new file mode 100644
--- /dev/null
+++ b/src/os/unix/ngx_writev_chain.c
@@ -0,0 +1,93 @@
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+ngx_chain_t *ngx_writev_chain(ngx_connection_t *c, ngx_chain_t *in)
+{
+    char            *prev;
+    size_t           size;
+    ssize_t          n;
+    off_t            sent;
+    struct iovec    *iov;
+    ngx_err_t        err;
+    ngx_array_t      io;
+    ngx_chain_t     *ce;
+
+    ngx_init_array(io, c->pool, 10, sizeof(struct iovec), NGX_CHAIN_ERROR);
+
+    prev = NULL;
+    iov = NULL;
+
+    /* create the iovec and coalesce the neighbouring chain entries */
+    for (ce = in; ce; ce = ce->next) {
+
+        if (prev == ce->hunk->pos) {
+            iov->iov_len += ce->hunk->last - ce->hunk->pos;
+            prev = ce->hunk->last;
+
+        } else {
+            ngx_test_null(iov, ngx_push_array(&io), NGX_CHAIN_ERROR);
+            iov->iov_base = ce->hunk->pos;
+            iov->iov_len = ce->hunk->last - ce->hunk->pos;
+            prev = ce->hunk->last;
+        }
+    }
+
+    n = writev(c->fd, (struct iovec *) io.elts, io.nelts);
+
+    if (n == -1) {
+        err = ngx_errno;
+        if (err == NGX_EAGAIN) {
+            ngx_log_error(NGX_LOG_INFO, c->log, err, "writev() EAGAIN");
+
+        } else if (err == NGX_EINTR) {
+            ngx_log_error(NGX_LOG_INFO, c->log, err, "writev() EINTR");
+
+        } else {
+            ngx_log_error(NGX_LOG_CRIT, c->log, err, "writev() failed");
+            return NGX_CHAIN_ERROR;
+        }
+    }
+
+    sent = n > 0 ? n : 0;
+
+#if (NGX_DEBUG_WRITE_CHAIN)
+    ngx_log_debug(c->log, "writev: %qd" _ sent);
+#endif
+
+    c->sent += sent;
+
+    for (ce = in; ce && sent > 0; ce = ce->next) {
+
+        size = ce->hunk->last - ce->hunk->pos;
+
+        if (sent >= size) {
+            sent -= size;
+
+            if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
+                ce->hunk->pos = ce->hunk->last;
+            }
+
+            if (ce->hunk->type & NGX_HUNK_FILE) {
+                ce->hunk->file_pos = ce->hunk->file_last;
+            }
+
+            continue;
+        }
+
+        if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
+            ce->hunk->pos += sent;
+        }
+
+        if (ce->hunk->type & NGX_HUNK_FILE) {
+            ce->hunk->file_pos += sent;
+        }
+
+        break;
+    }
+
+    ngx_destroy_array(&io);
+
+    return ce;
+}