From a9d1027b80489aa0175b54ecf0cbe89a67a3df4e Mon Sep 17 00:00:00 2001 From: Maxim Dounin Date: Sun, 11 Dec 2011 16:30:42 +0000 Subject: [PATCH] Microoptimization of sendfile(2) usage under FreeBSD. FreeBSD kernel checks headers/trailers pointer against NULL, not corresponding count. Passing NULL if there are no headers/trailers helps to avoid unneeded work in kernel, as well as unexpected 0 bytes GIO in traces. --- src/os/unix/ngx_freebsd_sendfile_chain.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/src/os/unix/ngx_freebsd_sendfile_chain.c b/src/os/unix/ngx_freebsd_sendfile_chain.c index 039243e96..8c98f8e38 100644 --- a/src/os/unix/ngx_freebsd_sendfile_chain.c +++ b/src/os/unix/ngx_freebsd_sendfile_chain.c @@ -246,9 +246,14 @@ ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit) } } - hdtr.headers = (struct iovec *) header.elts; + /* + * sendfile() does unneeded work if sf_hdtr's count is 0, + * but corresponding pointer is not NULL + */ + + hdtr.headers = header.nelts ? (struct iovec *) header.elts: NULL; hdtr.hdr_cnt = header.nelts; - hdtr.trailers = (struct iovec *) trailer.elts; + hdtr.trailers = trailer.nelts ? (struct iovec *) trailer.elts: NULL; hdtr.trl_cnt = trailer.nelts; /*