Single Core Gen 3 i5 Test, a.k.a. mint Running cpi benchmark n=217483640 with one core Fri Jul 8 15:08:59 EDT 2016 CPU: Dual core Intel Core i5-3340M (-HT-MCP-) cache: 3072 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 10764 clock speeds: min/max: 1200/3400 MHz 1: 1333 MHz 2: 1267 MHz 3: 2025 MHz 4: 1370 MHz Process 0 of 1 is on mint pi is approximately 3.1415926535899121, Error is 0.0000000000001190 wall clock time = 12.475515 Single Core Gen 2 i3 Test, a.k.a Optiplex-790 Running cpi benchmark n=217483640 with one core Fri Jul 8 15:15:06 EDT 2016 CPU: Dual core Intel Core i3-2100 (-HT-MCP-) cache: 3072 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 12371 clock speeds: min/max: 1600/3100 MHz 1: 1626 MHz 2: 1728 MHz 3: 1681 MHz 4: 1694 MHz Process 0 of 1 is on OptiPlex-790 pi is approximately 3.1415926535899121, Error is 0.0000000000001190 wall clock time = 15.307654 Test using MPI to run cpi on both machines Test again with cpi, n=217483640 and increase the cores running one at a time using a script. Ran from the desktop. It is also possible to run it "backwards", meaning run the slave cores first and also only run the program only on the slave machine from the master. Process 0 of 1 is on OptiPlex-790 pi is approximately 3.1415926535898078, Error is 0.0000000000000147 wall clock time = 15.350212 Process 0 of 2 is on OptiPlex-790 Process 1 of 2 is on OptiPlex-790 pi is approximately 3.1415926535899095, Error is 0.0000000000001164 wall clock time = 7.736048 Process 0 of 3 is on OptiPlex-790 Process 1 of 3 is on OptiPlex-790 Process 2 of 3 is on mint pi is approximately 3.1415926535898184, Error is 0.0000000000000253 wall clock time = 5.281412 Process 1 of 4 is on OptiPlex-790 Process 0 of 4 is on OptiPlex-790 Process 2 of 4 is on mint Process 3 of 4 is on mint pi is approximately 3.1415926535898633, Error is 0.0000000000000702 wall clock time = 3.880834 Process 1 of 5 is on OptiPlex-790 Process 0 of 5 is on OptiPlex-790 Process 2 of 5 is on mint Process 3 of 5 is on mint Process 4 of 5 is on mint pi is approximately 3.1415926535898362, Error is 0.0000000000000431 wall clock time = 3.568677 Process 0 of 6 is on OptiPlex-790 Process 1 of 6 is on OptiPlex-790 Process 2 of 6 is on mint Process 3 of 6 is on mint Process 4 of 6 is on mint Process 5 of 6 is on mint pi is approximately 3.1415926535898233, Error is 0.0000000000000302 wall clock time = 3.250462 Adding a 3rd Machine, shows up something interesting... The Dell-System-Inspiron-N7110 is a Gen 2 i5 machine, runs the same speed as the i3 Optiplex, as in both will run at 3.1GHz on a single core that is run hard. The Dell-System-Inspiron-N7110 i5 will go to 2.9GHz if all cores are loaded. I plugged the 2 laptops units into Ethernet to see if it was a bandwidth things and it barely changes the results. It has Mint installed, so I installed MPICH2 right on it, no USB stick used on this one. Starting with 7 processes... Process 0 of 7 is on OptiPlex-790 Process 1 of 7 is on OptiPlex-790 Process 6 of 7 is on Dell-System-Inspiron-N7110 Process 2 of 7 is on mint Process 3 of 7 is on mint Process 4 of 7 is on mint Process 5 of 7 is on mint pi is approximately 3.1415926535897758, Error is 0.0000000000000173 wall clock time = 2.745917 Process 0 of 8 is on OptiPlex-790 Process 1 of 8 is on OptiPlex-790 Process 6 of 8 is on Dell-System-Inspiron-N7110 Process 7 of 8 is on Dell-System-Inspiron-N7110 Process 2 of 8 is on mint Process 3 of 8 is on mint Process 4 of 8 is on mint Process 5 of 8 is on mint pi is approximately 3.1415926535897696, Error is 