diff --git a/ChangeLog b/ChangeLog
index eb8e4552c1..143335fed6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Dec  2 15:31:42 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* lib/net/protocol.rb (Net::BufferedIO#rbuf_fill): use
+	  read_nonblock instead of sysread wrapped by timeout to boost
+	  performance.  a patch from Aaron Patterson in [ruby-core:20191].
+	  fix #806
+
 Mon Dec  1 23:23:52 2008  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
 
 	* set 1.9.1-p5000 into version number. [ruby-dev:36998]
diff --git a/lib/net/protocol.rb b/lib/net/protocol.rb
index 0d489cdbc8..3f6f416bab 100644
--- a/lib/net/protocol.rb
+++ b/lib/net/protocol.rb
@@ -131,9 +131,15 @@ module Net # :nodoc:
     BUFSIZE = 1024 * 16
 
     def rbuf_fill
-      timeout(@read_timeout) {
-        @rbuf << @io.sysread(BUFSIZE)
-      }
+      begin
+        @rbuf << @io.read_nonblock(BUFSIZE)
+      rescue Errno::EWOULDBLOCK
+        if IO.select([@io], nil, nil, @read_timeout)
+          @rbuf << @io.read_nonblock(BUFSIZE)
+        else
+          raise Timeout::TimeoutError
+        end
+      end
     end
 
     def rbuf_consume(len)