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Slab: simplified allocation from slots.

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Removed code that would cause an endless loop, and removed condition
check that is always false.  The first page in the slot list is
guaranteed to satisfy an allocation.
This commit is contained in:
Ruslan Ermilov 2016-12-07 22:25:37 +03:00
parent 16de9fc3b5
commit 12abb66c41
1 changed files with 66 additions and 84 deletions
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150
src/core/ngx_slab.c
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@ -215,84 +215,71 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)
if (shift < ngx_slab_exact_shift) {
do {
bitmap = (uintptr_t *) ngx_slab_page_addr(pool, page);
bitmap = (uintptr_t *) ngx_slab_page_addr(pool, page);
map = (1 << (ngx_pagesize_shift - shift))
/ (sizeof(uintptr_t) * 8);
map = (1 << (ngx_pagesize_shift - shift))
/ (sizeof(uintptr_t) * 8);
for (n = 0; n < map; n++) {
for (n = 0; n < map; n++) {
if (bitmap[n] != NGX_SLAB_BUSY) {
for (m = 1, i = 0; m; m <<= 1, i++) {
if (bitmap[n] & m) {
continue;
}
bitmap[n] |= m;
i = ((n * sizeof(uintptr_t) * 8) << shift)
+ (i << shift);
if (bitmap[n] == NGX_SLAB_BUSY) {
for (n = n + 1; n < map; n++) {
if (bitmap[n] != NGX_SLAB_BUSY) {
p = (uintptr_t) bitmap + i;
goto done;
}
}
prev = ngx_slab_page_prev(page);
prev->next = page->next;
page->next->prev = page->prev;
page->next = NULL;
page->prev = NGX_SLAB_SMALL;
}
p = (uintptr_t) bitmap + i;
goto done;
}
}
}
page = page->next;
} while (page);
} else if (shift == ngx_slab_exact_shift) {
do {
if (page->slab != NGX_SLAB_BUSY) {
if (bitmap[n] != NGX_SLAB_BUSY) {
for (m = 1, i = 0; m; m <<= 1, i++) {
if (page->slab & m) {
if (bitmap[n] & m) {
continue;
}
page->slab |= m;
bitmap[n] |= m;
i = ((n * sizeof(uintptr_t) * 8) << shift)
+ (i << shift);
if (bitmap[n] == NGX_SLAB_BUSY) {
for (n = n + 1; n < map; n++) {
if (bitmap[n] != NGX_SLAB_BUSY) {
p = (uintptr_t) bitmap + i;
goto done;
}
}
if (page->slab == NGX_SLAB_BUSY) {
prev = ngx_slab_page_prev(page);
prev->next = page->next;
page->next->prev = page->prev;
page->next = NULL;
page->prev = NGX_SLAB_EXACT;
page->prev = NGX_SLAB_SMALL;
}
p = ngx_slab_page_addr(pool, page) + (i << shift);
p = (uintptr_t) bitmap + i;
goto done;
}
}
}
page = page->next;
} else if (shift == ngx_slab_exact_shift) {
} while (page);
for (m = 1, i = 0; m; m <<= 1, i++) {
if (page->slab & m) {
continue;
}
page->slab |= m;
if (page->slab == NGX_SLAB_BUSY) {
prev = ngx_slab_page_prev(page);
prev->next = page->next;
page->next->prev = page->prev;
page->next = NULL;
page->prev = NGX_SLAB_EXACT;
}
p = ngx_slab_page_addr(pool, page) + (i << shift);
goto done;
}
} else { /* shift > ngx_slab_exact_shift */
@ -301,38 +288,33 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size)
n = ((uintptr_t) 1 << n) - 1;
mask = n << NGX_SLAB_MAP_SHIFT;
do {
if ((page->slab & NGX_SLAB_MAP_MASK) != mask) {
for (m = (uintptr_t) 1 << NGX_SLAB_MAP_SHIFT, i = 0;
m & mask;
m <<= 1, i++)
{
if (page->slab & m) {
continue;
}
page->slab |= m;
if ((page->slab & NGX_SLAB_MAP_MASK) == mask) {
prev = ngx_slab_page_prev(page);
prev->next = page->next;
page->next->prev = page->prev;
page->next = NULL;
page->prev = NGX_SLAB_BIG;
}
p = ngx_slab_page_addr(pool, page) + (i << shift);
goto done;
}
for (m = (uintptr_t) 1 << NGX_SLAB_MAP_SHIFT, i = 0;
m & mask;
m <<= 1, i++)
{
if (page->slab & m) {
continue;
}
page = page->next;
page->slab |= m;
} while (page);
if ((page->slab & NGX_SLAB_MAP_MASK) == mask) {
prev = ngx_slab_page_prev(page);
prev->next = page->next;
page->next->prev = page->prev;
page->next = NULL;
page->prev = NGX_SLAB_BIG;
}
p = ngx_slab_page_addr(pool, page) + (i << shift);
goto done;
}
}
ngx_slab_error(pool, NGX_LOG_ALERT, "ngx_slab_alloc(): page is busy");
ngx_debug_point();
}
page = ngx_slab_alloc_pages(pool, 1);