On Tue, Feb 16, 2010 at 3:45 PM, Jean-Marie Gaillourdet wrote: Hi, 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 list, the first k elements and hands them to the caller. Caller Daniel Fischer wrote:
the beginning of
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? I believe it's the latter. I think the RTS uses a periodic SIGALRM to figure
out which function is currently executing and to record that in the profile.
Simon Marlow would know.