Hello Denis, Wednesday, January 7, 2009, 6:56:36 PM, you wrote:
memory allocated for i :))) each new copy of i needs one word. the situation was much worse with Int64, of course :) > Hi all, > I'm seeing a lot of unexpected memory allocation with some simple code that > copies the contents of one vector (IOUArray Int Int64) into another of the > same type and dimensions. In particular, profiling reveals that `copyInto' > is allocating oodles and oodles of memory. > My small test case creates two 50000-element arrays and performs 10000 > copies from one into the other. Since the elements are Int64s and the > arrays are unboxed, each array should be > 50000 elements * 8 bytes per element = 400,000 bytes > and so the arrays should only take 800,000 bytes total. I understand > there's some overhead for thunks and whatnot, but the profiler reported > allocation is around 40 billion bytes. And almost all of that allocation is > in my copying function, not in main (main allocates the arrays). > I've attached two versions of the code, just for comparison. The only > difference is the way the copying is done. One calls `getBounds' to figure > out the bounds, and one is given the bounds for copying. They're both about > the same speed and allocation (originally I was using IOUArray Int64 Int64, > and there was a much greater allocation difference between the two versions; > but that went away. Oh well). > So, does anyone know why copying takes so much allocation? I expect there > is _some_ way to just move memory from one array to another, like a memcpy > -- how can I do that? > Denis -- Best regards, Bulat mailto:bulat.zigans...@gmail.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
