This was done because Linus saw that some of the things they were doing for SMP helped in single-processor scheduling as well.  As soon as the SMP code matured to the point that it imposed no penalty on single-processor systems, there was no reason to leave it out.
<br><br><div><span class="gmail_quote">On 11/30/06, <b class="gmail_sendername">Jonathan Hutchins</b> &lt;<a href="mailto:hutchins@tarcanfel.org">hutchins@tarcanfel.org</a>&gt; wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>SMP's been merged into the main kernel.&nbsp;&nbsp;I was hunting for the smp version <br></blockquote></div><br>