[CoLoCo] How do I make a program fully utilize my dual-core processor?

Neal McBurnett neal at bcn.boulder.co.us
Tue Oct 6 03:14:59 BST 2009


http://pdfcrack.sourceforge.net/faq.html says it can be done:

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Does PDFCrack support distributed and/or multicore/multicpu-systems?

Not yet. The project is open for contributions! ;)
Distributed workloads can be done by some clever working with the
save-files though but I have not tried it.
----

I don't know what it means about save-files, but I suggest looking into it.

Neal McBurnett                 http://neal.mcburnett.org/

On Mon, Oct 05, 2009 at 08:30:35PM -0400, Ringo wrote:
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> I'm actually using pdfcrack, so I'm not technically breaking a hash.
> Unfortunately, it only seems to do one thread at a time. I suppose I
> could have one instance working on an x character password and one
> instance working on an x+1 character password but that would require
> some monitoring.
> 
> It's the only pdf cracking utlility I've found but if people know of
> others I'd be thrilled to try them.
> 
> Ringo
> 
> Ryan Maki wrote:
> > Additionally, serious password cracking software might also be able to
> > utilize your graphics card, depending on make and model.~Ryan
> > 
> > On Mon, Oct 5, 2009 at 4:30 PM, Neal McBurnett <neal at bcn.boulder.co.us>wrote:
> > 
> >> I'd be surprised if good cracking applications didn't already have an
> >> option to do multi-threading to use all your cores.  What software are
> >> you using?
> >>
> >> -Neal
> >>
> >> On Sat, Oct 03, 2009 at 06:51:37PM -0400, Ringo wrote:
> > Thanks for all of the great responses! Looks like for now I'll be
> > sticking to just one core for cracking. Recovering this password
> > unfortunately isn't enough of a justification for me to go in and hack
> > the source.
> > 
> > Ringo
> > 
> > NICK VERBECK wrote:
> >>>>> If you wrote the program yourself or have access to the source. You
> >>>>> could extend it to use Threads. However with threads you can truly
> >>>>> only fire-up as many threads as you have cores. Each thread will use a
> >>>>> separate core to run in, but once you get 2 threads in the same core
> >>>>> you will start context switching between each thread in that core
> >>>>> slowing down the actual speed of those 2 threads.
> >>>>>
> >>>>> On Sat, Oct 3, 2009 at 8:31 AM, Neal McBurnett <neal at bcn.boulder.co.us>
> >>> wrote:
> >>>>>> In general, the problem you identify is one of the most daunting
> >>>>>> issues facing computer science.  It is getting much harder to speed up
> >>>>>> individual processors, so the way to give people more power is to give
> >>>>>> them more cores.  But we often can't find a suitable way to take
> >>>>>> advantage of them to solve a given problem....
> >>>>>>
> >>>>>>  http://en.wikipedia.org/wiki/Parallel_computing
> >>>>>>
> >>>>>> It all depends on exactly what you want to do.  You are in luck
> >>>>>> because recovering a password is easily done in parallel, as James
> >>>>>> notes.  But many other interesting tasks can't be easily parallelized.
> >>>>>>
> >>>>>> Neal McBurnett                 http://neal.mcburnett.org/
> >>>>>>
> >>>>>> On Sat, Oct 03, 2009 at 07:35:00AM -0600, James Wyatt wrote:
> >>>>>>> Assuming both instances can work on different hashes you could run
> >>> your
> >>>>>>> app twice and assign processor affinity to each process.
> >>>>>>>
> >>>>>>> http://www.linuxjournal.com/article/6799
> >>>>>>>
> >>>>>>>
> >>>>>>> You could do something with erlang if you wanted to do it with style,
> >>>>>>> but that would certainly be overkill.
> >>>>>>>
> >>>>>>> Jim
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> On Sat, Oct 3, 2009 at 1:31 AM, Ringo <2600denver at gmail.com> wrote:
> >>>>>>>
> >>>>> Hey Ubuntu experts,
> >>>>>
> >>>>> I've got an intel dual-core processor which Ubuntu (intrepid) runs
> >>> great
> >>>>> on. It will fully utilize both cores if I've got lots of programs
> >>>>> running but each program is confined to only one core.
> >>>>>
> >>>>> I've looked around online to find out how to make a program use both
> >>>>> cores, but I can't find any advice on this outside of the convoluted
> >>>>> process of running a program inside a virtual machine. I'm trying to
> >>>>> recover a password from a hash and one core is at 100% while the other
> >>>>> is around 3% usage.
> >>>>>
> >>>>> Any ideas?
> >>>>>
> >>>>> Thanks,
> >>>>> Ringo
> >>>>>
> >>>
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