optimize: improve performance on log disabled (#3916)

core/logx/logs_test.go

@@ -666,6 +666,7 @@ func TestDisable(t *testing.T) {
 	WithMaxSize(1024)(&opt)
 	assert.Nil(t, Close())
 	assert.Nil(t, Close())
+	assert.Equal(t, uint32(disableLevel), atomic.LoadUint32(&logLevel))
 }
 
 func TestDisableStat(t *testing.T) {
@@ -680,7 +681,7 @@ func TestDisableStat(t *testing.T) {
 }
 
 func TestSetWriter(t *testing.T) {
-	atomic.StoreUint32(&disableLog, 0)
+	atomic.StoreUint32(&logLevel, 0)
 	Reset()
 	SetWriter(nopWriter{})
 	assert.NotNil(t, writer.Load())