0.0000000000000235 wall clock time = 2.370080 Process 0 of 9 is on OptiPlex-790 Process 6 of 9 is on Dell-System-Inspiron-N7110 Process 1 of 9 is on OptiPlex-790 Process 7 of 9 is on Dell-System-Inspiron-N7110 Process 8 of 9 is on Dell-System-Inspiron-N7110 Process 2 of 9 is on mint Process 3 of 9 is on mint Process 4 of 9 is on mint Process 5 of 9 is on mint pi is approximately 3.1415926535897762, Error is 0.0000000000000169 wall clock time = 3.106747 Process 0 of 10 is on OptiPlex-790 Process 1 of 10 is on OptiPlex-790 Process 2 of 10 is on mint Process 3 of 10 is on mint Process 4 of 10 is on mint Process 5 of 10 is on mint Process 6 of 10 is on Dell-System-Inspiron-N7110 Process 7 of 10 is on Dell-System-Inspiron-N7110 Process 8 of 10 is on Dell-System-Inspiron-N7110 Process 9 of 10 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898322, Error is 0.0000000000000391 wall clock time = 3.282801 Optiplex-790 + Dell-System-Inspiron-N7110 combo The Optiplex-790 + Dell-System-Inspiron-N7110 combo and the results are not nearly as good as the combo above. Sure the Gen 3 i5 is a tad faster than the Gen2, but the results are worse than that difference. Process 0 of 1 is on OptiPlex-790 pi is approximately 3.1415926535898078, Error is 0.0000000000000147 wall clock time = 15.370562 Process 0 of 2 is on OptiPlex-790 Process 1 of 2 is on OptiPlex-790 pi is approximately 3.1415926535899095, Error is 0.0000000000001164 wall clock time = 7.703016 Process 0 of 3 is on OptiPlex-790 Process 1 of 3 is on OptiPlex-790 Process 2 of 3 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898184, Error is 0.0000000000000253 wall clock time = 9.985078 Process 1 of 4 is on OptiPlex-790 Process 0 of 4 is on OptiPlex-790 Process 2 of 4 is on Dell-System-Inspiron-N7110 Process 3 of 4 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898633, Error is 0.0000000000000702 wall clock time = 4.123178 Process 0 of 5 is on OptiPlex-790 Process 1 of 5 is on OptiPlex-790 Process 2 of 5 is on Dell-System-Inspiron-N7110 Process 3 of 5 is on Dell-System-Inspiron-N7110 Process 4 of 5 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898362, Error is 0.0000000000000431 wall clock time = 5.847727 Process 0 of 6 is on OptiPlex-790 Process 1 of 6 is on OptiPlex-790 Process 2 of 6 is on Dell-System-Inspiron-N7110 Process 3 of 6 is on Dell-System-Inspiron-N7110 Process 4 of 6 is on Dell-System-Inspiron-N7110 Process 5 of 6 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898233, Error is 0.0000000000000302 wall clock time = 5.492374 Running the test "Backwards" shows something strage with the Dell-System-Inspiron-N7110, slowing down with the 3rd core added, behavior I did not see with the i3 machine. Process 0 of 1 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898078, Error is 0.0000000000000147 wall clock time = 15.777697 Process 0 of 2 is on Dell-System-Inspiron-N7110 Process 1 of 2 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535899095, Error is 0.0000000000001164 wall clock time = 8.232763 Process 1 of 3 is on Dell-System-Inspiron-N7110 Process 2 of 3 is on Dell-System-Inspiron-N7110 Process 0 of 3 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898189, Error is 0.0000000000000258 wall clock time = 8.707151 Process 0 of 4 is on Dell-System-Inspiron-N7110 Process 1 of 4 is on Dell-System-Inspiron-N7110 Process 2 of 4 is on Dell-System-Inspiron-N7110 Process 3 of 4 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898633, Error is 0.0000000000000702 wall clock time = 8.181242 Process 4 of 5 is on OptiPlex-790 Process 