void *slob_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
{
void *b;
flags &= gfp_allowed_mask;
lockdep_trace_alloc(flags);
if (c->size < PAGE_SIZE) {
b = slob_alloc(c->size, flags, c->align, node);
trace_kmem_cache_alloc_node(_RET_IP_, b, c->object_size,
SLOB_UNITS(c->size) * SLOB_UNIT,
flags, node);
} else {
b = slob_new_pages(flags, get_order(c->size), node);
trace_kmem_cache_alloc_node(_RET_IP_, b, c->object_size,
PAGE_SIZE << get_order(c->size),
flags, node);
}
if (b && c->ctor)
c->ctor(b);
kmemleak_alloc_recursive(b, c->size, 1, c->flags, flags);
return b;
}
/*synarthsh opoy elegxoyme ean se mia page yparxei kapoio block poy na xoraei to request mas*/
int check_block(struct slob_page *sp, size_t size, int align){
slob_t *prev, *cur, *aligned = NULL;
int delta = 0, units = SLOB_UNITS(size);
slobidx_t avail ;
/*diatrexoyme thn lista mexri na broyme kapoio block opoy xoraei to request*/
for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
avail = slob_units(cur);
if (align) {
aligned = (slob_t *)ALIGN((unsigned long)cur, align);
delta = aligned - cur;
}
if (avail >= units + delta) { /* room enough? */
return(1);
}
/*an einai to teleytaio sth lista bgainei apo thn for */
if(slob_last(cur)){
break;
}
}
return(0);
}
/*
* slob_alloc: entry point into the slob allocator.
*
* We modified the slob_alloc function. We defined new local variables:
* 1.) temp_amt_free will accumulate all the free bytes on each page
* (used for the system call sys_get_slob_amt_free);
* 2.) best_sp points to the page with the "best fit";
* 3.) best_fit/ current_fit contain a number in which the smaller
* the number, the better the fit; best_fit is the overall best number
* and current_fit is the current page's number
*
* When iterating through the free page list, our slob_alloc will:
* 1.) collect the free units of the page and store them into
* temp_amt_free;
* 2.) call a helper function slob_page_best_fit_check which
* returns a number put into current_fit.
* 3.) This current_fit number is checked against a number of
* cases. First case is if current_fit is equal to 0. This means,
* a perfect fit, so we break out of the loop and allocate there.
* Second case is -1, meaning there is no block fit so we continue
* the loop. Last case is some positive number so we check to see if
* this number is less than the best_fit. Or we check to see if
* best_fit has been set yet. If this case is reached, then the new
* best page is the current page in the loop.
*
* Once the loop is over, we try to allocate on that page if best_fit is
* some positive number. Otherwise, we don't have enough space and must
* allocate a new page. This part of the slob_alloc function was mostly
* unchanged except for updating the values of the array lists for the
* system calls. When we have to allocate a new page, is when we set the
* amt_claimed, at position of the counter, to the size of the request (in
* bytes). We also set the amt_free, at the position of the counter, to
* the total accumulated units from the list, converting it to bytes. Then
* we increment the counter.
*
*/
static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
{
struct slob_page *sp;
struct list_head *prev;
struct list_head *slob_list;
slob_t *b = NULL;
unsigned long flags;
// Lab 3 - Statistics
long temp_amt_free = 0;
struct slob_page *best_sp = NULL;
int best_fit = -1;
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
spin_lock_irqsave(&slob_lock, flags);
/* Iterate through each partially free page, try to find room */
list_for_each_entry(sp, slob_list, list) {
int current_fit = -1;
// Lab 3 - Statistics
temp_amt_free = temp_amt_free + sp->units;
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
* page with a matching node id in the freelist.
*/
if (node != -1 && page_to_nid(&sp->page) != node)
continue;
#endif
/* Enough room on this page? */
if (sp->units < SLOB_UNITS(size))
continue;
#ifdef SLOB_BEST_FIT_ALG
current_fit = slob_page_best_fit_check(sp, size, align);
if(current_fit == 0) {
best_sp = sp;
best_fit = current_fit;
break;
}
else if(current_fit > 0 && (best_fit == -1 || current_fit < best_fit) ) {
best_sp = sp;
best_fit = current_fit;
}
continue;
}
/*
* Allocate a slob block within a given slob_page sp.
