ftw@fftw.org</a>.
</p>
<p>If a cycle counter is not available on your system (e.g. some embedded
processor), and you don&rsquo;t want to use estimated plans, as a last resort
you can use the <code>--with-slow-timer</code> option to <code>configure</code> (on
Unix) or <code>#define WITH_SLOW_TIMER</code> in <code>config.h</code> (elsewhere).
This will use the much lower-resolution <code>gettimeofday</code> function, or even
<code>clock</code> if the former is unavailable, and planning will be
extremely slow.