Bump SO_SNDBUF for fdbased endpoint used by runsc.

Updates #231

PiperOrigin-RevId: 289897881

2 files changed, 21 insertions, 16 deletions

diff --git a/benchmarks/tcp/tcp_proxy.go b/benchmarks/tcp/tcp_proxy.go
index dc96add66..72ada5700 100644
--- a/benchmarks/tcp/tcp_proxy.go
+++ b/benchmarks/tcp/tcp_proxy.go
@@ -84,8 +84,8 @@ func (netImpl) printStats() {
 }
 
 const (
-	nicID      = 1       // Fixed.
-	rcvBufSize = 4 << 20 // 1MB.
+	nicID   = 1       // Fixed.
+	bufSize = 4 << 20 // 4MB.
 )
 
 type netstackImpl struct {
@@ -125,13 +125,13 @@ func setupNetwork(ifaceName string, numChannels int) (fds []int, err error) {
 			}
 
 			// RAW Sockets by default have a very small SO_RCVBUF of 256KB,
-			// up it to at least 1MB to reduce packet drops.
-			if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_RCVBUF, rcvBufSize); err != nil {
-				return nil, fmt.Errorf("setsockopt(..., SO_RCVBUF, %v,..) = %v", rcvBufSize, err)
+			// up it to at least 4MB to reduce packet drops.
+			if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_RCVBUF, bufSize); err != nil {
+				return nil, fmt.Errorf("setsockopt(..., SO_RCVBUF, %v,..) = %v", bufSize, err)
 			}
 
-			if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_SNDBUF, rcvBufSize); err != nil {
-				return nil, fmt.Errorf("setsockopt(..., SO_RCVBUF, %v,..) = %v", rcvBufSize, err)
+			if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_SNDBUF, bufSize); err != nil {
+				return nil, fmt.Errorf("setsockopt(..., SO_SNDBUF, %v,..) = %v", bufSize, err)
 			}
 
 			if !*swgso && *gso != 0 {
diff --git a/runsc/sandbox/network.go b/runsc/sandbox/network.go
index be8b72b3e..ff48f5646 100644
--- a/runsc/sandbox/network.go
+++ b/runsc/sandbox/network.go
@@ -321,16 +321,21 @@ func createSocket(iface net.Interface, ifaceLink netlink.Link, enableGSO bool) (
 		}
 	}
 
-	// Use SO_RCVBUFFORCE because on linux the receive buffer for an
-	// AF_PACKET socket is capped by "net.core.rmem_max". rmem_max
-	// defaults to a unusually low value of 208KB. This is too low
-	// for gVisor to be able to receive packets at high throughputs
-	// without incurring packet drops.
-	const rcvBufSize = 4 << 20 // 4MB.
-
-	if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_RCVBUFFORCE, rcvBufSize); err != nil {
-		return nil, fmt.Errorf("failed to increase socket rcv buffer to %d: %v", rcvBufSize, err)
+	// Use SO_RCVBUFFORCE/SO_SNDBUFFORCE because on linux the receive/send buffer
+	// for an AF_PACKET socket is capped by "net.core.rmem_max/wmem_max".
+	// wmem_max/rmem_max default to a unusually low value of 208KB. This is too low
+	// for gVisor to be able to receive packets at high throughputs without
+	// incurring packet drops.
+	const bufSize = 4 << 20 // 4MB.
+
+	if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_RCVBUFFORCE, bufSize); err != nil {
+		return nil, fmt.Errorf("failed to increase socket rcv buffer to %d: %v", bufSize, err)
 	}
+
+	if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_SNDBUFFORCE, bufSize); err != nil {
+		return nil, fmt.Errorf("failed to increase socket snd buffer to %d: %v", bufSize, err)
+	}
+
 	return &socketEntry{deviceFile, gsoMaxSize}, nil
 }