*/
static void *slob_page_alloc(struct page *sp, size_t size, int align)
{
slob_t *prev, *cur, *aligned = NULL;
int delta = 0, units = SLOB_UNITS(size);
for (prev = NULL, cur = sp->freelist; ; prev = cur, cur = slob_next(cur)) {
slobidx_t avail = slob_units(cur);
if (align) {
aligned = (slob_t *)ALIGN((unsigned long)cur, align);
delta = aligned - cur;
}
if (avail >= units + delta) { /* room enough? */
slob_t *next;
if (delta) { /* need to fragment head to align? */
next = slob_next(cur);
set_slob(aligned, avail - delta, next);
set_slob(cur, delta, aligned);
prev = cur;
cur = aligned;
avail = slob_units(cur);
}
next = slob_next(cur);
if (avail == units) { /* exact fit? unlink. */
if (prev)
set_slob(prev, slob_units(prev), next);
else
sp->freelist = next;
} else { /* fragment */
if (prev)
set_slob(prev, slob_units(prev), cur + units);
else
sp->freelist = cur + units;
set_slob(cur + units, avail - units, next);
}
sp->units -= units;
if (!sp->units)
clear_slob_page_free(sp);
return cur;
}
if (slob_last(cur))
return NULL;
}
}
/* can't use ksize for kmem_cache_alloc memory, only kmalloc */
size_t ksize(const void *block)
{
struct page *sp;
int align;
unsigned int *m;
BUG_ON(!block);
if (unlikely(block == ZERO_SIZE_PTR))
return 0;
sp = virt_to_page(block);
if (unlikely(!PageSlab(sp)))
return PAGE_SIZE << compound_order(sp);
align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
m = (unsigned int *)(block - align);
return SLOB_UNITS(*m) * SLOB_UNIT;
}
asmlinkage long sys_slob_claimed(void)
{
long slob_total = SLOB_UNITS(PAGE_SIZE) * slob_page_count;
return slob_total;
}
/*
* slob_alloc: entry point into the slob allocator.
*/
static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
{
struct slob_page *sp = NULL;
struct slob_page *sp_t;
struct list_head *slob_list;
slob_t *b = NULL;
unsigned long flags;
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
spin_lock_irqsave(&slob_lock, flags);
/* Iterate through each partially free page, try to find room */
list_for_each_entry(sp_t, slob_list, list) {
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
* page with a matching node id in the freelist.
*/
if (node != -1 && page_to_nid(&sp_t->page) != node)
continue;
#endif
/* Enough room on this page? */
if (sp_t->units < SLOB_UNITS(size))
/* Not enough room */
continue;
if (sp == NULL)
sp = sp_t;
if (sp_t->units < sp->units)
/* Get the smallest slob_page that
* is large enough for our needs */
sp = sp_t;
}
/* Attempt to alloc */
if(sp != NULL) {
b = slob_page_alloc(sp, size, align);
}
spin_unlock_irqrestore(&slob_lock, flags);
/* Not enough space: must allocate a new page */
if (!b) {
b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node);
if (!b)
return NULL;
sp = slob_page(b);
set_slob_page(sp);
/* We allocatted a new page, increment the count */
slob_page_count++;
spin_lock_irqsave(&slob_lock, flags);
sp->units = SLOB_UNITS(PAGE_SIZE);
sp->free = b;
INIT_LIST_HEAD(&sp->list);
set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
set_slob_page_free(sp, slob_list);
b = slob_page_alloc(sp, size, align);
BUG_ON(!b);
spin_unlock_irqrestore(&slob_lock, flags);
}
if (unlikely((gfp & __GFP_ZERO) && b))
memset(b, 0, size);
return b;
}
/*
* slob_alloc: entry point into the slob allocator.
*/
static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
{
struct slob_page *sp;
struct list_head *slob_list;
slob_t *b = NULL;
unsigned long flags;
int i;
unsigned long int count_free;
#ifdef BESTFIT_PAGE
slobidx_t min,prev_min;
struct slob_page *curr;
int flag_if;
int check;
#else
struct list_head *prev;
#endif
/*arxikopoioyme ta total_alloc kai ta total_free*/
if(flag_mem==0){
total_alloc = 0;
total_free = 0;
flag_mem = 1;
}
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
spin_lock_irqsave(&slob_lock, flags);
/* Iterate through each partially free page, try to find room */
counter_print++;
#ifdef BESTFIT_PAGE
flag_if = 0;
curr = NULL;
min = 0;
prev_min = SLOB_UNITS(size);
/*diatexoume th lista mexri na broyme thn kalyterh selida*/
list_for_each_entry(sp, slob_list, list) {
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
* page with a matching node id in the freelist.
