transport: when using write buffer pooling, use input size instead of size*2 (#6983)

dialoptions.go

@@ -154,9 +154,7 @@ func WithSharedWriteBuffer(val bool) DialOption {
 }
 
 // WithWriteBufferSize determines how much data can be batched before doing a
-// write on the wire. The corresponding memory allocation for this buffer will
+// write on the wire. The default value for this buffer is 32KB.
-// be twice the size to keep syscalls low. The default value for this buffer is
-// 32KB.
 //
 // Zero or negative values will disable the write buffer such that each write
 // will be on underlying connection. Note: A Send call may not directly

internal/transport/http_util.go

@@ -418,10 +418,9 @@ func newFramer(conn net.Conn, writeBufferSize, readBufferSize int, sharedWriteBu
 	return f
 }
 
-func getWriteBufferPool(writeBufferSize int) *sync.Pool {
+func getWriteBufferPool(size int) *sync.Pool {
 	writeBufferMutex.Lock()
 	defer writeBufferMutex.Unlock()
-	size := writeBufferSize * 2
 	pool, ok := writeBufferPoolMap[size]
 	if ok {
 		return pool

server.go

@@ -249,11 +249,9 @@ func SharedWriteBuffer(val bool) ServerOption {
 }
 
 // WriteBufferSize determines how much data can be batched before doing a write
-// on the wire. The corresponding memory allocation for this buffer will be
+// on the wire. The default value for this buffer is 32KB. Zero or negative
-// twice the size to keep syscalls low. The default value for this buffer is
+// values will disable the write buffer such that each write will be on underlying
-// 32KB. Zero or negative values will disable the write buffer such that each
+// connection. Note: A Send call may not directly translate to a write.
-// write will be on underlying connection.
-// Note: A Send call may not directly translate to a write.
 func WriteBufferSize(s int) ServerOption {
 	return newFuncServerOption(func(o *serverOptions) {
 		o.writeBufferSize = s