<span class="ul-threaded" style="margin: 0.5em 0pt 0pt -15px;"><span class="connect"><span id="li2846012" class="li-threaded"><span class="threaded"><span class="post-middle"><span id="post2846012" style="display: block;"><span>we have two ways to get time :statistic(<b class="highlight">runtime</b>) and statistic(wall_clock).I have not find any exact desciption about the two methods. 
</span><br><span>Some one have guessed:"Since erlang is not
</span><br><span>guaranteed to have 100% of your CPU time, <b class="highlight">runtime</b> would be the actual amount
</span><br><span>of processing time used by erlang. "wall_clock" time is simply recording the
</span><br><span>actual time the process started and the actual time the process ended and
</span><br><span>giving you the difference in "real time" ."
</span><br><br><span>So we can came to the conclusion that <b class="highlight">runtime</b> is less than  wall_clock.I did some experiments to verify this,the result is really wired that I can't understand:  <b class="highlight">runtime</b> is probably both more or less than  wall_clock! Waht's happenging? Would some one explain this?
</span><br><span>process spawn average time =<b class="highlight">runtime</b> <wall_clock> us
</span><br><span>process spawn average time =1.5 <3.2> us
</span><br><span>process spawn average time =3.44 <2.5> us
<br><br>just wondering how to get the exact time that my process needed……<br clear="all"></span></span></span></span></span></span></span><br>-- <br>************************************************<br>Gu Junli--ȿ<br>PHD Candidate of Tsinghua University<br>
Beijing 100084,China<br>Tel: 86-10-62795139<br><br>************************************************<br>