*/
if (node != -1 && page_to_nid(&sp->page) != node)
continue;
#endif
/* Enough room on this page? */
if (sp->units < prev_min){
continue;
}
if(flag_if==0){
check = check_block(sp,size,align);
if(check){
min = sp->units;
curr = sp;
flag_if = 1;
}
}
else{
if(sp->units <= min){
check = check_block(sp,size,align);
if(check){
min = sp->units;
curr = sp;
}
}
}
}
//kaloyme thn slob_page_alloc
if(curr!=NULL){
b = slob_page_alloc(curr, size, align);
}
else{
b = NULL;
}
#else
list_for_each_entry(sp, slob_list, list) {
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
* page with a matching node id in the freelist.
*/
if (node != -1 && page_to_nid(&sp->page) != node)
continue;
#endif
/* Enough room on this page? */
if (sp->units < SLOB_UNITS(size))
continue;
/* Attempt to alloc */
prev = sp->list.prev;
b = slob_page_alloc(sp, size, align);
if (!b)
continue;
/* Improve fragment distribution and reduce our average
* search time by starting our next search here. (see
* Knuth vol 1, sec 2.5, pg 449) */
if (prev != slob_list->prev &&
slob_list->next != prev->next)
list_move_tail(slob_list, prev->next);
break;
}
#endif
spin_unlock_irqrestore(&slob_lock, flags);
/* Not enough space: must allocate a new page */
if (!b) {
b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node);
if (!b)
return NULL;
sp = slob_page(b);
set_slob_page(sp);
spin_lock_irqsave(&slob_lock, flags);
sp->units = SLOB_UNITS(PAGE_SIZE);
sp->free = b;
INIT_LIST_HEAD(&sp->list);
set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
set_slob_page_free(sp, slob_list);
b = slob_page_alloc(sp, size, align);
BUG_ON(!b);
spin_unlock_irqrestore(&slob_lock, flags);
}
if (unlikely((gfp & __GFP_ZERO) && b))
memset(b, 0, size);
/*diatrexoyme kai tis treis listes megethon gia na metrhsoyme ta synolika free olwn twn selidwn*/
count_free = 0;
for(i=0;i<3;i++){
if (i==0){
slob_list = &free_slob_small;
}
else if (i==1){
slob_list = &free_slob_medium;
}
else{
slob_list = &free_slob_large;
}
list_for_each_entry(sp, slob_list, list) {
count_free = count_free + sp->units;
}
}
/*
* Allocate a slob block within a given slob_page sp.
*/
static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
{
slob_t *prev, *cur, *aligned = NULL;
int delta = 0, units = SLOB_UNITS(size);
#ifdef BESTFIT_BLOCK
slob_t *min_cur = NULL,*min_aligned = NULL,*min_prev;
slobidx_t min_avail = 0;
int flag_if = 0 ,min_delta = 0;
slobidx_t avail ;
#endif
#ifdef BESTFIT_BLOCK
if((counter_print%print_iteration) == 0){
printk("\nslob_Request: %d\n",units);
printk("slob_alloc: Candidate blocks size:");
}
/*diatrexoyme thn lista mexri na broyme to best block*/
for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
avail = slob_units(cur);
if((counter_print%print_iteration) == 0){
printk(" %d",avail);
}
if (align) {
aligned = (slob_t *)ALIGN((unsigned long)cur, align);
delta = aligned - cur;
}
if (avail >= units + delta) { /* room enough? */
/*arxikopoioyme ta min*/
if(!flag_if){
min_avail = slob_units(cur);
min_cur = cur;
min_aligned = aligned;
min_delta = delta;
min_prev = prev;
flag_if = 1;
}
else {
/*se periptosh poy brethei kalytero block tote allazoyme tis thmes twn min*/
if(min_avail > avail){
min_avail = avail;
min_cur = cur;
min_aligned = aligned;
min_delta = delta;
min_prev = prev;
}
}
}
/*an einai to teleytaio sth lista bgainei apo thn for */
if(slob_last(cur)){
break;
}
}
/*an exei brethei block poy na xoraei to request tote to epilegoume*/
if(min_avail!=0){
slob_t *next;
cur = min_cur;
avail = min_avail;
delta = min_delta;
aligned = min_aligned;
prev = min_prev;
if (delta) { /* need to fragment head to align? */
next = slob_next(cur);
set_slob(aligned, avail - delta, next);
set_slob(cur, delta, aligned);
prev = cur;
