new file mode 100644
--- /dev/null
+++ b/src/core/ngx_slab.c
@@ -0,0 +1,685 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+/*
+
+                         12
+    2048   2             11
+    1024   4             10
+    512    8             9
+    256   16             8
+
+    128   32   4   32    7
+
+    64    64   8   63    6      1
+    32   128  16  127    5      1
+    16   256  32  254    4      2
+    8    512  64  504    3      8
+
+ */
+
+
+#define NGX_SLAB_PAGE_MASK   3
+#define NGX_SLAB_PAGE        0
+#define NGX_SLAB_BIG         1
+#define NGX_SLAB_EXACT       2
+#define NGX_SLAB_SMALL       3
+
+#if (NGX_PTR_SIZE == 4)
+
+#define NGX_SLAB_PAGE_FREE   0
+#define NGX_SLAB_PAGE_BUSY   0xffffffff
+#define NGX_SLAB_PAGE_START  0x80000000
+
+#define NGX_SLAB_SHIFT_MASK  0x0000000f
+#define NGX_SLAB_MAP_MASK    0xffff0000
+#define NGX_SLAB_MAP_SHIFT   16
+
+#define NGX_SLAB_BUSY        0xffffffff
+
+#else /* (NGX_PTR_SIZE == 8) */
+
+#define NGX_SLAB_PAGE_FREE   0
+#define NGX_SLAB_PAGE_BUSY   0xffffffffffffffff
+#define NGX_SLAB_PAGE_START  0x8000000000000000
+
+#define NGX_SLAB_SHIFT_MASK  0x000000000000000f
+#define NGX_SLAB_MAP_MASK    0xffffffff00000000
+#define NGX_SLAB_MAP_SHIFT   32
+
+#define NGX_SLAB_BUSY        0xffffffffffffffff
+
+#endif
+
+
+#if (NGX_DEBUG_MALLOC)
+#define ngx_slab_junk(p, size)  ngx_memset(p, 0xD0, size)
+#else
+#define ngx_slab_junk(p, size)
+#endif
+
+static ngx_slab_page_t *ngx_slab_alloc_pages(ngx_slab_pool_t *pool,
+    ngx_uint_t pages);
+static void ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
+    ngx_uint_t pages);
+
+
+static ngx_uint_t  ngx_slab_max_size;
+static ngx_uint_t  ngx_slab_exact_size;
+static ngx_uint_t  ngx_slab_exact_shift;
+
+
+void
+ngx_slab_init(ngx_slab_pool_t *pool)
+{
+    u_char           *p;
+    size_t            size;
+    ngx_int_t         m;
+    ngx_uint_t        i, n, pages;
+    ngx_slab_page_t  *slots;
+
+    /* STUB */
+    if (ngx_slab_max_size == 0) {
+        ngx_slab_max_size = ngx_pagesize / 2;
+        ngx_slab_exact_size = ngx_pagesize / (8 * sizeof(uintptr_t));
+        for (n = ngx_slab_exact_size; n >>= 1; ngx_slab_exact_shift++) {
+            /* void */
+        }
+    }
+    /**/
+
+    pool->min_size = 1 << pool->min_shift;
+
+    p = (u_char *) pool + sizeof(ngx_slab_pool_t);
+    size = pool->end - p;
+
+    ngx_slab_junk(p, size);
+
+    slots = (ngx_slab_page_t *) p;
+    n = ngx_pagesize_shift - pool->min_shift;
+
+    for (i = 0; i < n; i++) {
+        slots[i].slab = 0;
+        slots[i].next = &slots[i];
+        slots[i].prev = 0;
+    }
+
+    p += n * sizeof(ngx_slab_page_t);
+
+    /* STUB: possible overflow on 64-bit platform */
+    pages = (ngx_uint_t) ((uint64_t) size * ngx_pagesize
+                          / (ngx_pagesize + sizeof(ngx_slab_page_t))
+                              / ngx_pagesize);
+
+    ngx_memzero(p, pages * sizeof(ngx_slab_page_t));
+
+    pool->pages = (ngx_slab_page_t *) p;
+
+    pool->free.prev = 0;
+    pool->free.next = (ngx_slab_page_t *) p;
+
+    pool->pages->slab = pages;
+    pool->pages->next = &pool->free;
+    pool->pages->prev = (uintptr_t) &pool->free;
+
+    pool->start = (u_char *)
+                      ngx_align((uintptr_t) p + pages * sizeof(ngx_slab_page_t),
+                                 ngx_pagesize);
+
+    m = pages - (pool->end - pool->start) / ngx_pagesize;
+    if (m > 0) {
+        pages -= m;
+        pool->pages->slab = pages;
+    }
+
+#if 0
+    ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, "slab: %p, %p, %ui, %d",
+                  pool, pool->start, pages,
+                  (pool->end - pool->start) / ngx_pagesize - pages);
+#endif
+}
+
+
+void *
+ngx_slab_alloc(ngx_slab_pool_t *pool, size_t size)
+{
+    size_t            s;
+    uintptr_t         p, mask, *bitmap;
+    ngx_uint_t        i, n, m, slot, shift, map;
+    ngx_slab_page_t  *page, *prev, *slots;
+
+    ngx_shmtx_lock(&pool->mutex);
+
+    if (size >= ngx_slab_max_size) {
+        page = ngx_slab_alloc_pages(pool, (size + ngx_pagesize - 1)
+                                          >> ngx_pagesize_shift);
+        if (page) {
+            p = (page - pool->pages) << ngx_pagesize_shift;
