Sure. And I'm seeing a good speed-up on my 2-core machine indeed: Without parallel loop:
real 0m0.923s user 0m0.875s sys 0m0.045s With parallel loop: real 0m0.544s user 0m0.876s sys 0m0.045s Which is pretty awesome, given the simplicity of Cython parallel implementation :) Thanks a lot Mark! 2011/8/3, mark florisson <markflorisso...@gmail.com>: > On 3 August 2011 14:18, Francesc Alted <fal...@pytables.org> wrote: >> Hi, >> >> I'm trying to take advantage of the exciting new parallelizing >> capabilities recently introduced in forthcoming 0.15 version, but I'm >> having a small difficulty. When I try to compile a small demo routing >> (attached), I'm getting this error: >> >> $ cython -a mandel.pyx >> >> Error compiling Cython file: >> ------------------------------------------------------------ >> ... >> for pix in prange(num_pixels, nogil=True, schedule="dynamic"): >> x = pix % width >> y = pix // width >> cr = begin_r + (x * span_r / (width + 1.0)) >> ci = begin_i + (y * span_i / (height + 1.0)) >> n = MandelbrotCalculate(cr, ci, maxiter) >> ^ >> ------------------------------------------------------------ >> >> mandel.pyx:50:31: Calling gil-requiring function not allowed without gil >> >> While trying to figure out why MandelbrotCalculate does require GIL, I >> replaced the "for prange", by a trivial "for range", and the >> annotated HTML source reveals that the only line in (light) yellow in >> this function is >> >> return n >> >> which is translated as: >> >> /* "mandel.pyx":22 >> * ti = 2*zr*zi + ci >> * zr, zi = tr, ti >> * return n # <<<<<<<<<<<<<< >> * >> * @cython.boundscheck(False) >> */ >> __pyx_r = __pyx_v_n; >> goto __pyx_L0; >> >> __pyx_r = 0; >> __pyx_L0:; >> __Pyx_RefNannyFinishContext(); >> return __pyx_r; >> } >> >> My guess is that this __Pyx_RefNannyFinishContext() call is preventing >> to call the routing from the parallel loop. Is that a bug, a >> limitation of current implementation or it is just that I'm missing >> something? >> >> Thanks, >> >> -- >> Francesc Alted >> >> _______________________________________________ >> cython-devel mailing list >> cython-devel@python.org >> http://mail.python.org/mailman/listinfo/cython-devel >> >> > > Hey Francesc! > > The problem is that you didn't declare MandelbrotCalculate 'nogil'. > You have to write > > cdef long MandelbrotCalculate(double cr, double ci, long maxiter) nogil: > ... > > That's all, and it will compile :) > > Cheers, > > Mark > _______________________________________________ > cython-devel mailing list > cython-devel@python.org > http://mail.python.org/mailman/listinfo/cython-devel > -- Francesc Alted _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
