Re: [Gretl-devel] sorting string arrays
Am 11.04.2019 um 22:20 schrieb Allin Cottrell:
On Thu, 11 Apr 2019, Artur Tarassow wrote:
> Am 11.04.19 um 18:12 schrieb Sven Schreiber:
>> Am 11.04.2019 um 17:55 schrieb Artur Tarassow:
>>> Just out of curiosity: Gretl wouldn't compute stuff in parallel
>>> out-of-box, right?
>>
>> Hehe, well if "somebody" implemented the cross-array operation
natively
>> and used OpenMP or stuff like that then perhaps it would... otherwise:
>> not, I guess.
>
> Of course, I rather meant (without saying it explicitly) whether there
> is some way to exploit C in a simple way to do this. But I guess this
> is rather a non-trivial issue...
Yes, non-trivial. The thing is, with feval() "anything could happen"
(that is, any part of the libgretl code could be visited as a result of
the function call). Getting this right with OpenMP would require that
libgretl as a whole is thread-safe.
Hm, not sure I understand this point in the given context. What I
thought Artur meant is that for a given array of matrices the same
operation should be applied to every array member. That sounds to me
like a natural parallelization task without race conditions and so on.
OK, I guess one has to rule out that the operation itself accesses
sister elements in the same array, and I admit that ensuring this may
not be trivial.
But say you want to apply cdemean() to every matrix in an N-element
matrices array. In principle it wouldn't be too difficult to distribute
that task to different threads/cores, no?
Of course for small arrays the overhead may kill the performance gain.
thanks
sven