openresty/patches/nginx-1.7.3-slab_defrag.patch

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2014-07-14 03:35:52 +00:00
diff --git a/src/core/ngx_slab.c b/src/core/ngx_slab.c
index c3a27f7..1bde432 100644
--- a/src/core/ngx_slab.c
+++ b/src/core/ngx_slab.c
@@ -6,6 +6,7 @@
#include <ngx_config.h>
#include <ngx_core.h>
+#include <assert.h>
#define NGX_SLAB_PAGE_MASK 3
@@ -111,6 +112,7 @@ ngx_slab_init(ngx_slab_pool_t *pool)
ngx_memzero(p, pages * sizeof(ngx_slab_page_t));
pool->pages = (ngx_slab_page_t *) p;
+ pool->npages = pages;
pool->free.prev = 0;
pool->free.next = (ngx_slab_page_t *) p;
@@ -118,6 +120,7 @@ ngx_slab_init(ngx_slab_pool_t *pool)
pool->pages->slab = pages;
pool->pages->next = &pool->free;
pool->pages->prev = (uintptr_t) &pool->free;
+ pool->pages->prev_slab = 0;
pool->start = (u_char *)
ngx_align_ptr((uintptr_t) p + pages * sizeof(ngx_slab_page_t),
@@ -625,9 +628,16 @@ ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages)
if (page->slab >= pages) {
if (page->slab > pages) {
+ /* adjust the next adjacent block's "prev_slab" field */
+ p = &page[page->slab];
+ if (p < pool->pages + pool->npages) {
+ p->prev_slab = page->slab - pages;
+ }
+
page[pages].slab = page->slab - pages;
page[pages].next = page->next;
page[pages].prev = page->prev;
+ page[pages].prev_slab = pages;
p = (ngx_slab_page_t *) page->prev;
p->next = &page[pages];
@@ -651,6 +661,7 @@ ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages)
p->slab = NGX_SLAB_PAGE_BUSY;
p->next = NULL;
p->prev = NGX_SLAB_PAGE;
+ p->prev_slab = 0;
p++;
}
@@ -668,7 +679,7 @@ static void
ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
ngx_uint_t pages)
{
- ngx_slab_page_t *prev;
+ ngx_slab_page_t *prev, *p;
page->slab = pages--;
@@ -682,6 +693,53 @@ ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
page->next->prev = page->prev;
}
+ /* merge the next adjacent free block if it is free */
+
+ p = &page[page->slab];
+ if (p < pool->pages + pool->npages
+ && !(p->slab & NGX_SLAB_PAGE_START)
+ && p->next != NULL
+ && (p->prev & NGX_SLAB_PAGE_MASK) == NGX_SLAB_PAGE)
+ {
+ page->slab += p->slab;
+
+ /* remove the next adjacent block from the free list */
+
+ prev = (ngx_slab_page_t *) p->prev;
+ prev->next = p->next;
+ p->next->prev = p->prev;
+
+ /* adjust the "prev_slab" field in the next next adjacent block */
+ if (p + p->slab < pool->pages + pool->npages) {
+ p[p->slab].prev_slab = page->slab;
+ }
+
+ ngx_memzero(p, sizeof(ngx_slab_page_t));
+ }
+
+ if (page->prev_slab) {
+ /* merge the previous adjacent block if it is free */
+
+ p = page - page->prev_slab;
+ if (!(p->slab & NGX_SLAB_PAGE_START)
+ && p->next != NULL
+ && (p->prev & NGX_SLAB_PAGE_MASK) == NGX_SLAB_PAGE)
+ {
+ assert(p->slab == page->prev_slab);
+
+ p->slab += page->slab;
+ ngx_memzero(page, sizeof(ngx_slab_page_t));
+
+ /* adjust the "prev_slab" field in the next adjacent block */
+ if (p + p->slab < pool->pages + pool->npages) {
+ p[p->slab].prev_slab = p->slab;
+ }
+
+ /* skip adding "page" to the free list */
+ return;
+ }
+ }
+
page->prev = (uintptr_t) &pool->free;
page->next = pool->free.next;
diff --git a/src/core/ngx_slab.h b/src/core/ngx_slab.h
index c5e420b..287ac79 100644
--- a/src/core/ngx_slab.h
+++ b/src/core/ngx_slab.h
@@ -19,6 +19,8 @@ struct ngx_slab_page_s {
uintptr_t slab;
ngx_slab_page_t *next;
uintptr_t prev;
+ uintptr_t prev_slab;
+ /* number of pages for the previous adjacent block */
};
@@ -31,6 +33,8 @@ typedef struct {
ngx_slab_page_t *pages;
ngx_slab_page_t free;
+ ngx_uint_t npages;
+
u_char *start;
u_char *end;