android - How to set proper buffersize of AudioRecord

Question

I use AudioRecord to record audio on Android device. To create a instance of AudioRecord, you should set a fixed size of buffer to store the audio data. Then, we need pull data from this buffer continuously. If the size of buffer is too small and fetching data is too slow, the buffer will be overflow !
To avoid this exception, I want to set the size of buffer larger as far as possible and fetching data in time.
AudioRecord provides the getMinBufferSize(int,int,int) method to get a min size of buffer that audio hardware can support. But this is mininum size not the proper size of buffer.

My question is how to calculate and set the proper size of the buffer?

Here is what I using the AudioRecord:

audioRecord = new AudioRecord(audio_source, sampleRate, audio_channel, audio_encoding, buffer_size);
new Thread(new Runnable{
    while(true){ //Loop start
        readSize = audioRecorder.read(readBuffer, 0, useReadBufferSize); // fetch data from  buffer to readbuffer
        // throw readbuffer data out, do this operation as qucik as possible, Avoid to block thread
        // check if the AudioRecord stopped and break if true
    }
}).start();