--- a/auto/os/features
+++ b/auto/os/features
@@ -170,3 +170,23 @@ if [ $ngx_found = no ]; then
         CRYPT_LIB="-lcrypt"
     fi
 fi
+
+
+ngx_feature="O_DIRECT"
+ngx_feature_name="NGX_HAVE_O_DIRECT"
+ngx_feature_run=no
+ngx_feature_incs="#include <fcntl.h>"
+ngx_feature_path=
+ngx_feature_libs=
+ngx_feature_test="fcntl(0, F_SETFL, O_DIRECT);"
+. auto/feature
+
+
+ngx_feature="F_NOCACHE"
+ngx_feature_name="NGX_HAVE_F_NOCACHE"
+ngx_feature_run=no
+ngx_feature_incs="#include <fcntl.h>"
+ngx_feature_path=
+ngx_feature_libs=
+ngx_feature_test="fcntl(0, F_NOCACHE, 1);"
+. auto/feature

--- a/src/core/ngx_open_file_cache.c
+++ b/src/core/ngx_open_file_cache.c
@@ -497,6 +497,13 @@ ngx_open_and_stat_file(u_char *name, ngx
 
     } else {
         of->fd = fd;
+
+        if (of->directio <= ngx_file_size(&fi)) {
+            if (ngx_directio(fd) == -1) {
+                ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
+                              ngx_directio_n " \"%s\" failed", name);
+            }
+        }
     }
 
 done:

--- a/src/core/ngx_open_file_cache.h
+++ b/src/core/ngx_open_file_cache.h
@@ -17,6 +17,7 @@ typedef struct {
     ngx_file_uniq_t          uniq;
     time_t                   mtime;
     off_t                    size;
+    off_t                    directio;
     ngx_err_t                err;
 
     time_t                   valid;

--- a/src/core/ngx_output_chain.c
+++ b/src/core/ngx_output_chain.c
@@ -32,6 +32,7 @@ ngx_output_chain(ngx_output_chain_ctx_t 
     size_t        size;
     ngx_int_t     rc, last;
     ngx_uint_t    recycled;
+    ngx_buf_t    *b;
     ngx_chain_t  *cl, *out, **last_out;
 
     if (ctx->in == NULL && ctx->busy == NULL) {
@@ -161,13 +162,29 @@ ngx_output_chain(ngx_output_chain_ctx_t 
                         }
                     }
 
-                    ctx->buf = ngx_create_temp_buf(ctx->pool, size);
-                    if (ctx->buf == NULL) {
+                    b = ngx_calloc_buf(ctx->pool);
+                    if (b == NULL) {
                         return NGX_ERROR;
                     }
 
-                    ctx->buf->tag = ctx->tag;
-                    ctx->buf->recycled = recycled;
+                    /*
+                     * allocate block aligned to a disk sector size
+                     * to enable O_DIRECT
+                     */
+
+                    b->start = ngx_pmemalign(ctx->pool, size, 512);
+                    if (b->start == NULL) {
+                        return NGX_ERROR;
+                    }
+
+                    b->pos = b->start;
+                    b->last = b->start;
+                    b->end = b->last + size;
+                    b->temporary = 1;
+                    b->tag = ctx->tag;
+                    b->recycled = recycled;
+
+                    ctx->buf = b;
                     ctx->allocated++;
                 }
             }

--- a/src/core/ngx_palloc.c
+++ b/src/core/ngx_palloc.c
@@ -195,17 +195,35 @@ ngx_palloc_large(ngx_pool_t *pool, size_
     void              *p;
     ngx_pool_large_t  *large;
 
-#if 0
-    p = ngx_memalign(ngx_pagesize, size, pool->log);
-    if (p == NULL) {
-        return NULL;
-    }
-#else
     p = ngx_alloc(size, pool->log);
     if (p == NULL) {
         return NULL;
     }
-#endif
+
+    large = ngx_palloc(pool, sizeof(ngx_pool_large_t));
+    if (large == NULL) {
+        ngx_free(p);
+        return NULL;
+    }
+
+    large->alloc = p;
+    large->next = pool->large;
+    pool->large = large;
+
+    return p;
+}
+
+
+void *
+ngx_pmemalign(ngx_pool_t *pool, size_t size, size_t alignment)
+{
+    void              *p;
+    ngx_pool_large_t  *large;
+
+    p = ngx_memalign(alignment, size, pool->log);
+    if (p == NULL) {
+        return NULL;
+    }
 
     large = ngx_palloc(pool, sizeof(ngx_pool_large_t));
     if (large == NULL) {

--- a/src/core/ngx_palloc.h
+++ b/src/core/ngx_palloc.h
@@ -77,6 +77,7 @@ void ngx_destroy_pool(ngx_pool_t *pool);
 void *ngx_palloc(ngx_pool_t *pool, size_t size);
 void *ngx_pnalloc(ngx_pool_t *pool, size_t size);
 void *ngx_pcalloc(ngx_pool_t *pool, size_t size);
+void *ngx_pmemalign(ngx_pool_t *pool, size_t size, size_t alignment);
 ngx_int_t ngx_pfree(ngx_pool_t *pool, void *p);
 
