Hi Andreas On Fri, Aug 12, 2011 at 11:28 AM, Andreas Neumann <[email protected]> wrote: > Hi, > > Now that Martin is including Multithreading Support, I am also wondering if > it would be feasible to also profit from the computing power of GPUs and > libraries, such as OPENCL. Seems like mobile devices, servers and regular > desktops would benefit. Would the Qgis architecture allow the usage of > OpenCL? > > I am not a dev, but am reading about these new technical options ...
Given that more and more computers come with powerful GPUs it really makes sense to explore what are the possibilities for speed improvements. In general you can either use a library that implements some algorithms on GPU or you can start writing your own GPU code for the algorithm (or some parts of it). The speedup will vary greatly depending on the algorithm. Things like 3D rendering, image processing, video compression etc. are perfectly suited for GPU implementation because one computationally intensive routine is used in parallel for millions of independent pixels. However many other algorithms will not perform better on GPU. These are typically the ones that are not parallel or their bottleneck is not in computation - many algorithms have bottlenecks in I/O or they need to wait for some resources. First we would have to identify what is slow and should be optimized. Then do some profiling to find out in what parts most of the time is spent. If those parts are computationally intensive and parallelizable then it is a candidate for GPU implementation. My impression is that there are very few places in QGIS where we would gain performance with GPU because typically we delegate computation to underlying libraries and/or the slowness is caused by I/O. And various pieces of functionality are slow just because inefficient or naive algorithms are used. When implementing an algorithm on GPU we still would need to provide original implementation if no OpenCL-capable device is found. So this adds additional burden on maintainance to ensure that both CPU and GPU implementations give equivalent results. To summarize: yes, it would be possible to use GPU for some tasks, but GPU is not a magic wand. Computationally intensive tasks really can be improved (even by factors of 100), but many other tasks would not get faster. What are the areas where you think QGIS should be faster? Martin _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
