From: Jens Axboe <axboe@fb.com>
Date: Thu, 9 Oct 2014 18:05:44 +0000 (-0600)
Subject: engines/net: add TCP_MAXSEG setting (mss)
X-Git-Tag: fio-2.1.14~79
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=e5f34d95af9163b42945e1737f628a9526a6f83c

engines/net: add TCP_MAXSEG setting (mss)

Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/HOWTO b/HOWTO
index f78e47c1..d2ce4d8e 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1687,6 +1687,8 @@ that defines them is selected.
 
 [net] window_size	Set the desired socket buffer size for the connection.
 
+[net] mss	Set the TCP maximum segment size (TCP_MAXSEG).
+
 [e4defrag] donorname=str
 	        File will be used as a block donor(swap extents between files)
 [e4defrag] inplace=int
diff --git a/configure b/configure
index 3e3c9785..81b16a35 100755
--- a/configure
+++ b/configure
@@ -1093,6 +1093,26 @@ if compile_prog "" "" "SO_SNDBUF"; then
 fi
 echo "Net engine window_size        $window_size"
 
+##########################################
+# Check whether we have TCP_MAXSEG
+mss="no"
+cat > $TMPC << EOF
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+int main(int argc, char **argv)
+{
+  return setsockopt(0, IPPROTO_TCP, TCP_MAXSEG, NULL, 0);
+}
+EOF
+if compile_prog "" "" "TCP_MAXSEG"; then
+  mss="yes"
+fi
+echo "TCP_MAXSEG                    $mss"
+
 ##########################################
 # Check whether we have RLIMIT_MEMLOCK
 rlimit_memlock="no"
@@ -1451,6 +1471,9 @@ fi
 if test "$window_size" = "yes" ; then
   output_sym "CONFIG_NET_WINDOWSIZE"
 fi
+if test "$mss" = "yes" ; then
+  output_sym "CONFIG_NET_MSS"
+fi
 if test "$rlimit_memlock" = "yes" ; then
   output_sym "CONFIG_RLIMIT_MEMLOCK"
 fi
diff --git a/engines/net.c b/engines/net.c
index ac5a93c8..9a327da8 100644
--- a/engines/net.c
+++ b/engines/net.c
@@ -40,6 +40,7 @@ struct netio_options {
 	unsigned int nodelay;
 	unsigned int ttl;
 	unsigned int window_size;
+	unsigned int mss;
 	char *intfc;
 };
 
@@ -177,6 +178,18 @@ static struct fio_option options[] = {
 		.category = FIO_OPT_C_ENGINE,
 		.group	= FIO_OPT_G_NETIO,
 	},
+#endif
+#ifdef CONFIG_NET_MSS
+	{
+		.name	= "mss",
+		.lname	= "Maximum segment size",
+		.type	= FIO_OPT_INT,
+		.off1	= offsetof(struct netio_options, mss),
+		.minval	= 0,
+		.help	= "Set TCP maximum segment size",
+		.category = FIO_OPT_C_ENGINE,
+		.group	= FIO_OPT_G_NETIO,
+	},
 #endif
 	{
 		.name	= NULL,
@@ -233,6 +246,30 @@ static int set_window_size(struct thread_data *td, int fd)
 #endif
 }
 
+static int set_mss(struct thread_data *td, int fd)
+{
+#ifdef CONFIG_NET_MSS
+	struct netio_options *o = td->eo;
+	unsigned int mss;
+	int ret;
+
+	if (!o->mss || !is_tcp(o))
+		return 0;
+
+	mss = o->mss;
+	ret = setsockopt(fd, IPPROTO_TCP, TCP_MAXSEG, (void *) &mss,
+				sizeof(mss));
+	if (ret < 0)
+		td_verror(td, errno, "setsockopt TCP_MAXSEG");
+
+	return ret;
+#else
+	td_verror(td, -EINVAL, "setsockopt TCP_MAXSEG");
+	return -1;
+#endif
+}
+
+
 /*
  * Return -1 for error and 'nr events' for a positive number
  * of events
@@ -655,6 +692,10 @@ static int fio_netio_connect(struct thread_data *td, struct fio_file *f)
 		close(f->fd);
 		return 1;
 	}
+	if (set_mss(td, f->fd)) {
+		close(f->fd);
+		return 1;
+	}
 
 	if (is_udp(o)) {
 		if (!fio_netio_is_multicast(td->o.filename))
@@ -1101,6 +1142,10 @@ static int fio_netio_setup_listen_inet(struct thread_data *td, short port)
 		close(fd);
 		return 1;
 	}
+	if (set_mss(td, fd)) {
+		close(fd);
+		return 1;
+	}
 
 	if (td->o.filename) {
 		if (!is_udp(o) || !fio_netio_is_multicast(td->o.filename)) {
diff --git a/fio.1 b/fio.1
index dc727d36..9ddf101a 100644
--- a/fio.1
+++ b/fio.1
@@ -1528,6 +1528,9 @@ reader when multiple readers are listening to the same address.
 .BI (net, window_size) \fR=\fPint
 Set the desired socket buffer size for the connection.
 .TP
+.BI (net, mss) \fR=\fPint
+Set the TCP maximum segment size (TCP_MAXSEG).
+.TP
 .BI (e4defrag,donorname) \fR=\fPstr
 File will be used as a block donor (swap extents between files)
 .TP