0 of 5 is on Dell-System-Inspiron-N7110 Process 1 of 5 is on Dell-System-Inspiron-N7110 Process 2 of 5 is on Dell-System-Inspiron-N7110 Process 3 of 5 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898362, Error is 0.0000000000000431 wall clock time = 6.594121 Process 4 of 6 is on OptiPlex-790 Process 5 of 6 is on OptiPlex-790 Process 0 of 6 is on Dell-System-Inspiron-N7110 Process 1 of 6 is on Dell-System-Inspiron-N7110 Process 2 of 6 is on Dell-System-Inspiron-N7110 Process 3 of 6 is on Dell-System-Inspiron-N7110 pi is approximately 3.1415926535898233, Error is 0.0000000000000302 wall clock time = 5.460058 Dell-System-Inspiron-N7110 booted off of the Mint USB stick, shows the same behavior when 3rd core comes on. Mon Jul 18 16:20:50 EDT 2016 Process 0 of 1 is on OptiPlex-790 pi is approximately 3.1415926535898078, Error is 0.0000000000000147 wall clock time = 15.409897 Process 0 of 2 is on OptiPlex-790 Process 1 of 2 is on OptiPlex-790 pi is approximately 3.1415926535899095, Error is 0.0000000000001164 wall clock time = 8.541379 Process 0 of 3 is on OptiPlex-790 Process 1 of 3 is on OptiPlex-790 Process 2 of 3 is on mint pi is approximately 3.1415926535898184, Error is 0.0000000000000253 wall clock time = 5.174366 Process 0 of 4 is on OptiPlex-790 Process 1 of 4 is on OptiPlex-790 Process 2 of 4 is on mint Process 3 of 4 is on mint pi is approximately 3.1415926535898633, Error is 0.0000000000000702 wall clock time = 4.114069 Process 0 of 5 is on OptiPlex-790 Process 1 of 5 is on OptiPlex-790 Process 2 of 5 is on mint Process 3 of 5 is on mint Process 4 of 5 is on mint pi is approximately 3.1415926535898362, Error is 0.0000000000000431 wall clock time = 6.289006 Process 0 of 6 is on OptiPlex-790 Process 1 of 6 is on OptiPlex-790 Process 2 of 6 is on mint Process 3 of 6 is on mint Process 4 of 6 is on mint Process 5 of 6 is on mint pi is approximately 3.1415926535898233, Error is 0.0000000000000302 wall clock time = 5.462565 Reverse- Running mint cores first, shows time go up when 3rd core runs. Mon Jul 18 16:23:49 EDT 2016 Process 0 of 1 is on mint pi is approximately 3.1415926535898078, Error is 0.0000000000000147 wall clock time = 15.448086 Process 0 of 2 is on mint Process 1 of 2 is on mint pi is approximately 3.1415926535899095, Error is 0.0000000000001164 wall clock time = 8.257367 Process 0 of 3 is on mint Process 1 of 3 is on mint Process 2 of 3 is on mint pi is approximately 3.1415926535898189, Error is 0.0000000000000258 wall clock time = 9.028470 Process 0 of 4 is on mint Process 1 of 4 is on mint Process 2 of 4 is on mint Process 3 of 4 is on mint pi is approximately 3.1415926535898633, Error is 0.0000000000000702 wall clock time = 8.182938 Process 4 of 5 is on OptiPlex-790 Process 0 of 5 is on mint Process 1 of 5 is on mint Process 2 of 5 is on mint Process 3 of 5 is on mint pi is approximately 3.1415926535898362, Error is 0.0000000000000431 wall clock time = 6.554721 Process 4 of 6 is on OptiPlex-790 Process 5 of 6 is on OptiPlex-790 Process 0 of 6 is on mint Process 1 of 6 is on mint Process 2 of 6 is on mint Process 3 of 6 is on mint pi is approximately 3.1415926535898233, Error is 0.0000000000000302 wall clock time = 5.465303 Testing with n set to 2^31-1 will make the cpi program run indefinately. Running all 4 cores on the Dell-System-Inspiron-N7110 shows them all running at OK speeds. CPU: Dual core Intel Core i5-2450M (-HT-MCP-) cache: 3072 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 9967 clock speeds: min/max: 800/3100 MHz 1: 2899 MHz 2: 2899 MHz 3: 2899 MHz 4: 2900 MHz