When you have a powerful processor such as the AMD Phenom, you really want to use the full fucking force of that thing. It’s kind of like keeping a Ferrari in the garage the whole year if you don’t.
So i figured, how much difference would it make, if you benchmarked one core (out of four), versus the full four cores. I ran some tests using John The Ripper, which should be fairly good at loading the processor, as it’s mostly just grunt-work. I added on the MPI patch, which allows you to use the mpich2 framework to run John on multiple processors/threads and even on a cluster of machines over the network.
The result on one core was i think 4400 raw MD5 hashes per second (correct me if i’m wrong here), where as on all four cores, using 8 threads, the result was an impressing 27400 hashes per second. I have no idea how it technically works, but i can say from the ./john –test benchmark mode that it was indeed faster.
Comparing to an older machine, Agamemnon, which was two 3.0 Ghz Xeon’s (the first 64 bit ones i think), the result on both cores, 4 threads, was ~11 000 hashes per second.
It was nice seeing all four cores at 100% load for the duration of the test. Normally, just one is used, and the others do “something”, between 0-20% in load, while one core is used more fully.
To run john the ripper like this, i did the following (i’ll document this here, because MPI’s site didn’t have all that good a documentation):
- Use your favorite package-manager to download at least OpenSSL, and the mpich libraries (do a search, and get the ones listed -dev), or download and compile if you do it that way
- Download and compile john the ripper, with all necessary patches (such as the MPI and Jumbo-patch). Be sure to use the machine-type as correctly as possible when you issue make, e.g. make clean linux-x86-64, for a 64 bit version. Issuing the make command alone will give you a list of the supported architechtures.
- Download and compile the mpich2 set. Download any dependencies, should you need them.
- After this, create in your home directory the file .mpd.conf, and chmod it to 600.
- Start mpd using mpd &
- Go to the run directory under the John main directory, and issue for instance mpiexec -n 8 ./john –test . This will run the benchmark mode of John the Ripper, using the mpiexec plaform, and running 8 processes. Depending on your processor, you may want to change this number.