title: Why is buffered I/O faster than unbuffered I/O
body: <p>While reading  <a href="https://stackoverflow.com/questions/5112992/why-is-buffering-in-c-important">this</a>, I found a reasonable answer, which says:  </p>
  
  <blockquote>
    <p>Case 1: Directly Writing to File On Disk</p>
  
  <pre><code>100 times x 1 ms = 100 ms
  </code></pre>
  </blockquote>
  
  <p>I understood that.   Next, </p>
  
  <blockquote>
    <p>Case 3: Buffering in Memory before Writing to File on Disk</p>
  
  <pre><code>(100 times x 0.5 ms) + 1 ms = 51 ms
  </code></pre>
  </blockquote>
  
  <p>I didn't understand the 1 ms. What is the difference in between writing 100 data to disk and writing 1 data to disk? Why do both of them cost 1 ms?</p>