On Thu, Nov 8, 2012 at 3:48 PM, Cedric Greevey <cgree...@gmail.com> wrote:
> I have the following code to perform a complicated image convolution. It > takes 10-15 seconds with output dimensions 256x256 and samples 6. No > reflection warnings, and using unchecked math doesn't speed it up any. I've > tried to ensure it uses primitive math inside the loops, aside from > generating the outer loop's values. What cached-load-chunk does shouldn't > matter much, but in most cases it should boil down to a map lookup inside a > swap! and a couple of atom derefs and function calls. The bottleneck is > likely in the math somewhere, and likely something is being boxed, though > I've primitive-coerced every numerical let and loop value and avoided more > than two arguments per arithmetic op. > > Can anyone spot anything I haven't that could be causing boxed arithmetic > inside the loops? > I've now checked for Var lookups (none outside the caching function, and now none inside either) and checked the caching code itself (there's a .get on a closed-over ConcurrentHashMap, a null check, a .get on a SoftReference, and another null check, on each lookup, if there isn't a cache miss on that lookup; plus a couple more method calls for the IFn invokes and an ivar fetch to get the ConcurrentHashMap reference). In the absence of cache misses I'm still seeing ~3.5 *minutes* at 1280x720 with 10 samples (= about 100 million iterations total of the inner loop). The arithmetic in there is 23 floating-point ops, five compares, a log, an atan, and three bitwise ANDs. Without the log and atan a hundred million of that inner loop should take a second on this box. I very much doubt the log and the atan are 209 times slower than the rest of it combined. So there's three likely culprits: boxing, two calls to (rand), and the BufferedImage .getRGB method call (on a 6000x2198 24bpp image, though its size should matter not), unless trig is really that slow. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
