Introduction 
<p>The performance of four lock routines is measured 
on both mill3, 200MHz Quad PPro, and clump3, 167 Mhz eight-way Sun 
Enterprise.</p>
	
<p>How it Works

<p>A number of threads will insert 500 messages 
(each message is
an array of 8 integers) into a concurrent queue, which can hold about
25 messages. At any point, there is a receiving thread which
constantly pulls out messages from the queue.

<p>The time it takes for each thread to insert a single message
is then averaged out. The details of the locking algorithms can be
found at http://HTTP.CS.Berkeley.EDU/clumps/ipps98.ps </p>
	
<p>Nuts and Bolts

<p>Each test is an average over twenty runs. Tests 
can be categorized in two ways- with or without exponential backoff.
With exponential backoff, the thread will exponentially poll before
attempting to acquire the lock again.</p>

<p>Conclusion

<p>For most of the cases, the figures suggest that 
the performance of the PPro and the Sparc are within 10%.</p>	
	
 
<p>Avg. Time of one insertion cost (
500 mgs of 32 bytes) over 20 runs</p>

<p>Legends:<br>
NumThreads: Number of threads concurrently sending messages. <br>
Posix mutex: solaris pthread mutex</p>

<p>Note: All the figures are in MICRO SECOND.</p>
	     
<p><b>Pentium</b><br>
Tests taken on mill3 (Quad 200MHz Pentiums)</p>

<p>WITHOUT exponential backoff 
<table border="1" cellpadding="2" width="60%">
<tr>
    <td><b>NumThreads</b></td>	
    <td><b>1</b> </td>		
    <td><b>2 </b></td>		
    <td><b>3</b> </td>
</tr>

<tr>
<td>Test & Set</td>
<td>2.467200 </td>	
<td>3.250350 </td>
<td>4.016100 </td>
</tr>

<tr>
<td>Test Test& Set </td>
<td>2.495800 </td>	
<td>3.411050 </td>	
<td>4.595834 </td>
</tr>

<tr>
<td>Ticket </td>
<td>2.484800 </td>
<td>3.204400 </td>
<td>3.735900 </td>
</tr>

<tr>
<td>Posix mutex	</td>
<td>3.601400 </td>
<td>6.648050 </td>
<td>7.410434 </td>
</tr>
</table>

<p>WITH exponential backoff

<table border="1" cellpadding="2" width="60%">
<tr>
<td><b>NumThreads</b></td>	
<td><b>1</b></td>
<td><b>2</b></td>
<td><b>3</b></td>
</tr>

<tr>
<td>Test & Set </td>
<td>2.644300 </td>
<td>2.993100 </td>
<td>3.211567 </td>
</tr>

<tr>
<td>Test Test& Set </td>
<td>2.712000 </td>
<td>3.397550 </td>
<td>3.909367 </td>
</tr>

<tr>
<td>Ticket </td>
<td>2.723600 </td>
<td>3.180550 </td>
<td>5.288367 </td>
</tr>

<tr>
<td>Posix mutex </td>
<td>3.564200 </td>
<td>6.729900 </td>
<td>7.714700 </td>
</tr>
</table>

<p><b>SPARC </b>

<p>Tests taken on clump3 (Eight-way Sun Enterprise 167MHz)</p>
 
<p>WITHOUT exponential backoff
<table border="1" cellpadding="2" width="60%">
<tr>
<td><b>NumThreads </b></td>
<td><b>1 </b></td>
<td><b>2 </b></td>
<td><b>3</b></td>
</tr>

<tr>
<td>Test & Set </td>	
<td>2.639800 </td>
<td>3.398750 </td>
<td>3.522134 </td>
</tr>

<tr>
<td>Test& </td>
<td>2.673200 </td>
<td>3.735400 </td>
<td>3.931433 </td>
</tr>

<tr>
<Td>Ticket </td>
<td>2.819200 </td>
<td>3.962900 </td>
<td>4.095533 </td>
</tr>

<tr>
<td>Posix mutex	</td>
<td>3.697600 </td>
<td>11.443000**	</td>
<td>11.547366 </td>
</tr>
</table>
<br>