+            p += (uintptr_t) pool->start;
+
+        } else {
+            p = 0;
+        }
+
+        goto done;
+    }
+
+    if (size > pool->min_size) {
+        shift = 1;
+        for (s = size - 1; s >>= 1; shift++) { /* void */ }
+        slot = shift - pool->min_shift;
+
+    } else {
+        size = pool->min_size;
+        shift = pool->min_shift;
+        slot = 0;
+    }
+
+    ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
+                   "slab alloc: %uz slot: %ui", size, slot);
+
+    slots = (ngx_slab_page_t *) ((u_char *) pool + sizeof(ngx_slab_pool_t));
+    page = slots[slot].next;
+
+#if 0
+    ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0,
+                   "slab alloc: page %p next: %p", page, page->next);
+#endif
+
+    if (page->next != page) {
+
+        if (size < ngx_slab_exact_size) {
+
+            do {
+                p = (page - pool->pages) << ngx_pagesize_shift;
+                bitmap = (uintptr_t *) (pool->start + p);
+
+                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 <<= 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_t *)
+                                            (page->prev & ~NGX_SLAB_PAGE_MASK);
+                                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 (size == ngx_slab_exact_size) {
+
+            do {
+                if (page->slab != NGX_SLAB_BUSY) {
+
+                    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_t *)
+                                            (page->prev & ~NGX_SLAB_PAGE_MASK);
+                            prev->next = page->next;
+                            page->next->prev = page->prev;
+
+                            page->next = NULL;
+                            page->prev = NGX_SLAB_EXACT;
+                        }
+
+                        p = (page - pool->pages) << ngx_pagesize_shift;
+                        p += i << shift;
+                        p += (uintptr_t) pool->start;
+
+                        goto done;
+                    }
+                }
+
+                page = page->next;
+
+            } while (page);
+
+        } else { /* size < ngx_pagesize */
+
+            n = ngx_pagesize_shift - (page->slab & NGX_SLAB_SHIFT_MASK);
+            n = 1 << n;
+            n = (1 << n) - 1;
+            mask = n << NGX_SLAB_MAP_SHIFT;
+
+            do {
+                if ((page->slab & NGX_SLAB_MAP_MASK) != mask) {
+
+                    for (m = 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_t *)
+                                            (page->prev & ~NGX_SLAB_PAGE_MASK);
+                            prev->next = page->next;
+                            page->next->prev = page->prev;
+
+                            page->next = NULL;
+                            page->prev = NGX_SLAB_BIG;
+                        }
+
+                        p = (page - pool->pages) << ngx_pagesize_shift;
+                        p += i << shift;
+                        p += (uintptr_t) pool->start;
+
+                        goto done;
+                    }
+                }
+
+                page = page->next;
+
+            } while (page);
+        }
+    }
+
+    page = ngx_slab_alloc_pages(pool, 1);
+
+    if (page) {
+        if (size < ngx_slab_exact_size) {
+            p = (page - pool->pages) << ngx_pagesize_shift;
+            bitmap = (uintptr_t *) (pool->start + p);
+
+            s = 1 << shift;
+            n = (1 << (ngx_pagesize_shift - shift)) / 8 / s;
+
+            if (n == 0) {
+                n = 1;
+            }
+
+            bitmap[0] = (2 << n) - 1;
+
+            map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8);
+
+            for (i = 1; i < map; i++) {
+                bitmap[i] = 0;
+            }
+
+            page->slab = shift;
+            page->next = &slots[slot];
+            page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL;
+
+            slots[slot].next = page;
+
+            p = ((page - pool->pages) << ngx_pagesize_shift) + s * n;
+            p += (uintptr_t) pool->start;
+
+            goto done;
+
+        } else if (size == ngx_slab_exact_size) {
