forked from Minki/linux
Change dmapool free block management
Use a list of free blocks within a page instead of using a bitmap. Update documentation to reflect this. As well as being a slight reduction in memory allocation, locked ops and lines of code, it speeds up a transaction processing benchmark by 0.4%. Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
This commit is contained in:
Matthew Wilcox
parent
6182a0943a
commit
a35a345514
119
mm/dmapool.c
119
mm/dmapool.c
@ -17,7 +17,9 @@
|
||||
* The current design of this allocator is fairly simple. The pool is
|
||||
* represented by the 'struct dma_pool' which keeps a doubly-linked list of
|
||||
* allocated pages. Each page in the page_list is split into blocks of at
|
||||
* least 'size' bytes.
|
||||
* least 'size' bytes. Free blocks are tracked in an unsorted singly-linked
|
||||
* list of free blocks within the page. Used blocks aren't tracked, but we
|
||||
* keep a count of how many are currently allocated from each page.
|
||||
*/
|
||||
|
||||
#include <linux/device.h>
|
||||
@ -38,7 +40,6 @@
|
||||
struct dma_pool { /* the pool */
|
||||
struct list_head page_list;
|
||||
spinlock_t lock;
|
||||
size_t blocks_per_page;
|
||||
size_t size;
|
||||
struct device *dev;
|
||||
size_t allocation;
|
||||
@ -51,8 +52,8 @@ struct dma_page { /* cacheable header for 'allocation' bytes */
|
||||
struct list_head page_list;
|
||||
void *vaddr;
|
||||
dma_addr_t dma;
|
||||
unsigned in_use;
|
||||
unsigned long bitmap[0];
|
||||
unsigned int in_use;
|
||||
unsigned int offset;
|
||||
};
|
||||
|
||||
#define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000)
|
||||
@ -87,8 +88,8 @@ show_pools(struct device *dev, struct device_attribute *attr, char *buf)
|
||||
|
||||
/* per-pool info, no real statistics yet */
|
||||
temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
|
||||
pool->name,
|
||||
blocks, pages * pool->blocks_per_page,
|
||||
pool->name, blocks,
|
||||
pages * (pool->allocation / pool->size),
|
||||
pool->size, pages);
|
||||
size -= temp;
|
||||
next += temp;
|
||||
@ -132,8 +133,11 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
|
||||
return NULL;
|
||||
}
|
||||
|
||||
if (size == 0)
|
||||
if (size == 0) {
|
||||
return NULL;
|
||||
} else if (size < 4) {
|
||||
size = 4;
|
||||
}
|
||||
|
||||
if ((size % align) != 0)
|
||||
size = ALIGN(size, align);
|
||||
@ -160,7 +164,6 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
|
||||
spin_lock_init(&retval->lock);
|
||||
retval->size = size;
|
||||
retval->allocation = allocation;
|
||||
retval->blocks_per_page = allocation / size;
|
||||
init_waitqueue_head(&retval->waitq);
|
||||
|
||||
if (dev) {
|
||||
@ -186,28 +189,36 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
|
||||
}
|
||||
EXPORT_SYMBOL(dma_pool_create);
|
||||
|
||||
static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
|
||||
{
|
||||
unsigned int offset = 0;
|
||||
|
||||
do {
|
||||
unsigned int next = offset + pool->size;
|
||||
if (unlikely((next + pool->size) >= pool->allocation))
|
||||
next = pool->allocation;
|
||||
*(int *)(page->vaddr + offset) = next;
|
||||
offset = next;
|
||||
} while (offset < pool->allocation);
|
||||
}
|
||||
|
||||
static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
|
||||
{
|
||||
struct dma_page *page;
|
||||
int mapsize;
|
||||
|
||||
mapsize = pool->blocks_per_page;
|
||||
mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
|
||||
mapsize *= sizeof(long);
|
||||
|
||||
page = kmalloc(mapsize + sizeof *page, mem_flags);
|
||||
page = kmalloc(sizeof(*page), mem_flags);
|
||||
if (!page)
|
||||
return NULL;
|
||||
page->vaddr = dma_alloc_coherent(pool->dev,
|
||||
pool->allocation,
|
||||
page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
|
||||
&page->dma, mem_flags);
|
||||
if (page->vaddr) {
|
||||
memset(page->bitmap, 0xff, mapsize); /* bit set == free */
|
||||
#ifdef CONFIG_DEBUG_SLAB
|
||||
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
|
||||
#endif
|
||||
pool_initialise_page(pool, page);
|
||||
list_add(&page->page_list, &pool->page_list);
|
||||
page->in_use = 0;
|
||||
page->offset = 0;
|
||||
} else {
|
||||
kfree(page);
|
||||
page = NULL;
|
||||
@ -215,14 +226,9 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
|
||||
return page;
|
||||
}
|
||||
|
||||
static inline int is_page_busy(int blocks, unsigned long *bitmap)
|
||||
static inline int is_page_busy(struct dma_page *page)
