handle_to_z3fold_header(handle);
|
||||
page = virt_to_page(zhdr);
|
||||
|
||||
@ -454,6 +482,7 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
|
||||
/* HEADLESS page stored */
|
||||
bud = HEADLESS;
|
||||
} else {
|
||||
z3fold_page_lock(zhdr);
|
||||
bud = handle_to_buddy(handle);
|
||||
|
||||
switch (bud) {
|
||||
@ -470,37 +499,59 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
|
||||
default:
|
||||
pr_err("%s: unknown bud %d\n", __func__, bud);
|
||||
WARN_ON(1);
|
||||
spin_unlock(&pool->lock);
|
||||
z3fold_page_unlock(zhdr);
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
if (test_bit(UNDER_RECLAIM, &page->private)) {
|
||||
/* z3fold page is under reclaim, reclaim will free */
|
||||
spin_unlock(&pool->lock);
|
||||
if (bud != HEADLESS)
|
||||
z3fold_page_unlock(zhdr);
|
||||
return;
|
||||
}
|
||||
|
||||
/* Remove from existing buddy list */
|
||||
if (bud != HEADLESS)
|
||||
list_del(&zhdr->buddy);
|
||||
if (bud != HEADLESS) {
|
||||
spin_lock(&pool->lock);
|
||||
/*
|
||||
* this object may have been removed from its list by
|
||||
* z3fold_alloc(). In that case we just do nothing,
|
||||
* z3fold_alloc() will allocate an object and add the page
|
||||
* to the relevant list.
|
||||
*/
|
||||
if (!list_empty(&zhdr->buddy)) {
|
||||
list_del(&zhdr->buddy);
|
||||
} else {
|
||||
spin_unlock(&pool->lock);
|
||||
z3fold_page_unlock(zhdr);
|
||||
return;
|
||||
}
|
||||
spin_unlock(&pool->lock);
|
||||
}
|
||||
|
||||
if (bud == HEADLESS ||
|
||||
(zhdr->first_chunks == 0 && zhdr->middle_chunks == 0 &&
|
||||
zhdr->last_chunks == 0)) {
|
||||
/* z3fold page is empty, free */
|
||||
spin_lock(&pool->lock);
|
||||
list_del(&page->lru);
|
||||
spin_unlock(&pool->lock);
|
||||
clear_bit(PAGE_HEADLESS, &page->private);
|
||||
if (bud != HEADLESS)
|
||||
z3fold_page_unlock(zhdr);
|
||||
free_z3fold_page(zhdr);
|
||||
atomic64_dec(&pool->pages_nr);
|
||||
} else {
|
||||
z3fold_compact_page(zhdr);
|
||||
/* Add to the unbuddied list */
|
||||
spin_lock(&pool->lock);
|
||||
freechunks = num_free_chunks(zhdr);
|
||||
list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
|
||||
spin_unlock(&pool->lock);
|
||||
z3fold_page_unlock(zhdr);
|
||||
}
|
||||
|
||||
spin_unlock(&pool->lock);
|
||||
}
|
||||
|
||||
/**
|
||||
@ -547,12 +598,15 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
|
||||
unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
|
||||
|
||||
spin_lock(&pool->lock);
|
||||
if (!pool->ops || !pool->ops->evict || list_empty(&pool->lru) ||
|
||||
retries == 0) {
|
||||
if (!pool->ops || !pool->ops->evict || retries == 0) {
|
||||
spin_unlock(&pool->lock);
|
||||
return -EINVAL;
|
||||
}
|
||||
for (i = 0; i < retries; i++) {
|
||||
if (list_empty(&pool->lru)) {
|
||||
spin_unlock(&pool->lock);
|
||||
return -EINVAL;
|
||||
}
|
||||
page = list_last_entry(&pool->lru, struct page, lru);
|
||||
list_del(&page->lru);
|
||||
|
||||
@ -561,6 +615,8 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
|
||||
zhdr = page_address(page);
|
||||
if (!test_bit(PAGE_HEADLESS, &page->private)) {
|
||||
list_del(&zhdr->buddy);
|
||||
spin_unlock(&pool->lock);
|
||||
z3fold_page_lock(zhdr);
|
||||
/*
|
||||
* We need encode the handles before unlocking, since
|
||||
* we can race with free that will set
|
||||
@ -575,13 +631,13 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
|
||||
middle_handle = encode_handle(zhdr, MIDDLE);
|
||||
if (zhdr->last_chunks)
|
||||
last_handle = encode_handle(zhdr, LAST);
|
||||
z3fold_page_unlock(zhdr);
|
||||
} else {
|
||||
first_handle = encode_handle(zhdr, HEADLESS);
|
||||
last_handle = middle_handle = 0;
|
||||
spin_unlock(&pool->lock);
|
||||
}
|
||||
|
||||
spin_unlock(&pool->lock);
|
||||
|
||||
/* Issue the eviction callback(s) */
|
||||
if (middle_handle) {
|
||||
ret = pool->ops->evict(pool, middle_handle);
|
||||
@ -599,7 +655,8 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
|
||||
goto next;
|
||||
}
|
||||
next:
|
||||
spin_lock(&pool->lock);
|
||||
if (!test_bit(PAGE_HEADLESS, &page->private))
|
||||
z3fold_page_lock(zhdr);
|
||||
clear_bit(UNDER_RECLAIM, &page->private);
|
||||
if ((test_bit(PAGE_HEADLESS, &page->private) && ret == 0) ||
|
||||
(zhdr->first_chunks == 0 && zhdr->last_chunks == 0 &&
|
||||
@ -608,26 +665,34 @@ next:
|
||||
* All buddies are now free, free the z3fold page and
|
||||
* return success.