+
+            page->slab = 1;
+            page->next = &slots[slot];
+            page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT;
+
+            slots[slot].next = page;
+
+            p = (page - pool->pages) << ngx_pagesize_shift;
+            p += (uintptr_t) pool->start;
+
+            goto done;
+
+        } else { /* size < ngx_pagesize */
+
+            page->slab = (1 << NGX_SLAB_MAP_SHIFT) | shift;
+            page->next = &slots[slot];
+            page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG;
+
+            slots[slot].next = page;
+
+            p = (page - pool->pages) << ngx_pagesize_shift;
+            p += (uintptr_t) pool->start;
+
+            goto done;
+        }
+    }
+
+    p = 0;
+
+done:
+
+    ngx_shmtx_unlock(&pool->mutex);
+
+    ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %p", p);
+
+    return (void *) p;
+}
+
+
+void
+ngx_slab_free(ngx_slab_pool_t *pool, void *p)
+{
+    size_t            size;
+    uintptr_t         slab, *bitmap;
+    ngx_uint_t        n, m, type, slot, shift, map;
+    ngx_slab_page_t  *slots, *page;
+
+    ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab free: %p", p);
+
+    ngx_shmtx_lock(&pool->mutex);
+
+    if ((u_char *) p < pool->start || (u_char *) p > pool->end) {
+        ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
+                      "ngx_slab_free(): outside of pool");
+        goto fail;
+    }
+
+    n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
+    page = &pool->pages[n];
+    slab = page->slab;
+    type = page->prev & NGX_SLAB_PAGE_MASK;
+
+    switch (type) {
+
+    case NGX_SLAB_SMALL:
+
+        shift = slab & NGX_SLAB_SHIFT_MASK;
+        size = 1 << shift;
+
+        if ((uintptr_t) p & (size - 1)) {
+            goto wrong_chunk;
+        }
+
+        n = ((uintptr_t) p & (ngx_pagesize - 1)) >> shift;
+        m = 1 << (n & (sizeof(uintptr_t) * 8 - 1));
+        n /= (sizeof(uintptr_t) * 8);
+        bitmap = (uintptr_t *) ((uintptr_t) p & ~(ngx_pagesize - 1));
+
+        if (bitmap[n] & m) {
+
+            if (page->next == NULL) {
+                slots = (ngx_slab_page_t *)
+                                   ((u_char *) pool + sizeof(ngx_slab_pool_t));
+                slot = shift - pool->min_shift;
+
+                page->next = slots[slot].next;
+                slots[slot].next = page;
+
+                page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL;
+                page->next->prev = (uintptr_t) page | NGX_SLAB_SMALL;
+            }
+
+            bitmap[n] &= ~m;
+
+            n = (1 << (ngx_pagesize_shift - shift)) / 8 / (1 << shift);
+
+            if (n == 0) {
+                n = 1;
+            }
+
+            if (bitmap[0] & ~((1 << n) - 1)) {
+                goto done;
+            }
+
+            map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8);
+
+            for (n = 1; n < map; n++) {
+                if (bitmap[n]) {
+                    goto done;
+                }
+            }
+
+            ngx_slab_free_pages(pool, page, 1);
+
+            goto done;
+        }
+
+        goto chunk_already_free;
+
+    case NGX_SLAB_EXACT:
+
+        m = 1 << (((uintptr_t) p & (ngx_pagesize - 1)) >> ngx_slab_exact_shift);
+        size = ngx_slab_exact_size;
+
+        if ((uintptr_t) p & (size - 1)) {
+            goto wrong_chunk;
+        }
+
+        if (slab & m) {
+            if (slab == NGX_SLAB_BUSY) {
+                slots = (ngx_slab_page_t *)
+                                   ((u_char *) pool + sizeof(ngx_slab_pool_t));
+                slot = ngx_slab_exact_shift - pool->min_shift;
+
+                page->next = slots[slot].next;
+                slots[slot].next = page;
+
+                page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT;
+                page->next->prev = (uintptr_t) page | NGX_SLAB_EXACT;
+            }
+
+            page->slab &= ~m;
+
+            if (page->slab) {
+                goto done;
+            }
+
+            ngx_slab_free_pages(pool, page, 1);
+
+            goto done;
+        }
+
+        goto chunk_already_free;
+
+    case NGX_SLAB_BIG:
+
