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Date: Sat, 6 Jun 2015 15:00:42 +0200
From: Agnieszka Bielec <bielecagnieszka8@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: PHC: Lyra2 on CPU
2015-06-06 14:44 GMT+02:00 Solar Designer <solar@...nwall.com>:
> On Sat, Jun 06, 2015 at 02:33:55PM +0200, Agnieszka Bielec wrote:
>> #include <stdio.h>
>> #include <omp.h>
>>
>> static void func()
>> {
>> char t[30];
>> sprintf(t,"%d %d\n",omp_get_num_threads(),omp_get_thread_num());
>> write(0,t,10);
>> write(0,"checkpoint 1\n",13);
>> #pragma omp barrier
>> write(0,"checkpoint 2\n",13);
>> #pragma omp barrier
>> write(0,"checkpoint 3\n",13);
>> #pragma omp barrier
>> write(0,"checkpoint 4\n",13);
>> }
>
> stdout is fd 1, not 0. It's curious this produced output at all.
>
> Also, you're printing some garbage from the stack in the first write().
> It should be:
>
> write(1,t,strlen(t));
>
> Other than that, your program works for me (doesn't block).
>
>> output:
>> none@...e ~/Desktop $ ./omp
>> 8 0
>> checkpoint 1
>> 8 1
>> checkpoint 1
>> checkpoint 2
>> checkpoint 2
>> [blocks]
>
> This is as expected, except for it blocking, right? Will it still block
> for you if you correct the errors above?
yes, yes, it blocks on my laptop and on super.
>
> BTW, note that:
>
> #pragma omp parallel for
> for(i=0;i<2;i++)
>
> isn't guaranteed to actually spawn two threads for the two iterations.
> It probably will (as long as OMP_NUM_THREADS is at least 2, or is not
> set and the system has at least two logical CPUs), but it is also
> allowed to just execute the two iterations sequentially. Observe:
but it looks like omp creates 8 threads. I have 8 in the place where
you have 2. I will ask on omp forum about this but i need to wait
until admin accept my registration
>
> $ ./b
> 2 1
> checkpoint 1
> 2 0
> checkpoint 1
> checkpoint 2
> checkpoint 2
> checkpoint 3
> checkpoint 3
> checkpoint 4
> checkpoint 4
> $ OMP_NUM_THREADS=1 ./b
> 1 0
> checkpoint 1
> checkpoint 2
> checkpoint 3
> checkpoint 4
> 1 0
> checkpoint 1
> checkpoint 2
> checkpoint 3
> checkpoint 4
thanks, I needed output from someone's else computer
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