cur = aligned;
avail = slob_units(cur);
}
next = slob_next(cur);
if (avail == units) { /* exact fit? unlink. */
if (prev)
set_slob(prev, slob_units(prev), next);
else
sp->free = next;
}
else { /* fragment */
if (prev)
set_slob(prev, slob_units(prev), cur + units);
else
sp->free = cur + units;
set_slob(cur + units, avail - units, next);
}
sp->units -= units;
if (!sp->units)
clear_slob_page_free(sp);
if((counter_print%print_iteration) == 0){
printk("\nslob_alloc: Best Fit: %d\n",min_avail);
}
return cur;
}
else{
if((counter_print%print_iteration) == 0){
printk("\nslob_alloc: Best Fit: None\n");
}
return NULL;
}
#else
if((counter_print%print_iteration) == 0){
printk("\nslob_Request: %d\n",units);
printk("slob_alloc: Candidate blocks size:");
}
for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
slobidx_t avail = slob_units(cur);
if((counter_print%print_iteration) == 0){
printk(" %d",avail);
}
if (align) {
aligned = (slob_t *)ALIGN((unsigned long)cur, align);
delta = aligned - cur;
}
if (avail >= units + delta) { /* room enough? */
slob_t *next;
if (delta) { /* need to fragment head to align? */
next = slob_next(cur);
set_slob(aligned, avail - delta, next);
set_slob(cur, delta, aligned);
prev = cur;
cur = aligned;
avail = slob_units(cur);
}
next = slob_next(cur);
if (avail == units) { /* exact fit? unlink. */
if (prev)
set_slob(prev, slob_units(prev), next);
else
sp->free = next;
}
else { /* fragment */
if (prev)
set_slob(prev, slob_units(prev), cur + units);
else
sp->free = cur + units;
set_slob(cur + units, avail - units, next);
}
sp->units -= units;
if (!sp->units)
clear_slob_page_free(sp);
if((counter_print%print_iteration) == 0){
printk("\nslob_alloc: First Fit is the last available\n");
}
return cur;
}
if (slob_last(cur)){
if((counter_print%print_iteration) == 0){
printk("\nslob_alloc: First Fit: None\n");
}
return NULL;
}
}
#endif
}
/*
* slob_free: entry point into the slob allocator.
*/
static void slob_free(void *block, int size)
{
struct page *sp;
slob_t *prev, *next, *b = (slob_t *)block;
slobidx_t units;
unsigned long flags;
struct list_head *slob_list;
if (unlikely(ZERO_OR_NULL_PTR(block)))
return;
BUG_ON(!size);
sp = virt_to_page(block);
units = SLOB_UNITS(size);
spin_lock_irqsave(&slob_lock, flags);
if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) {
/* Go directly to page allocator. Do not pass slob allocator */
if (slob_page_free(sp))
clear_slob_page_free(sp);
spin_unlock_irqrestore(&slob_lock, flags);
__ClearPageSlab(sp);
page_mapcount_reset(sp);
slob_free_pages(b, 0);
return;
}
if (!slob_page_free(sp)) {
/* This slob page is about to become partially free. Easy! */
sp->units = units;
sp->freelist = b;
set_slob(b, units,
(void *)((unsigned long)(b +
SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK));
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
set_slob_page_free(sp, slob_list);
goto out;
}
/*
* Otherwise the page is already partially free, so find reinsertion
* point.
*/
sp->units += units;
if (b < (slob_t *)sp->freelist) {
if (b + units == sp->freelist) {
units += slob_units(sp->freelist);
sp->freelist = slob_next(sp->freelist);
}
set_slob(b, units, sp->freelist);
sp->freelist = b;
} else {
prev = sp->freelist;
next = slob_next(prev);
while (b > next) {
prev = next;
next = slob_next(prev);
}
if (!slob_last(prev) && b + units == next) {
units += slob_units(next);
set_slob(b, units, slob_next(next));
} else
set_slob(b, units, next);
if (prev + slob_units(prev) == b) {
units = slob_units(b) + slob_units(prev);
set_slob(prev, units, slob_next(b));
} else
set_slob(prev, slob_units(prev), b);
}
out:
spin_unlock_irqrestore(&slob_lock, flags);
}
/*
* slob_alloc: entry point into the slob allocator.