+        shift = slab & NGX_SLAB_SHIFT_MASK;
+        size = 1 << shift;
+
+        if ((uintptr_t) p & (size - 1)) {
+            goto wrong_chunk;
+        }
+
+        m = 1 << ((((uintptr_t) p & (ngx_pagesize - 1)) >> shift)
+                     + NGX_SLAB_MAP_SHIFT);
+
+        if (slab & m) {
+
+            if (page->next == NULL) {
+                slots = (ngx_slab_page_t *)
+                                   ((u_char *) pool + sizeof(ngx_slab_pool_t));
+                slot = shift - pool->min_shift;
+
+                page->next = slots[slot].next;
+                slots[slot].next = page;
+
+                page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG;
+                page->next->prev = (uintptr_t) page | NGX_SLAB_BIG;
+            }
+
+            page->slab &= ~m;
+
+            if (page->slab & NGX_SLAB_MAP_MASK) {
+                goto done;
+            }
+
+            ngx_slab_free_pages(pool, page, 1);
+
+            goto done;
+        }
+
+        goto chunk_already_free;
+
+    case NGX_SLAB_PAGE:
+
+        if ((uintptr_t) p & (ngx_pagesize - 1)) {
+            goto wrong_chunk;
+        }
+
+        if (slab == NGX_SLAB_PAGE_FREE) {
+            ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
+                          "ngx_slab_free(): page is already free");
+            goto fail;
+        }
+
+        if (slab == NGX_SLAB_PAGE_BUSY) {
+            ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
+                          "ngx_slab_free(): pointer to wrong page");
+            goto fail;
+        }
+
+        n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
+        size = slab & ~NGX_SLAB_PAGE_START;
+
+        ngx_slab_free_pages(pool, &pool->pages[n], size);
+
+        size <<= ngx_pagesize_shift;
+
+        goto done;
+    }
+
+    /* not reached */
+
+    return;
+
+done:
+
+    ngx_slab_junk(p, size);
+
+    ngx_shmtx_unlock(&pool->mutex);
+
+    return;
+
+wrong_chunk:
+
+    ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
+                      "ngx_slab_free(): pointer to wrong chunk");
+
+    goto fail;
+
+chunk_already_free:
+
+    ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
+                      "ngx_slab_free(): chunk is already free");
+
+fail:
+
+    ngx_shmtx_unlock(&pool->mutex);
+
+    return;
+}
+
+
+static ngx_slab_page_t *
+ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages)
+{
+    ngx_slab_page_t  *page, *p;
+
+    for (page = pool->free.next; page != &pool->free; page = page->next) {
+
+        if (page->slab >= pages) {
+
+            if (page->slab > pages) {
+                page[pages].slab = page->slab - pages;
+                page[pages].next = page->next;
+                page[pages].prev = page->prev;
+
+                p = (ngx_slab_page_t *) page->prev;
+                p->next = &page[pages];
+                page->next->prev = (uintptr_t) &page[pages];
+
+            } else {
+                p = (ngx_slab_page_t *) page->prev;
+                p->next = page->next;
+                page->next->prev = page->prev;
+            }
+
+            page->slab = pages | NGX_SLAB_PAGE_START;
+
+#if (NGX_DEBUG)
+            page->next = NULL;
+            page->prev = NGX_SLAB_PAGE;
+#endif
+
+            if (--pages == 0) {
+                return page;
+            }
+
+            for (p = page + 1; pages; pages--) {
+                p->slab = NGX_SLAB_PAGE_BUSY;
+#if (NGX_DEBUG)
+                p->next = NULL;
+                p->prev = NGX_SLAB_PAGE;
+#endif
+                p++;
+            }
+
+            return page;
+        }
+    }
+
+    ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, NGX_ENOMEM,
+                      "ngx_slab_alloc(): failed");
+    return NULL;
+}
+
+
+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;
+
+    page->slab = pages--;
+
+    if (pages) {
+        ngx_memzero(&page[1], pages * sizeof(ngx_slab_page_t));
+    }
+
+    prev = (ngx_slab_page_t *) (page->prev & ~NGX_SLAB_PAGE_MASK);
+    prev->next = page->next;
+
+    page->next = pool->free.next;
+    pool->free.next = page;
+
+    page->prev = page->next->prev;
+    page->next->prev = (uintptr_t) page;
+}