On 3 August 2011 14:33, Francesc Alted <fal...@pytables.org> wrote: > 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! >
Glad you like it, nice speedup! > 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 > _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
