adjust buff size,same as sing

Makefile

@@ -12,7 +12,7 @@ VERSION=$(shell git rev-parse --short HEAD)
 endif
 
 BUILDTIME=$(shell date -u)
-GOBUILD=CGO_ENABLED=0 go build -tags with_gvisor -trimpath -ldflags '-X "github.com/Dreamacro/clash/constant.Version=$(VERSION)" \
+GOBUILD=CGO_ENABLED=0 go build -tags with_gvisor,with_low_memory -trimpath -ldflags '-X "github.com/Dreamacro/clash/constant.Version=$(VERSION)" \
 		-X "github.com/Dreamacro/clash/constant.BuildTime=$(BUILDTIME)" \
 		-w -s -buildid='
 

common/pool/buffer_low_memory.go

@@ -0,0 +1,15 @@
+//go:build with_low_memory
+
+package pool
+
+const (
+	// io.Copy default buffer size is 32 KiB
+	// but the maximum packet size of vmess/shadowsocks is about 16 KiB
+	// so define a buffer of 20 KiB to reduce the memory of each TCP relay
+	RelayBufferSize = 16 * 1024
+
+	// RelayBufferSize uses 20KiB, but due to the allocator it will actually
+	// request 32Kib. Most UDPs are smaller than the MTU, and the TUN's MTU
+	// set to 9000, so the UDP Buffer size set to 16Kib
+	UDPBufferSize = 8 * 1024
+)

common/pool/buffer_standard.go

@@ -0,0 +1,15 @@
+//go:build !with_low_memory
+
+package pool
+
+const (
+	// io.Copy default buffer size is 32 KiB
+	// but the maximum packet size of vmess/shadowsocks is about 16 KiB
+	// so define a buffer of 20 KiB to reduce the memory of each TCP relay
+	RelayBufferSize = 20 * 1024
+
+	// RelayBufferSize uses 20KiB, but due to the allocator it will actually
+	// request 32Kib. Most UDPs are smaller than the MTU, and the TUN's MTU
+	// set to 9000, so the UDP Buffer size set to 16Kib
+	UDPBufferSize = 16 * 1024
+)

common/pool/pool.go

@@ -1,17 +1,5 @@
 package pool
 
-const (
-	// io.Copy default buffer size is 32 KiB
-	// but the maximum packet size of vmess/shadowsocks is about 16 KiB
-	// so define a buffer of 20 KiB to reduce the memory of each TCP relay
-	RelayBufferSize = 20 * 1024
-
-	// RelayBufferSize uses 20KiB, but due to the allocator it will actually
-	// request 32Kib. Most UDPs are smaller than the MTU, and the TUN's MTU
-	// set to 9000, so the UDP Buffer size set to 16Kib
-	UDPBufferSize = 16 * 1024
-)
-
 func Get(size int) []byte {
 	return defaultAllocator.Get(size)
 }