 

--- a/src/http/modules/ngx_http_flv_module.c
+++ b/src/http/modules/ngx_http_flv_module.c
@@ -107,6 +107,7 @@ ngx_http_flv_handler(ngx_http_request_t 
 
     ngx_memzero(&of, sizeof(ngx_open_file_info_t));
 
+    of.directio = clcf->directio;
     of.valid = clcf->open_file_cache_valid;
     of.min_uses = clcf->open_file_cache_min_uses;
     of.errors = clcf->open_file_cache_errors;

--- a/src/http/modules/ngx_http_gzip_static_module.c
+++ b/src/http/modules/ngx_http_gzip_static_module.c
@@ -121,6 +121,7 @@ ngx_http_gzip_static_handler(ngx_http_re
 
     ngx_memzero(&of, sizeof(ngx_open_file_info_t));
 
+    of.directio = clcf->directio;
     of.valid = clcf->open_file_cache_valid;
     of.min_uses = clcf->open_file_cache_min_uses;
     of.errors = clcf->open_file_cache_errors;

--- a/src/http/modules/ngx_http_index_module.c
+++ b/src/http/modules/ngx_http_index_module.c
@@ -210,6 +210,7 @@ ngx_http_index_handler(ngx_http_request_
 
         ngx_memzero(&of, sizeof(ngx_open_file_info_t));
 
+        of.directio = clcf->directio;
         of.valid = clcf->open_file_cache_valid;
         of.min_uses = clcf->open_file_cache_min_uses;
         of.errors = clcf->open_file_cache_errors;

--- a/src/http/modules/ngx_http_static_module.c
+++ b/src/http/modules/ngx_http_static_module.c
@@ -98,6 +98,7 @@ ngx_http_static_handler(ngx_http_request
 
     ngx_memzero(&of, sizeof(ngx_open_file_info_t));
 
+    of.directio = clcf->directio;
     of.valid = clcf->open_file_cache_valid;
     of.min_uses = clcf->open_file_cache_min_uses;
     of.errors = clcf->open_file_cache_errors;

--- a/src/http/modules/perl/nginx.xs
+++ b/src/http/modules/perl/nginx.xs
@@ -652,6 +652,7 @@ sendfile(r, filename, offset = -1, bytes
 
     ngx_memzero(&of, sizeof(ngx_open_file_info_t));
 
+    of.directio = clcf->directio;
     of.valid = clcf->open_file_cache_valid;
     of.min_uses = clcf->open_file_cache_min_uses;
     of.errors = clcf->open_file_cache_errors;

--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -54,6 +54,8 @@ static char *ngx_http_core_server_name(n
 static char *ngx_http_core_root(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
 static char *ngx_http_core_limit_except(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
+static char *ngx_http_core_directio(ngx_conf_t *cf, ngx_command_t *cmd,
+    void *conf);
 static char *ngx_http_core_error_page(ngx_conf_t *cf, ngx_command_t *cmd,
     void *conf);
 static char *ngx_http_core_open_file_cache(ngx_conf_t *cf, ngx_command_t *cmd,
@@ -353,6 +355,13 @@ static ngx_command_t  ngx_http_core_comm
       offsetof(ngx_http_core_loc_conf_t, sendfile_max_chunk),
       NULL },
 
+    { ngx_string("directio"),
+      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      ngx_http_core_directio,
+      NGX_HTTP_LOC_CONF_OFFSET,
+      0,
+      NULL },
+
     { ngx_string("tcp_nopush"),
       NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
       ngx_conf_set_flag_slot,
@@ -2586,6 +2595,7 @@ ngx_http_core_create_loc_conf(ngx_conf_t
     lcf->client_body_in_file_only = NGX_CONF_UNSET;
     lcf->sendfile = NGX_CONF_UNSET;
     lcf->sendfile_max_chunk = NGX_CONF_UNSET_SIZE;
+    lcf->directio = NGX_CONF_UNSET;
     lcf->tcp_nopush = NGX_CONF_UNSET;
     lcf->tcp_nodelay = NGX_CONF_UNSET;
     lcf->send_timeout = NGX_CONF_UNSET_MSEC;
@@ -2774,6 +2784,8 @@ ngx_http_core_merge_loc_conf(ngx_conf_t 
     ngx_conf_merge_value(conf->sendfile, prev->sendfile, 0);
     ngx_conf_merge_size_value(conf->sendfile_max_chunk,
                               prev->sendfile_max_chunk, 0);
+    ngx_conf_merge_off_value(conf->directio, prev->directio,
+                              NGX_MAX_OFF_T_VALUE);
     ngx_conf_merge_value(conf->tcp_nopush, prev->tcp_nopush, 0);
     ngx_conf_merge_value(conf->tcp_nodelay, prev->tcp_nodelay, 1);
 
