<pre>Brian, I've run gmpbench on my (32-bit, single-core) Ubuntu machine... jdo@BlackAdder:~/gmpbench-0.1$ cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 6 model : 10 model name : AMD Athlon(tm) XP 2800+ stepping : 0 cpu MHz : 2255.147 cache size : 512 KB ...and this gives the following divide results: Program divide divide 8192 32 GMPbench.base.divide.8192,32 result: 506617 divide 8192 64 GMPbench.base.divide.8192,64 result: 148316 divide 8192 128 GMPbench.base.divide.8192,128 result: 94882 divide 8192 4096 GMPbench.base.divide.8192,4096 result: 32560 divide 8192 8064 GMPbench.base.divide.8192,8064 result: 430080 divide 131072 8192 GMPbench.base.divide.131072,8192 result: 677 divide 131072 65536 GMPbench.base.divide.131072,65536 result: 373 divide 8388608 4194304 GMPbench.base.divide.8388608,4194304 result: 1.07 GMPbench.base.divide result: 8489.3 You might notice several things: 1) The results of your only slightly higher clocked X2 are generally 2 to 3 times better than mine... 2) ...except for the FIRST result. It looks like the divide.8192,32 and divide.8192,64 algorithms really do not differ much on a 64-bit machine (probably because the divider is stored in a 64-bit "word" anyway). For my (32-bit) machine this does matter, as a 64-bit divider is stored in 2 32-bits "words". In short, for a 64-bit machine, the first test should probably be excluded (or at least not taken into account when calculating the final benchmark result). CU, JDO --------------------------------- Original mail --------------------------------- I have been running gmpbench on an 2.4 GHz AMD64 X2 machine with the following summary results: Running benchmarks Category base Program multiply GMPbench.base.multiply result: 47916 Program divide GMPbench.base.divide result: 18006 GMPbench.base result: 29373 Program rsa GMPbench.app result: 2386.3 GMPbench result: 8372 The striking feature here is that the divide results are poor and I am wondering why this is. Program divide divide 8192 32 GMPbench.base.divide.8192,32 result: 356495 divide 8192 64 GMPbench.base.divide.8192,64 result: 336958 divide 8192 128 GMPbench.base.divide.8192,128 result: 170276 divide 8192 4096 GMPbench.base.divide.8192,4096 result: 88660 divide 8192 8064 GMPbench.base.divide.8192,8064 result: 953276 divide 131072 8192 GMPbench.base.divide.131072,8192 result: 2170 divide 131072 65536 GMPbench.base.divide.131072,65536 result: 1202 divide 8388608 4194304 GMPbench.base.divide.8388608,4194304 result: 2.45 GMPbench.base.divide result: 18006 Given these results for divide, is it likely that the limits for switching algorithms is wrong? Or do I need to do more work on assembler code in support of divide operations? Any observations would be appreciated. Brian Gladman</pre> <div> </div> -- <div> Enter the Bourne Ultimatum Sweepstakes <a href="http://www.hollywoodlife.net/index.php/sweepstakescontests/the-bourne-ultimatum/?utm_source=mail_hl_sent_footer&utm_medium=email&utm_term=070713&utm_content=hl_textlink&utm_campaign=the-bourne-ultimatum" target="_blank">View Trailer, Win Free Prizes.</a> In Theaters 08.03.07</div>