[A51] Query - Use of Kraken with CPUs

Joel Eriksson joel.eriksson at gmail.com
Wed Mar 26 18:02:12 CET 2014


PS. Kraken will use all available CPU cores (of course), when using the CPU
based code. Using it, with a high end multi-core machine, does not even
come close to using a GPU.


On Wed, Mar 26, 2014 at 5:58 PM, Joel Eriksson <joel.eriksson at gmail.com>wrote:

> Radeon GPUs were originally made by ATI. ATI was later acquired by AMD,
> but the GPUs are certainly not AMD CPUs and the performance when it comes
> to the kind of computations that are required for A5/1 and crypto in
> general is not even close when you compare CPUs and GPUs. The reason for
> this is mainly because in a single GPU, there are actually up to thousands
> of cores that performs the actual computations. In the case of Radeon HD
> 6990, for instance, you have 2 GPUs that have 1536 cores each, so 3072
> cores in total. Compare that to an ordinary CPU, and you realize that a
> multi core CPU does not even come close. :)
>
> So no, it's not about using the GPU to get some extra power instead of
> just letting it sit idle. GPUs are way, way faster than CPUs for this kind
> of stuff. For a bit more detailed information about why this is the case, I
> advise you to read this:
>
> https://en.bitcoin.it/wiki/Why_a_GPU_mines_faster_than_a_CPU
>
> Quote:
> "A CPU core can execute *4* 32-bit instructions per clock (using a
> 128-bit SSE instruction) or *8* via AVX (256-Bit), whereas a GPU like the
> Radeon HD 5970 can execute *3200* 32-bit instructions per clock (using
> its 3200 ALUs or shaders). This is a difference of *800 (or 400 in case
> of AVX) times more instructions per clock*."
>
> Specifically, AMD/ATI GPUs are the best suited for these kinds of
> computations, which is why they are used rather than NVidia based cards.
> This is because AMD/ATI cards (once again, GPUs, not CPUs ;) have a number
> of features that make them well suitable for high performing integer
> operations. Traditionally, GPUs are better suited for floating point
> operations because that is more important for gaming/graphics performance
> in general. If we take Bitcoin mining (i.e SHA-256 computations) as an
> example, the Radeon HD 7970 is about five times as fast as the GTX 680.
>
> Regards,
> Joel Eriksson
> clevcode.org
>
>
>
>
>
> On Wed, Mar 26, 2014 at 5:39 PM, Nikos Balkanas <nbalkanas at gmail.com>wrote:
>
>>
>>
>>
>> On Wed, Mar 26, 2014 at 5:12 PM, Joel Eriksson <joel.eriksson at gmail.com>wrote:
>>
>>> Using CPUs instead of GPUs doesn't make any sense at all, CPUs are a
>>> _lot_ slower than GPUs for these kinds of computations and you would need a
>>> cluster (i.e much more expensive) to be able to get similar performance.
>>>
>>>
>> You don't need a cluster for a multiprocessing board. Just a
>> multiprocessing kernel that linux provides. Radeon's GPUs are, to my
>> knowledge, AMD CPUs, but at lower frequencies. Granted, you don't have a
>> general kernel running on top of them, but an MP kernel has load balancing
>> and preemptive multitasking that kraken hasn't. ;-)
>>
>> But we are in agreement here. If you have a GPU sitting idle, why not
>> take advantage of it?
>>
>> To really crush both CPUs and GPUs, you could create an ASIC for it
>>> instead. I bet that there are A5/1 cracking ASICs out there already, just
>>> not in the hands of the public AFAIK. Using FPGAs would be a decent middle
>>> ground.
>>>
>>
>> Yeap.
>>
>>>
>>> Cheers,
>>> Joel
>>>
>>>
>>> On Wed, Mar 26, 2014 at 2:22 PM, Nikos Balkanas <nbalkanas at gmail.com>wrote:
>>>
>>>>
>>>>
>>>>
>>>> On Wed, Mar 26, 2014 at 1:51 PM, Joel Eriksson <joel.eriksson at gmail.com
>>>> > wrote:
>>>>
>>>>> It will be _a lot_ slower. If you want to have any chance of
>>>>> intercepting frequency hopping calls (without having receivers constantly
>>>>> recording everything at each of the possible frequencies) you need to use
>>>>> GPUs and SSDs. If you don't have to deal with frequency hopping, and don't
>>>>> have to decipher in near real-time, it doesn't matter as much.
>>>>>
>>>>> Regards,
>>>>> Joel
>>>>>
>>>>>
>>>> In such case, wouldn't it make more sense to have more CPUs on the MB?
>>>>
>>>>
>>>>> On Wed, Mar 26, 2014 at 11:36 AM, Nikos Balkanas <nbalkanas at gmail.com>wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wed, Mar 26, 2014 at 8:40 AM, Amber and Sarosh <
>>>>>> amber_sarosh at hotmail.com> wrote:
>>>>>>
>>>>>>> Hi All,
>>>>>>> Can anyone please guide if GPUs are necessary for rainbow table
>>>>>>> lookup using kraken to find the key to decipher an intercepted
>>>>>>> communication or is it possible to do this using just CPUs? In case the
>>>>>>> later is possible how much time it will take approximately?
>>>>>>>
>>>>>>>
>>>>>> GPUs are not necessary, just desirable. If GPUs are missing, kraken
>>>>>> will still work with A5Cpu.so, but it will be somewhat slower. Assuming
>>>>>> that during cracking your PC is CPU limited, the benefit should scale
>>>>>> roughly with your setup ratio of GPU power/CPU power. In reality you will
>>>>>> run into RAM and table I/O bottlenecks before that. In short it is highly
>>>>>> depended on your setup ;-)
>>>>>>
>>>>>> The idea is, that the easier factor to improve is the CPU, so why not
>>>>>> do it?
>>>>>>
>>>>>> Nikos
>>>>>>
>>>>>>> Regards,
>>>>>>> Naheed, Amber & Sarosh
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> A51 mailing list
>>>>>>> A51 at lists.srlabs.de
>>>>>>> https://lists.srlabs.de/cgi-bin/mailman/listinfo/a51
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> A51 mailing list
>>>>>> A51 at lists.srlabs.de
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>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Best Regards,
>>>>>   Joel Eriksson
>>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Best Regards,
>>>   Joel Eriksson
>>>
>>
>>
>
>
> --
> Best Regards,
>   Joel Eriksson
>



-- 
Best Regards,
  Joel Eriksson
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