add table

CSC/ex4.html

@@ -99,7 +99,7 @@ <h1>Exercise 4: Practice tuning a small application</h1>
 There are some hints at the bottom.
 
 <P>
-I suggest you start by looking afor evidence of where the program is spending unnecessary time. 
+I suggest you start by looking for evidence of where the program is spending unnecessary time. 
 See if you can improve those places first.  
 There are some obvious hot spots that will help you make progress.
 <P>
@@ -114,15 +114,25 @@ <h1>Exercise 4: Practice tuning a small application</h1>
 How much longer should that take?  How should finding the median scale with number of samples?  Is that 
 what you observe? If not, can you find and fix the problem?
 
+<p>
+On Bob's laptop, the original program scales like:
+<table border="1">
+<tr><th>Run</th><th>CPU sec</th</tr>
+<tr><td>time ./run 500 501</td><td>4.6</td></tr>
+<tr><td>time ./run 500 101</td><td>16.5</td></tr>
+<tr><td>time ./run 500 2001</td><td>63.3</td></tr>
+<tr><td>time ./run 500 3001</td><td>145.0</td></tr>
+<tr><td>time ./run 500 4001</td><td>260.9</td></tr>
+</table>
 <P> 
-To add some interest, we provide some historical idea of how far students at previous CSCs have
+Students at previous CSCs have
 managed to push the performance:
 <UL>
 <li>If "time ./run 500 1001" with the original code takes about 20 seconds or so
 <li>then "time ./run 500 100001", our goal, takes way too long to wait for with the original code.
 <li>Basic profiling work should get you to about 120-135 seconds for the "time ./run 500 100001" goal
 <li>Under 100 seconds requires care, but is possible
-<li>Under 40 seconds has been done
+<li>Under 40 seconds has been done but requires extraordinary effort. Is that worth it?
 </UL>
 
 Note that these are with one specific laptop: Since you're using your own laptop,