From f6a02fbe763aec5d290aa9d9509aeec5348c7792 Mon Sep 17 00:00:00 2001
From: Ben Noordhuis <info@bnoordhuis.nl>
Date: Fri, 29 Jun 2012 02:23:39 +0200
Subject: [PATCH] linux: don't use accept4() syscall after ENOSYS

Repeatedly calling the syscall when it's not supported has a small but
measurable performance impact.

Besides, it's a silly thing to do.
---
 src/unix/core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/unix/core.c b/src/unix/core.c
index 318eb718..bf429948 100644
--- a/src/unix/core.c
+++ b/src/unix/core.c
@@ -426,6 +426,11 @@ int uv__accept(int sockfd) {
 
   while (1) {
 #if __linux__
+    static int no_accept4;
+
+    if (no_accept4)
+      goto skip;
+
     peerfd = uv__accept4(sockfd,
                          NULL,
                          NULL,
@@ -439,6 +444,9 @@ int uv__accept(int sockfd) {
 
     if (errno != ENOSYS)
       break;
+
+    no_accept4 = 1;
+skip:
 #endif
 
     peerfd = accept(sockfd, NULL, NULL);