*/
static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
{
struct page *sp;
struct list_head *prev;
struct list_head *slob_list;
slob_t *b = NULL;
unsigned long flags;
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
spin_lock_irqsave(&slob_lock, flags);
/* Iterate through each partially free page, try to find room */
list_for_each_entry(sp, slob_list, lru) {
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
* page with a matching node id in the freelist.
*/
if (node != NUMA_NO_NODE && page_to_nid(sp) != node)
continue;
#endif
/* Enough room on this page? */
if (sp->units < SLOB_UNITS(size))
continue;
/* Attempt to alloc */
prev = sp->lru.prev;
b = slob_page_alloc(sp, size, align);
if (!b)
continue;
/* Improve fragment distribution and reduce our average
* search time by starting our next search here. (see
* Knuth vol 1, sec 2.5, pg 449) */
if (prev != slob_list->prev &&
slob_list->next != prev->next)
list_move_tail(slob_list, prev->next);
break;
}
spin_unlock_irqrestore(&slob_lock, flags);
/* Not enough space: must allocate a new page */
if (!b) {
b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node);
if (!b)
return NULL;
sp = virt_to_page(b);
__SetPageSlab(sp);
spin_lock_irqsave(&slob_lock, flags);
sp->units = SLOB_UNITS(PAGE_SIZE);
sp->freelist = b;
INIT_LIST_HEAD(&sp->lru);
set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
set_slob_page_free(sp, slob_list);
b = slob_page_alloc(sp, size, align);
BUG_ON(!b);
spin_unlock_irqrestore(&slob_lock, flags);
}
if (unlikely((gfp & __GFP_ZERO) && b))
memset(b, 0, size);
return b;
}
static void slob_free(void *block, int size)
{
struct page *sp;
slob_t *prev, *next, *b = (slob_t *)block;
slobidx_t units;
unsigned long flags;
struct list_head *slob_list;
if (unlikely(ZERO_OR_NULL_PTR(block)))
return;
BUG_ON(!size);
sp = slob_page(block);
units = SLOB_UNITS(size);
spin_lock_irqsave(&slob_lock, flags);
if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) {
if (slob_page_free(sp))
clear_slob_page_free(sp);
spin_unlock_irqrestore(&slob_lock, flags);
clear_slob_page(sp);
free_slob_page(sp);
slob_free_pages(b, 0);
return;
}
if (!slob_page_free(sp)) {
sp->units = units;
sp->freelist = b;
set_slob(b, units,
(void *)((unsigned long)(b +
SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK));
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
set_slob_page_free(sp, slob_list);
goto out;
}
sp->units += units;
if (b < (slob_t *)sp->freelist) {
if (b + units == sp->freelist) {
units += slob_units(sp->freelist);
sp->freelist = slob_next(sp->freelist);
}
set_slob(b, units, sp->freelist);
sp->freelist = b;
} else {
prev = sp->freelist;
next = slob_next(prev);
while (b > next) {
prev = next;
next = slob_next(prev);
}
if (!slob_last(prev) && b + units == next) {
units += slob_units(next);
set_slob(b, units, slob_next(next));
} else
set_slob(b, units, next);
if (prev + slob_units(prev) == b) {
units = slob_units(b) + slob_units(prev);
set_slob(prev, units, slob_next(b));
} else
set_slob(prev, slob_units(prev), b);
}
out:
spin_unlock_irqrestore(&slob_lock, flags);
}
static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
{
struct page *sp;
struct list_head *prev;
struct list_head *slob_list;
slob_t *b = NULL;
unsigned long flags;
if (size < SLOB_BREAK1)
slob_list = &free_slob_small;
else if (size < SLOB_BREAK2)
slob_list = &free_slob_medium;
else
slob_list = &free_slob_large;
spin_lock_irqsave(&slob_lock, flags);
list_for_each_entry(sp, slob_list, list) {
#ifdef CONFIG_NUMA
/*
* If there's a node specification, search for a partial
* page with a matching node id in the freelist.
