[Haskell-cafe] performance difference for binary-0.4.3.1 with
ghc-6.8.3 and ghc-6.10
halomoan.donald at gmail.com
Tue Oct 28 23:40:48 EDT 2008
Where can I get ghc-6.10? I cannot see it at haskell.org website.
On 2008-10-29, Don Stewart <dons at galois.com> wrote:
>> I was experimenting with using ghc-188.8.131.5281007 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?
> Is this the sole test case?
> I can investigate. Though perhaps using a newer GHC release candidate is
> also a good idea.
> -- Don
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