From: Simon Marlow [mailto:simonmar@microsoft.com]

PackedStrings are still slow in 6.x. I know there are various other PackedString implementations out there, we just need to incorporate one.

They certainly seem to be. Below are the profiles (compiled with -O2; ran them twice; took the second run) of Simon's old PackedString version, and Alson's Hash version. Simon's uses way more memory, too. I might try some more profiling later to narrow down the slow bits.

From: Alson Kemp [mailto:Alson.Kemp@sloan.mit.edu]

I tried Simon's version, but it throws a "Fail: Ix{Int}.index: Index (5) out of range ((0,4))" error. Haven't tracked down the cause yet.

Here's the fix (subtract one from (lengthPS ps)): -- Looks bad, but GHC does a great job of optimising it: hashPS :: PackedString -> Int hashPS ps = foldr f 0 (map (ord.indexPS ps) [0..((lengthPS ps) - 1)]) where f n m = n + m * 128 `mod` 1048583 ------------------------------- Alson's: spellcheck +RTS -p -hr -H10m -K20m -RTS total time = 1.84 secs (92 ticks @ 20 ms) total alloc = 69,112,588 bytes (excludes profiling overheads) COST CENTRE MODULE %time %alloc main Main 58.7 21.2 spellcheck Main 23.9 34.2 buildHash Main 17.4 44.6 individual inherited COST CENTRE MODULE no. entries %time %alloc %time %alloc MAIN MAIN 1 0 0.0 0.0 100.0 100.0 main Main 146 1 58.7 21.2 100.0 100.0 spellcheck Main 149 0 23.9 34.2 23.9 34.2 buildHash Main 148 1 17.4 44.6 17.4 44.6 CAF Main 140 1 0.0 0.0 0.0 0.0 main Main 147 0 0.0 0.0 0.0 0.0 CAF GHC.Handle 103 6 0.0 0.0 0.0 0.0 CAF System.Posix.Internals 81 4 0.0 0.0 0.0 0.0 ------------------------------- Simon's: spellcheck +RTS -p -hr -H10m -K20m -RTS total time = 6.90 secs (345 ticks @ 20 ms) total alloc = 351,514,332 bytes (excludes profiling overheads) COST CENTRE MODULE %time %alloc main Main 93.0 93.6 hashPS Main 3.2 2.4 elemHashTable Main 2.0 0.1 addToHashTable Main 1.7 0.2 CAF Data.PackedString 0.0 3.6 individual inherited COST CENTRE MODULE no. entries %time %alloc %time %alloc MAIN MAIN 1 0 0.0 0.0 100.0 100.0 main Main 166 1 93.0 93.6 100.0 96.4 elemHashTable Main 171 38618 2.0 0.1 2.9 1.3 hashPS Main 172 38618 0.9 1.2 0.9 1.2 addToHashTable Main 168 38617 1.7 0.2 4.1 1.4 hashPS Main 169 38617 2.3 1.2 2.3 1.2 CAF Main 160 4 0.0 0.0 0.0 0.0 hashPS Main 170 0 0.0 0.0 0.0 0.0 main Main 167 0 0.0 0.0 0.0 0.0 CAF GHC.Handle 123 5 0.0 0.0 0.0 0.0 CAF System.Posix.Internals 101 4 0.0 0.0 0.0 0.0 CAF Data.PackedString 86 1 0.0 3.6 0.0 3.6 ----------------------------------------- ***************************************************************** Confidentiality Note: The information contained in this message, and any attachments, may contain confidential and/or privileged material. It is intended solely for the person(s) or entity to which it is addressed. Any review, retransmission, dissemination, or taking of any action in reliance upon this information by persons or entities other than the intended recipient(s) is prohibited. If you received this in error, please contact the sender and delete the material from any computer. *****************************************************************