What is automatic flushing in MATLAB's fopen function?

Question

In fopen properties we can set 'W' and 'A' for without automatic flushing option. What is difference between these and using automatic flushing (default option)?

Answer 1

When automatic flushing is on, matlab will effectively write to disk after any call to fwrite even if writing very small chunk of data.

When disabling automatic flushing, matlab only writes to internal memory buffer and flushes everything to disk only when calling fclose (or when buffer is full). This may improve performances as less access to disk are required for writing operations.