10-07-2013, 09:18 AM
(10-07-2013, 08:26 AM)epixoip Wrote: you haven't really given us a whole lot of well-presented data
Maybe its not well presented but I think all the data you need is there. Could you specify what more data I could provide. I direct your attention to these two cases in particular:
hashcat-cli64.exe -m5500 -a0 -c 1000 -n3 --remove --pw-min=8 -o out in200 ..\Dic\04 -r append4.rule
Speed/sec.: 92.16M plains, - words
cudaHashcat-plus64.exe -m5500 -a3 --gpu-temp-disable --remove -o out in200 ?u?l?l?l?d?d?d?s
Speed.GPU.#1...: 2365.0 kH/s
(10-07-2013, 08:26 AM)epixoip Wrote: ...but you need to remember that you actually have to give gpus work to do. if you give them a small amount of work, you will not achieve full acceleration. 100MB of words is not a lot of work for fast algorithms
again.. the GPU (oclhashcat) is using a mask (?u?l?l?l?d?d?d?s) i.e. brute force NOT the 100mb word list. Is that not enough work for a GTS250?
In both case the keyspace is alpha for the first four chars and ?d?d?d?s for the char 5 to char 8. In the hashcat case this is done with the append4.rule and the 04 dictionary.
(10-07-2013, 08:26 AM)epixoip Wrote: i can't say it enough: gpus aren't magic.
epixoip didn't you just say:
(10-07-2013, 08:26 AM)epixoip Wrote: come on, everyone knows that gpus are faster than cpus! gpus are magic.
lol...sorry I just had to put that in there
(10-07-2013, 08:26 AM)epixoip Wrote: you have to optimize your attacks in order to use gpus efficiently. and in some cases, gpus are simply the wrong choice.
Yup I understand that. I am not going to crack passwords with oclhashcat 2365.0 kH/s when I can do it at 92.16M with hashcat. GPU definitely wrong choice here (thought its a bit surprising).
But my reason for starting this post was why this was the case. Because up till now I hadn't seen an example of the GPU being slower (considering I saturate it with enough words) then the CPU. And certainly not 40x slower.
Also naive as I maybe
you haven't given me the reason why this very specific case might slower on the GPU. I think you will agree with me this is not a case of not giving the GPU enough to work.If required I could share test cases with you for you to check and see for your self. Thanks.