|
||||
*/
|
||||
clear_bit(PAGE_HEADLESS, &page->private);
|
||||
if (!test_and_clear_bit(PAGE_HEADLESS, &page->private))
|
||||
z3fold_page_unlock(zhdr);
|
||||
free_z3fold_page(zhdr);
|
||||
atomic64_dec(&pool->pages_nr);
|
||||
spin_unlock(&pool->lock);
|
||||
return 0;
|
||||
} else if (!test_bit(PAGE_HEADLESS, &page->private)) {
|
||||
if (zhdr->first_chunks != 0 &&
|
||||
zhdr->last_chunks != 0 &&
|
||||
zhdr->middle_chunks != 0) {
|
||||
/* Full, add to buddied list */
|
||||
spin_lock(&pool->lock);
|
||||
list_add(&zhdr->buddy, &pool->buddied);
|
||||
spin_unlock(&pool->lock);
|
||||
} else {
|
||||
z3fold_compact_page(zhdr);
|
||||
/* add to unbuddied list */
|
||||
spin_lock(&pool->lock);
|
||||
freechunks = num_free_chunks(zhdr);
|
||||
list_add(&zhdr->buddy,
|
||||
&pool->unbuddied[freechunks]);
|
||||
spin_unlock(&pool->lock);
|
||||
}
|
||||
}
|
||||
|
||||
if (!test_bit(PAGE_HEADLESS, &page->private))
|
||||
z3fold_page_unlock(zhdr);
|
||||
|
||||
spin_lock(&pool->lock);
|
||||
/* add to beginning of LRU */
|
||||
list_add(&page->lru, &pool->lru);
|
||||
}
|
||||
@ -652,7 +717,6 @@ static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
|
||||
void *addr;
|
||||
enum buddy buddy;
|
||||
|
||||
spin_lock(&pool->lock);
|
||||
zhdr = handle_to_z3fold_header(handle);
|
||||
addr = zhdr;
|
||||
page = virt_to_page(zhdr);
|
||||
@ -660,6 +724,7 @@ static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
|
||||
if (test_bit(PAGE_HEADLESS, &page->private))
|
||||
goto out;
|
||||
|
||||
z3fold_page_lock(zhdr);
|
||||
buddy = handle_to_buddy(handle);
|
||||
switch (buddy) {
|
||||
case FIRST:
|
||||
@ -678,8 +743,9 @@ static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
|
||||
addr = NULL;
|
||||
break;
|
||||
}
|
||||
|
||||
z3fold_page_unlock(zhdr);
|
||||
out:
|
||||
spin_unlock(&pool->lock);
|
||||
return addr;
|
||||
}
|
||||
|
||||
@ -694,19 +760,17 @@ static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
|
||||
struct page *page;
|
||||
enum buddy buddy;
|
||||
|
||||
spin_lock(&pool->lock);
|
||||
zhdr = handle_to_z3fold_header(handle);
|
||||
page = virt_to_page(zhdr);
|
||||
|
||||
if (test_bit(PAGE_HEADLESS, &page->private)) {
|
||||
spin_unlock(&pool->lock);
|
||||
if (test_bit(PAGE_HEADLESS, &page->private))
|
||||
return;
|
||||
}
|
||||
|
||||
z3fold_page_lock(zhdr);
|
||||
buddy = handle_to_buddy(handle);
|
||||
if (buddy == MIDDLE)
|
||||
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
|
||||
spin_unlock(&pool->lock);
|
||||
z3fold_page_unlock(zhdr);
|
||||
}
|
||||
|
||||
/**
|
||||
|
Loading…
Reference in New Issue
Block a user