Hi, I would argue you have some serious problem with your setup if copying of 1MB takes time in the order of minutes (and even if its milliseconds, i would consider this as way too much). I am also concerned that your new cpu timing is 0.
that resizing takes longer on a gpu is expected as you are doing something way more complicated when allocating storage on the gpu, compared to a cpu. Also consider doing some real work. computing the norm of a 1MB vector is not really something one would consider the gpu for. All simple vector operations/reductions are a pain to get fast on a gpu. compare matrix-matrix multiplications or similar. On 2017-02-18 16:02, Sensei wrote: >> The GPU is an Intel HD Graphics 4000. >> >> What worries me is not only the warmup, but the copy phase. In >> release it can take a lot of time for a simple 1M items (169 >> seconds!). I suspect I should try to do everything on the GPU. Not >> only that, but this call: >> >> viennacl::vector<float> gpuv; >> gpuv.resize(size); >> >> is taking 6 times what it takes on the CPU. >> >> How can I avoid these overheads? I am quite new with OpenCL... >> >> Thank you! > > Sorry, I forgot the log for the twice-computed norm: > > COMPUTING NORM_1 ON GPU > COMPUTING NORM_1 ON GPU 347 > > COMPUTING NORM_1 ON GPU (AGAIN) > COMPUTING NORM_1 ON GPU 2 > > COMPUTING NORM_1 ON CPU > COMPUTING NORM_1 ON CPU 0 > > As you can see, yes, the OpenCL compilation takes a lot of time, but > still higher than the CPU (with cache and all, I know). > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > ViennaCL-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/viennacl-devel ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ ViennaCL-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/viennacl-devel
