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Date: Wed, 4 Dec 2013 10:48:08 +1100
From: Michael Samuel <mik@...net.net>
To: john-users@...ts.openwall.com
Subject: Re: Energy-efficient bcrypt cracking (Passwords^13 slides)
On 4 December 2013 09:26, Solar Designer <solar@...nwall.com> wrote:
> It was tricky. For these measurements, we used GPUs in two machines:
> bull (HD 7970 and GTX 570) and super (HD 7990 and GTX TITAN). For bull,
> I was measuring its total power consumption from the 220V AC socket, so
> we had to rely on the idle-to-load deltas and on the vendors' published
> power consumption figures for these GPUs at idle. For super, I obtained
> deltas for both AC and 12V DC via IPMI, which in turn got them from
> super's two PSUs via PMBus. bull's PSU is officially 85% efficient.
> super's PSUs officially have over 94% efficiency, and there was in fact
> not much difference between AC and 12V DC deltas for GPU load.
I think the power-socket measurements are possibly interesting too - although
I understand they'd be expensive/annoying to get a fair measurement of, as
you'd need to optimise the system for the purpose of energy-efficient
cracking. This might be possible by turning off unused cores and PCI-E
devices via sysfs on Linux systems.
The slides looked great, and the comparisons were obviously still very useful
as comparisons.
Great work Katja on the Epiphany and FPGA work - those threads on john-dev
were very enlightening.
Regards,
Michael
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