Tim Chevalier wrote:
2008/9/8 Vlad Skvortsov <[EMAIL PROTECTED]>:
Posting to cafe since I got just one reply on [EMAIL PROTECTED] I was suggested
to
include more SCC annotations, but that didn't help. The 'serialize' function
is still reported to consume about 32% of running time, 29% inherited.
However, functions called from it only account for about 3% of time.
If "serialize" calls standard library functions, this is probably
because the profiling libraries weren't built with -auto-all -- so the
profiling report won't tell you how much time standard library
functions consume.
Hmm, that's a good point! I didn't think about it. Though how do I make
GHC link in profiling versions of standard libraries? My own libraries
are built with profiling support and I run Setup.hs with
--enable-library-profiling and --enable-executable-profiling options.
You can rebuild the libraries with -auto-all, but probably much easier
would be to add SCC annotations to each call site. For example, you
could annotate your locally defined dumpWith function like so:
dumpWith f = {-# SCC "foldWithKey" #-} Data.Map.foldWithKey f []
docToStr k (Doc { docName=n, docVectorLength=vl}) =
(:) ("d " ++ show k ++ " " ++ n ++ " " ++ (show vl))
Here is how my current version of the function looks like:
serialize :: Database -> [[String]]
serialize db =
{-# SCC "XXXCons" #-}
[
[dbFormatTag],
({-# SCC "dwDoc" #-} dumpWith docToStr dmap),
({-# SCC "dwTerm" #-} dumpWith termToStr tmap)
]
where
(dmap, tmap) = {-# SCC "XXX" #-} db
dumpWith f = {-# SCC "dumpWith" #-} Data.Map.foldWithKey f []
docToStr :: DocId -> Doc -> [String] -> [String]
docToStr k (Doc { docName=n, docVectorLength=vl}) =
{-# SCC "docToStr" #-} ((:) ("d " ++ show k ++ " " ++ n ++ " " ++
(show vl)))
termToStr t il =
{-# SCC "termToStr" #-} ((:) ("t " ++ t ++ " " ++ (foldl
ilItemToStr "" il)))
ilItemToStr acc (docid, weight) =
{-# SCC "ilItemToStr" #-} (show docid ++ ":" ++ show weight ++ "
" ++ acc)
...and still I don't see these cost centers to take a lot of time (they
add up to about 3%, as I said before).
Then your profiling report will tell you how much time/memory that
particular call to foldWithKey uses.
By the way, using foldl rather than foldl' or foldr is almost always a
performance bug
Data.Map.foldWith key is implemented with foldr[1], however I'm not sure
I'm getting how foldr is superior to foldl here (foldl' I understand).
Could you shed some light on that for me please?
Thanks!
[1]:
http://www.haskell.org/ghc/docs/latest/html/libraries/containers/src/Data-Map.html
--
Vlad Skvortsov, [EMAIL PROTECTED], http://vss.73rus.com
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