On Mon, Oct 27, 2008 at 12:34 AM, Alexander Dunlap <[EMAIL PROTECTED]> wrote: > On Sun, Oct 26, 2008 at 9:36 AM, John Lato <[EMAIL PROTECTED]> wrote: >> Hello, >> >> I was experimenting with using ghc-6.10.0.20081007 on a project, and >> it seems that binary-0.4.3.1 has markedly worse performance in certain >> cases. With the following simple test: >> >>> import qualified Data.ByteString.Lazy as L >>> import Data.Binary >>> import Data.Binary.Get >>> import Control.Monad >>> >>> main :: IO () >>> main = do >>> b <- L.readFile "some_binary_file" >>> putStrLn $ show $ runGet getter b >> >>> getter :: Get [Word16] >>> getter = replicateM 1000000 getWord16le >> >> running this program compiled with ghc-6.10 takes about 4 times as >> long (and consumes much more memory) as when compiled with ghc-6.8.3. >> The extra time appears to be proportional to the number of elements >> processed in the Get. Running the programs with -hT shows a clear >> memory difference, which I think is the source of the problem. I've >> placed pdfs of that output at https://webspace.utexas.edu/latojw/data/ >> >> The difference seems to manifest itself only when the elements are >> actually processed; changing "show $ runGet " to "show $ length $ >> runGet " is slightly faster in 6.10. >> >> I was working on an Intel Mac with OS 10.4, binary-0.4.3.1, and >> bytestring-0.9.1.4. Can anyone confirm this, or suggest what might be >> the difference? >> >> Thank you, >> John Lato >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> > > With GHC 6.8.2: > > test: too few bytes. Failed reading at byte position 1613914 > > real 0m27.573s > user 0m12.917s > sys 0m0.087s > > With GHC 6.11.20081003: > > test: too few bytes. Failed reading at byte position 1613914 > > real 0m21.528s > user 0m14.759s > sys 0m0.135s > > I'm not using the exact same versions as you are, but I seem to be > getting different results. >
Hi Alexander, Thanks for trying this out. Based on your error, I'd guess that the file isn't large enough to read all the requested data. In my case, it was about 70MB. You could try reading from /dev/random, or rather than reading from a file, use something like >> test_pure = let b = Data.ByteString.Lazy.repeat 1 in putStrLn $ show $ >> runGet getter b I haven't tried a pure version myself, so I don't know what to expect from it. Something to do tonight... Cheers, John _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
