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(-) [+] |
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--- a/src/core/ngx_slab.c +++ b/src/core/ngx_slab.c @@ -215,84 +215,71 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p 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 @@ ngx_slab_alloc_locked(ngx_slab_pool_t *p 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);