|
||||
{
|
||||
while (blocks > 0) {
|
||||
if (*bitmap++ != ~0UL)
|
||||
return 1;
|
||||
blocks -= BITS_PER_LONG;
|
||||
}
|
||||
return 0;
|
||||
return page->in_use != 0;
|
||||
}
|
||||
|
||||
static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
|
||||
@ -257,7 +263,7 @@ void dma_pool_destroy(struct dma_pool *pool)
|
||||
struct dma_page *page;
|
||||
page = list_entry(pool->page_list.next,
|
||||
struct dma_page, page_list);
|
||||
if (is_page_busy(pool->blocks_per_page, page->bitmap)) {
|
||||
if (is_page_busy(page)) {
|
||||
if (pool->dev)
|
||||
dev_err(pool->dev,
|
||||
"dma_pool_destroy %s, %p busy\n",
|
||||
@ -292,27 +298,14 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
|
||||
{
|
||||
unsigned long flags;
|
||||
struct dma_page *page;
|
||||
int map, block;
|
||||
size_t offset;
|
||||
void *retval;
|
||||
|
||||
spin_lock_irqsave(&pool->lock, flags);
|
||||
restart:
|
||||
list_for_each_entry(page, &pool->page_list, page_list) {
|
||||
int i;
|
||||
/* only cachable accesses here ... */
|
||||
for (map = 0, i = 0;
|
||||
i < pool->blocks_per_page; i += BITS_PER_LONG, map++) {
|
||||
if (page->bitmap[map] == 0)
|
||||
continue;
|
||||
block = ffz(~page->bitmap[map]);
|
||||
if ((i + block) < pool->blocks_per_page) {
|
||||
clear_bit(block, &page->bitmap[map]);
|
||||
offset = (BITS_PER_LONG * map) + block;
|
||||
offset *= pool->size;
|
||||
goto ready;
|
||||
}
|
||||
}
|
||||
if (page->offset < pool->allocation)
|
||||
goto ready;
|
||||
}
|
||||
page = pool_alloc_page(pool, GFP_ATOMIC);
|
||||
if (!page) {
|
||||
@ -333,10 +326,10 @@ void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
|
||||
goto done;
|
||||
}
|
||||
|
||||
clear_bit(0, &page->bitmap[0]);
|
||||
offset = 0;
|
||||
ready:
|
||||
page->in_use++;
|
||||
offset = page->offset;
|
||||
page->offset = *(int *)(page->vaddr + offset);
|
||||
retval = offset + page->vaddr;
|
||||
*handle = offset + page->dma;
|
||||
#ifdef CONFIG_DEBUG_SLAB
|
||||
@ -379,7 +372,7 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
|
||||
{
|
||||
struct dma_page *page;
|
||||
unsigned long flags;
|
||||
int map, block;
|
||||
unsigned int offset;
|
||||
|
||||
page = pool_find_page(pool, dma);
|
||||
if (!page) {
|
||||
@ -393,13 +386,9 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
|
||||
return;
|
||||
}
|
||||
|
||||
block = dma - page->dma;
|
||||
block /= pool->size;
|
||||
map = block / BITS_PER_LONG;
|
||||
block %= BITS_PER_LONG;
|
||||
|
||||
offset = vaddr - page->vaddr;
|
||||
#ifdef CONFIG_DEBUG_SLAB
|
||||
if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
|
||||
if ((dma - page->dma) != offset) {
|
||||
if (pool->dev)
|
||||
dev_err(pool->dev,
|
||||
"dma_pool_free %s, %p (bad vaddr)/%Lx\n",
|
||||
@ -410,28 +399,36 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
|
||||
pool->name, vaddr, (unsigned long long)dma);
|
||||
return;
|
||||
}
|
||||
if (page->bitmap[map] & (1UL << block)) {
|
||||
if (pool->dev)
|
||||
dev_err(pool->dev,
|
||||
"dma_pool_free %s, dma %Lx already free\n",
|
||||
pool->name, (unsigned long long)dma);
|
||||
else
|
||||
printk(KERN_ERR
|
||||
"dma_pool_free %s, dma %Lx already free\n",
|
||||
pool->name, (unsigned long long)dma);
|
||||
return;
|
||||
{
|
||||
unsigned int chain = page->offset;
|
||||
while (chain < pool->allocation) {
|
||||
if (chain != offset) {
|
||||
chain = *(int *)(page->vaddr + chain);
|
||||
continue;
|
||||
}
|
||||
if (pool->dev)
|
||||
dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
|
||||
"already free\n", pool->name,
|
||||
(unsigned long long)dma);
|
||||
else
|
||||
printk(KERN_ERR "dma_pool_free %s, dma %Lx "
|
||||
"already free\n", pool->name,
|
||||
(unsigned long long)dma);
|
||||
return;
|
||||
}
|
||||
}
|
||||
memset(vaddr, POOL_POISON_FREED, pool->size);
|
||||
#endif
|
||||
|
||||
spin_lock_irqsave(&pool->lock, flags);
|
||||
page->in_use--;
|
||||
set_bit(block, &page->bitmap[map]);
|
||||
*(int *)vaddr = page->offset;
|
||||
page->offset = offset;
|
||||
if (waitqueue_active(&pool->waitq))
|
||||
wake_up_locked(&pool->waitq);
|
||||
/*
|
||||
* Resist a temptation to do
|
||||
* if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
|
||||
* if (!is_page_busy(page)) pool_free_page(pool, page);
|
||||
* Better have a few empty pages hang around.
|
||||
*/
|
||||
spin_unlock_irqrestore(&pool->lock, flags);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user