Hi, Daniel Fischer wrote:
total alloc = 165,728 bytes (excludes profiling overheads)
COST CENTRE MODULE %time %alloc
CAF GHC.Handle 0.0 10.7 CAF Text.Read.Lex 0.0 2.1 CAF GHC.Read 0.0 1.2 square Main 0.0 2.8 solve Main 0.0 1.3 show_aVx Main 0.0 3.7 readsPrec_aYF Main 0.0 60.6 main Main 0.0 9.6 genNums Main 0.0 5.0 cell Main 0.0 1.2
individual inherited COST CENTRE MODULE no. entries %time %alloc %time %alloc
MAIN MAIN 1 0 0.0 0.3 0.0 100.0 main Main 186 1 0.0 9.6 0.0 85.6 show_aVx Main 196 2 0.0 3.7 0.0 3.7 cell Main 197 16 0.0 0.0 0.0 0.0 solve Main 188 5 0.0 1.3 0.0 11.8 genNums Main 189 8 0.0 5.0 0.0 10.4 square Main 194 88 0.0 2.8 0.0 3.2 cell Main 195 16 0.0 0.4 0.0 0.4 col Main 192 4 0.0 0.7 0.0 1.1 cell Main 193 16 0.0 0.4 0.0 0.4 row Main 190 4 0.0 0.7 0.0 1.1 cell Main 191 16 0.0 0.4 0.0 0.4 readsPrec_aYF Main 187 3 0.0 60.6 0.0 60.6 CAF GHC.Read 151 1 0.0 1.2 0.0 1.2 CAF Text.Read.Lex 144 8 0.0 2.1 0.0 2.1 CAF GHC.Handle 128 4 0.0 10.7 0.0 10.7 CAF GHC.Conc 127 1 0.0 0.0 0.0 0.0
Does the column 'entries' represent the number of times the function was called?
Number of times it was 'entered', not quite the same as the number of times it was called. I think (Warning: speculation ahead, I don't *know* how the profiles are generated) it's thus: Say you call a function returning a list. One call, first entry. It finds the beginning of the list, the first k elements and hands them to the caller. Caller processes these, asks "can I have more, or was that it?". Same call, second entry: f looks for more, finds the next m elements, hands them to caller. Caller processes. Repeat until whatever happens first, caller doesn't ask whether there's more or callee finds there's nothing more (or hits bottom).
Warning: speculation ahead, but is based on my knowledge on other profilers. Many profilers work statistically, they interrupt a program at more less random (or equal) intervals and inspect the stack, whick is of course quite difficult in Haskell as far as I understand it. I have interpreted the entries column as an indication for the amount of "profile interrupts" which happened when a function f was on top of the stack, whatever that means in Haskell. The manual of GHC 6.10.4, chapter 5 states:
The actual meaning of the various columns in the output is:
entries
The number of times this particular point in the call graph was entered.
So for me the question remains open, is "entries" a precisely counted value or a statistically determined one? Best regards, Jean