@@ -3340,6 +3352,33 @@ ngx_http_core_limit_except(ngx_conf_t *c
 
 
 static char *
+ngx_http_core_directio(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
+{
+    ngx_http_core_loc_conf_t *clcf = conf;
+
+    ngx_str_t  *value;
+
+    if (clcf->directio != NGX_CONF_UNSET) {
+        return "is duplicate";
+    }
+
+    value = cf->args->elts;
+
+    if (ngx_strcmp(value[1].data, "off") == 0) {
+        clcf->directio = NGX_MAX_OFF_T_VALUE;
+        return NGX_CONF_OK;
+    }
+
+    clcf->directio = ngx_parse_offset(&value[1]);
+    if (clcf->directio == (off_t) NGX_ERROR) {
+        return "invalid value";
+    }
+
+    return NGX_CONF_OK;
+}
+
+
+static char *
 ngx_http_core_error_page(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
     ngx_http_core_loc_conf_t *lcf = conf;

--- a/src/http/ngx_http_core_module.h
+++ b/src/http/ngx_http_core_module.h
@@ -265,6 +265,7 @@ struct ngx_http_core_loc_conf_s {
     ngx_str_t     default_type;
 
     off_t         client_max_body_size;    /* client_max_body_size */
+    off_t         directio;                /* directio */
 
     size_t        client_body_buffer_size; /* client_body_buffer_size */
     size_t        send_lowat;              /* send_lowat */

--- a/src/http/ngx_http_script.c
+++ b/src/http/ngx_http_script.c
@@ -996,6 +996,7 @@ ngx_http_script_file_code(ngx_http_scrip
 
     ngx_memzero(&of, sizeof(ngx_open_file_info_t));
 
+    of.directio = clcf->directio;
     of.valid = clcf->open_file_cache_valid;
     of.min_uses = clcf->open_file_cache_min_uses;
     of.errors = clcf->open_file_cache_errors;

--- a/src/os/unix/ngx_alloc.h
+++ b/src/os/unix/ngx_alloc.h
@@ -21,8 +21,8 @@ void *ngx_calloc(size_t size, ngx_log_t 
 /*
  * Linux has memalign() or posix_memalign()
  * Solaris has memalign()
- * FreeBSD has not memalign() or posix_memalign() but its malloc() alignes
- * allocations bigger than page size at the page boundary.
+ * FreeBSD 7.0 has posix_memalign(), besides, early version's malloc()
+ * aligns allocations bigger than page size at the page boundary
  */
 
 #if (NGX_HAVE_POSIX_MEMALIGN || NGX_HAVE_MEMALIGN)

--- a/src/os/unix/ngx_files.c
+++ b/src/os/unix/ngx_files.c
@@ -351,3 +351,22 @@ ngx_unlock_fd(ngx_fd_t fd)
 
     return 0;
 }
+
+
+#if (NGX_HAVE_O_DIRECT)
+
+ngx_int_t
+ngx_directio(ngx_fd_t fd)
+{
+    int  flags;
+
+    flags = fcntl(fd, F_GETFL);
+
+    if (flags == -1) {
+        return -1;
+    }
+
+    return fcntl(fd, F_SETFL, flags | O_DIRECT);
+}
+
+#endif

--- a/src/os/unix/ngx_files.h
+++ b/src/os/unix/ngx_files.h
@@ -189,4 +189,22 @@ ngx_err_t ngx_unlock_fd(ngx_fd_t fd);
 #define ngx_unlock_fd_n          "fcntl(F_SETLK, F_UNLCK)"
 
 
+#if (NGX_HAVE_O_DIRECT)
+
+ngx_int_t ngx_directio(ngx_fd_t fd);
+#define ngx_directio_n           "fcntl(O_DIRECT)"
+
+#elif (NGX_HAVE_F_NOCACHE)
+
+#define ngx_directio(fd)         fcntl(fd, F_NOCACHE, 1)
+#define ngx_directio_n           "fcntl(F_NOCACHE)"
+
+#else
+
+#define ngx_directio(fd)         0
+#define ngx_directio_n           "ngx_directio_n"
+
+#endif
+
+
 #endif /* _NGX_FILES_H_INCLUDED_ */

--- a/src/os/win32/ngx_files.h
+++ b/src/os/win32/ngx_files.h
@@ -200,7 +200,7 @@ typedef struct {
 
 
 ngx_int_t ngx_open_glob(ngx_glob_t *gl);
-#define ngx_open_glob_n          "FindFirstFile()"
+#define ngx_open_glob_n             "FindFirstFile()"
 
 ngx_int_t ngx_read_glob(ngx_glob_t *gl, ngx_str_t *name);
 void ngx_close_glob(ngx_glob_t *gl);
@@ -216,4 +216,8 @@ ssize_t ngx_write_chain_to_file(ngx_file
     off_t offset, ngx_pool_t *pool);
 
 
+#define ngx_directio(fd)            0
+#define ngx_directio_n              "ngx_directio_n"
+
+
 #endif /* _NGX_FILES_H_INCLUDED_ */