title: Is there an efficiency hit for a constant formula in a C #define?
body: <p>I was perusing some kernel source code from <code>cpufreq_governor.h</code> and saw this: </p>
  
  <pre><code>/*
   * The polling frequency depends on the capability of the processor. Default
   * polling frequency is 1000 times the transition latency of the processor. The
   * governor will work on any processor with transition latency &lt;= 10ms, using
   * appropriate sampling rate.
   *
   * For CPUs with transition latency &gt; 10ms (mostly drivers with CPUFREQ_ETERNAL)
   * this governor will not work. All times here are in us (micro seconds).
   */
  #define MIN_SAMPLING_RATE_RATIO         (2)
  #define LATENCY_MULTIPLIER          (1000)
  #define MIN_LATENCY_MULTIPLIER          (20)
  #define TRANSITION_LATENCY_LIMIT        (10 * 1000 * 1000)
  </code></pre>
  
  <p>Would it not be more efficient to change the last line to read:</p>
  
  <pre><code>#define TRANSITION_LATENCY_LIMIT        (10000000) /* (10 * 1000 * 1000) */
  </code></pre>