Date: Sun, 25 Mar 2012 03:34:08 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: bcrypt: actual performance versus benchmark RB, all - This is actually a john-users topic, not john-dev. (Yes, I should have pointed this out when I said that it should be a separate thread.) I'll reply in here for now, but overall let's be using john-users more. john-dev is for discussing JtR source code (and proposed changes to it) - stuff that would be too technical and uninteresting for JtR users. On Sat, Mar 24, 2012 at 10:03:18AM -0600, RB wrote: > On Fri, Mar 23, 2012 at 18:54, Solar Designer <solar@...nwall.com> wrote: > > Are you saying that benchmark gives you 2k c/s, but actual run only > > 100 c/s? Is that for bcrypt or for RAR? Anyway, this is best discussed > > on its own thread. > > Yes, for hashes beginning with "$2$" harvested from a SuSE Enterprise > Linux system I was analyzing. > > On my W3565, which shows best JtR performance with 4 threads > (OMP_NUM_THREADS=4), and using the magnum-jumbo git repo updated > 2012/03/21, "./john --test=20 --format=bf" benchmarked at between 2k > and 2.1k c/s. > > When cracking a single hash, actual speeds experienced were between 50 > and 100 (occasionally reaching up to 110) c/s on a system with no > other load. This was on a system running gentoo-sources-3.3.0, > glibc-2.14.1, and gcc-4.6.2 (~x86_64 fully updated). John's benchmark for --format=bf assumes 32 iterations ("$2a$05" hash encoding prefix), whereas actual modern systems use higher iteration counts. From your numbers, it appears that your actual password hash used something like 1024 iterations ("$2a$10" prefix). If so, what you're observing is the correct behavior. As to OMP_NUM_THREADS=4, try to tune GOMP_SPINCOUNT instead (try values like 10000 and 2000000; gcc 4.6.x's default is 300000) while keeping the thread count at its default (should be 8 for your CPU, right?) You'll likely achieve higher speed in this way (should be over 3k c/s on the benchmark). And indeed you should be using an -x86-64 (or -x86-64i if jumbo) build of John (not -x86-sse2 or other 32-bit). Alexander
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