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Date: Tue, 2 Jul 2013 20:52:57 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: bug: GPU use in CPU-only formats

On Tue, Jul 02, 2013 at 05:44:16PM +0200, magnum wrote:
> I'm not so sure they really do. Might be a driver quirk. I can reproduce it like this:
> 
> screen 1$ nvidia-smi
> (get baseline)
> 
> screen 0$ ../run/john -t=10 -form:raw-sha256-ng
> screen 1$ nvidia-smi
> (64 MB memory is allocated, temp/fans increase a little)

Yeah.  And the temp/fan speed will increase further if you keep this
running for longer, stabilizing at about 62C and 50%.  I think this is
roughly half-load.  At full load, the card gets to e.g. 82C and 80%.

Run several CPU-only john processes from an -opencl build
simultaneously, and the memory usage on the NVIDIA card will increase
further (approx. 60 MB per john process).

> The temp increase (a few degrees) may actually be due to CPU heat, right?

It could have been, but I am convinced that it mostly is not.  The
NVIDIA card itself does emit hot air under such conditions.

> What would be the equivalence of nvidia-smi for AMD?

user@...l:~$ DISPLAY=:0 aticonfig --odgt

Default Adapter - AMD Radeon HD 7900 Series 
                  Sensor 0: Temperature - 47.00 C
user@...l:~$ DISPLAY=:0 aticonfig --pplib-cmd 'get fanspeed 0'
Fan speed query: 
Query Index: 0, Speed in percent
Result: Fan Speed: 20%

user@...l:~$ DISPLAY=:0 aticonfig --odgc

Default Adapter - AMD Radeon HD 7900 Series 
                            Core (MHz)    Memory (MHz)
           Current Clocks :    300           150
             Current Peak :    925           1375
  Configurable Peak Range : [300-1125]     [150-1575]
                 GPU load :    0%

I don't know how to retrieve the memory usage, though.

Alexander

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