$request_time has millisecond precision

src/http/ngx_http_request.h

diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 414efd7..a380ac0 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -342,7 +342,8 @@
     ngx_http_request_body_t          *request_body;
 
     time_t                            lingering_time;
-    time_t                            start_time;
+    time_t                            start_sec;
+    ngx_msec_t                        start_msec;
 
     ngx_uint_t                        method;
     ngx_uint_t                        http_version;