Hi Niko, to, 2006-11-23 kello 12:11 +0200, Niko Korhonen kirjoitti:
I've tried applying seq and some other strictness tricks (such as x == x) pretty much everywhere on the code with no results. Could you please help me understand what is going on here? Have I misunderstood something critical in how Haskell works? Here is the relevant portion of the code:
main = do -- This should allocate a 40 MB array buf <- newArray_ (0, 10000000) :: IO Buffer -- Fill the array with dither genSeries buf tpdf (2, 12)
main = do -- This should allocate a 40 MB array buf <- newArray_ (0, 100000000) :: IO Buffer -- Fill the array with dither genSeries buf tpdf (2, 12) a <- readArray buf 100000000 putStrLn $ "a is " ++ (show a) By adding -O3 -optc-O3 -funfolding-use-threshold=16 compile flags the above code with 100'000'000 elements worked. And by still adding -ddump-simpl > core.txt flag and looking the generated core, the worker-loop seemed to use primitives. I cannot say, if this was the helping part here. Have you tried profiling: -prof -auto-all and running with +RTS -p -RTS? Or running with +RTS -sstderr gives 14,257,786,344 bytes allocated in the heap 4,282,040 bytes copied during GC (scavenged) 1,646,936 bytes copied during GC (not scavenged) 80,733,232 bytes maximum residency (2 sample(s)) 27045 collections in generation 0 ( 0.31s) 2 collections in generation 1 ( 0.00s) 78 Mb total memory in use INIT time 0.00s ( 0.00s elapsed) MUT time 22.61s ( 24.07s elapsed) GC time 0.31s ( 0.32s elapsed) EXIT time 0.00s ( 0.00s elapsed) Total time 22.92s ( 24.39s elapsed) %GC time 1.3% (1.3% elapsed) Alloc rate 630,612,876 bytes per MUT second Productivity 98.6% of total user, 92.7% of total elapsed It seems that garbage collector has not used very much time here. There is more information on haskell wiki: http://www.haskell.org/haskellwiki/Performance http://www.haskell.org/haskellwiki/Performance/GHC This GHC specific part does not mention -O3 -optc-O3 -funfolding-use-threshold=nn flags. They were hinted here on this list; I have found them very helpful a couple of weeks ago - thanks again :) btw, Could the GHC specific wiki page be updated to contain and explain these flags? Hopefully this helped you a bit! And hopefully someone who knows how these things go have time to give you a detailed answer! br, Isto