diff options
Diffstat (limited to 'winsup/cygwin/net.cc')
| -rw-r--r-- | winsup/cygwin/net.cc | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/winsup/cygwin/net.cc b/winsup/cygwin/net.cc index 8ff88ba11..5c4959bdf 100644 --- a/winsup/cygwin/net.cc +++ b/winsup/cygwin/net.cc @@ -621,13 +621,20 @@ fdsock (cygheap_fdmanip& fd, const device *dev, SOCKET soc) this is no problem on 64 bit. So we set the default buffer size to the default values in current 3.x Linux versions. + NOTE 3. Setting the window size to 65535 results in extremely bad + performance for apps that send data in multiples of Kb, as they + eventually end up sending 1 byte on the network and naggle + delay + ack kicks in. For example, iperf on a 10Gb network gives only 10 + Mbits/sec with a 65535 send buffer. We want this to be a multiple + of 1k, but since 64k breaks WSADuplicateSocket we use 63Kb. + (*) Maximum normal TCP window size. Coincidence? */ #ifdef __x86_64__ ((fhandler_socket *) fd)->rmem () = 212992; ((fhandler_socket *) fd)->wmem () = 212992; #else - ((fhandler_socket *) fd)->rmem () = 65535; - ((fhandler_socket *) fd)->wmem () = 65535; + ((fhandler_socket *) fd)->rmem () = 64512; + ((fhandler_socket *) fd)->wmem () = 64512; #endif if (::setsockopt (soc, SOL_SOCKET, SO_RCVBUF, (char *) &((fhandler_socket *) fd)->rmem (), sizeof (int))) |