Date: Mon, 22 Jun 2015 22:43:11 +0300 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: bcrypt-opencl local vs. private memory On Mon, Jun 22, 2015 at 09:20:51PM +0200, magnum wrote: > Using private: > Device 0: GeForce GTX TITAN X > Local worksize (LWS) 8, Global worksize (GWS) 2048 > Benchmarking: bcrypt-opencl ("$2a$05", 32 iterations) [Blowfish > OpenCL]... DONE > Speed for cost 1 (iteration count) of 32 > Raw: 790 c/s real, 787 c/s virtual > > Using local: > Device 0: GeForce GTX TITAN X > Local worksize (LWS) 8, Global worksize (GWS) 4096 > Benchmarking: bcrypt-opencl ("$2a$05", 32 iterations) [Blowfish > OpenCL]... DONE > Speed for cost 1 (iteration count) of 32 > Raw: 5354 c/s real, 5319 c/s virtual > > BTW I tested oclHashcat too and it does 11570 c/s, we don't even do half > of that :-/ Apparently, hashcat (the CUDA one?) is even faster on TITAN X, giving 14440 c/s at stock clocks, 16890 c/s at +225 MHz o/c: https://gist.github.com/epixoip?direction=desc&sort=updated http://permalink.gmane.org/gmane.comp.security.phc/2988 Maybe it's one of those cases where we need a CUDA format. As to local vs. private, I think we should also try using both at once, especially on Kepler where they are similar speed. Perhaps have separate functions in the kernel, one with local and the other with private, and direct even vs. odd candidates to them. We previously considered this for local vs. global, but the optimal GWS for these would be too different, so we'd need to run separate kernels. We may in fact want to introduce a bcrypt-global-opencl, to be used simultaneously with our main bcrypt-opencl (invoking two instances of john manually, on different candidate password streams?) for a greater cumulative speed. Alexander
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