*/
if (node != NUMA_NO_NODE && page_to_nid(sp) != node)
continue;
#endif
if (sp->units < SLOB_UNITS(size))
continue;
prev = sp->list.prev;
b = slob_page_alloc(sp, size, align);
if (!b)
continue;
if (prev != slob_list->prev &&
slob_list->next != prev->next)
list_move_tail(slob_list, prev->next);
break;
}
spin_unlock_irqrestore(&slob_lock, flags);
if (!b) {
b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node);
if (!b)
return NULL;
sp = slob_page(b);
set_slob_page(sp);
spin_lock_irqsave(&slob_lock, flags);
sp->units = SLOB_UNITS(PAGE_SIZE);
sp->freelist = b;
INIT_LIST_HEAD(&sp->list);
set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
set_slob_page_free(sp, slob_list);
b = slob_page_alloc(sp, size, align);
BUG_ON(!b);
spin_unlock_irqrestore(&slob_lock, flags);
}
if (unlikely((gfp & __GFP_ZERO) && b))
memset(b, 0, size);
return b;
}
/*
* Allocate a slob block within a given slob_page sp.
*
* We modified the slob_page_alloc function to find the
* best block on a given page. We understand that it is
* searching through a page's free blocks twice (once
* from the helper, and a second time for this function).
* We make a best version of all the variables in the
* function to keep track of the best block. Then we go
* through the entire block list and return the best block.
*/
static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
{
slob_t *prev, *cur, *aligned = NULL;
int delta = 0, units = SLOB_UNITS(size);
slob_t *best_prev = NULL, *best_cur = NULL, *best_aligned = NULL;
int best_delta = 0;
slobidx_t best_fit = 0;
for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
slobidx_t avail = slob_units(cur);
if (align) {
aligned = (slob_t *)ALIGN((unsigned long)cur, align);
delta = aligned - cur;
}
#ifdef SLOB_BEST_FIT_ALG
if (avail >= units + delta && (best_cur == NULL || avail - (units + delta) < best_fit) ) { /* room enough? */
#else
if (avail >= units + delta) { /* room enough? */
#endif
best_prev = prev;
best_cur = cur;
best_aligned = aligned;
best_delta = delta;
best_fit = avail - (units + delta);
#ifdef SLOB_BEST_FIT_ALG
}
if (slob_last(cur)) {
if (best_cur != NULL) {
#endif
slob_t *best_next = NULL;
slobidx_t best_avail = slob_units(best_cur);
if (best_delta) { /* need to fragment head to align? */
best_next = slob_next(best_cur);
set_slob(best_aligned, best_avail - best_delta, best_next);
set_slob(best_cur, best_delta, best_aligned);
best_prev = best_cur;
best_cur = best_aligned;
best_avail = slob_units(best_cur);
}
best_next = slob_next(best_cur);
if (best_avail == units) { /* exact fit? unlink. */
if (best_prev)
set_slob(best_prev, slob_units(best_prev), best_next);
else
sp->free = best_next;
} else { /* fragment */
if (best_prev)
set_slob(best_prev, slob_units(best_prev), best_cur + units);
else
sp->free = best_cur + units;
set_slob(best_cur + units, best_avail - units, best_next);
}
sp->units -= units;
if (!sp->units)
clear_slob_page_free(sp);
return best_cur;
#ifdef SLOB_BEST_FIT_ALG
}
#else
}
if (slob_last(cur)) {
#endif
return NULL;
}
}
}
/*
* The helper function, slob_page_best_fit_check, goes
* through the page's list of blocks and returns a number.
* The number will either be -1, 0, or some positive integer. -1
* means that there is no big enough block. 0 means a perfect
* fitted block. Any positive integer represents the amount
* that will be left over in the block if allocation happens. We
* either want this number to be 0 or as low as possible for
* best-fit algorithm.
*/
static int slob_page_best_fit_check(struct slob_page *sp, size_t size, int align)
{
slob_t *prev, *cur, *aligned = NULL;
int delta = 0, units = SLOB_UNITS(size);
slob_t *best_cur = NULL;
slobidx_t best_fit = 0;
for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
slobidx_t avail = slob_units(cur);
if (align) {
aligned = (slob_t *)ALIGN((unsigned long)cur, align);
delta = aligned - cur;
}
if (avail >= units + delta && (best_cur == NULL || avail - (units + delta) < best_fit) ) { /* room enough? */
best_cur = cur;
best_fit = avail - (units + delta);
if(best_fit == 0)
return 0;
}
if (slob_last(cur)) {
if (best_cur != NULL)
return best_fit;
return -1;
}
}
}