Mercurial > hg > nginx
changeset 6826:d0404c9a7675
Slab: simplified allocation from slots.
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.
author | Ruslan Ermilov <ru@nginx.com> |
---|---|
date | Wed, 07 Dec 2016 22:25:37 +0300 |
parents | f6beb55792de |
children | 0e61510c56c4 |
files | src/core/ngx_slab.c |
diffstat | 1 files changed, 66 insertions(+), 84 deletions(-) [+] |
line wrap: on
line diff
--- a/src/core/ngx_slab.c Wed Dec 07 22:25:37 2016 +0300 +++ b/src/core/ngx_slab.c Wed Dec 07 22:25:37 2016 +0300 @@ -215,84 +215,71 @@ if (shift < ngx_slab_exact_shift) { - do { - bitmap = (uintptr_t *) ngx_slab_page_addr(pool, page); - - map = (1 << (ngx_pagesize_shift - shift)) - / (sizeof(uintptr_t) * 8); - - 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; + bitmap = (uintptr_t *) ngx_slab_page_addr(pool, page); - 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; + map = (1 << (ngx_pagesize_shift - shift)) + / (sizeof(uintptr_t) * 8); - goto done; - } - } - } - - page = page->next; + for (n = 0; n < map; n++) { - } 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 (page->slab == NGX_SLAB_BUSY) { + 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_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) { + + for (m = 1, i = 0; m; m <<= 1, i++) { + if (page->slab & m) { + continue; + } + + page->slab |= m; - } while (page); + 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 @@ 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; + + if ((page->slab & NGX_SLAB_MAP_MASK) == mask) { + prev = ngx_slab_page_prev(page); + prev->next = page->next; + page->next->prev = page->prev; - } while (page); + 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);