john-users - Is JTR MPIrun can be optimized for more cores ?

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Date: Tue, 9 Mar 2010 20:50:29 +0100
From: "websiteaccess@...il.com" <websiteaccess@...il.com>
To: john-users@...ts.openwall.com
Subject: Is JTR MPIrun can be optimized for more cores ?

Hi

 I have a Mac os X (latest OS) with a 4 core (8 virtually) I7 Core 2.8 
Ghz.

I tested JTR MPI 10 with -incremental mode (compiled SSE2).

 I ran JTR with a 2 millions hashes list, with my own .chr (can crack 
up to 10 letters/digits/some symbols)

Here it is 3 tests (same hashes list, all identical except cores 
numbers, duration for each test 5 minutes): 

1)  mpirun -np 2 ./john -format=raw-md5 -i:alpha10 -pot=2millions.pot 
2millions.txt
  -> crack 5665 hashes

  (After this test 2millions.pot was deleted of course)

2) mpirun -np 4 ./john -format=raw-md5 -i:alpha10 -pot=2millions.pot 
2millions.txt
 -> crack 6591 hashes

 (After this test 2millions.pot was deleted of course)

3) mpirun -np 8 ./john -format=raw-md5 -i:alpha10 -pot=2millions.pot 
2millions.txt
 -> crack 7223 hashes


 Why I get only 1558 more hashes cracked with 8 cores than 2 cores ???

 Is it possible to optimise MPIrun to work better with 4 cores and much 
much better with 8 cores ? 
 Otherwise, why use 8 cores if I get only few hashes cracked more ?

 Thanks,

 W.A.