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Adding a function timing analysis module.
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%% @copyright 2011 Geoff Cant | ||
%% @author Geoff Cant <gcant@erlang.geek.nz> | ||
%% @version {@date} {@time} | ||
%% @doc Function call timing analysis. Parts lifted from hipe_timer.erl (thanks OTP) | ||
%% @end | ||
-module(funalysis). | ||
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-export([advanced/2, | ||
par_advanced/3]). | ||
-export([par_proc_iterations/2, | ||
analyse/2]). | ||
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t(F) -> | ||
NullTime = empty_time(), | ||
{Time, _} = timer:tc(F, []), | ||
erlang:max(Time - NullTime, 0). | ||
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% -spec empty_time() -> microseconds(). | ||
empty_time() -> | ||
{Time, _} = timer:tc(fun () -> ok end, []), | ||
Time. | ||
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advanced(_Fun, I) when I < 2 -> false; | ||
advanced(Fun, Iterations) -> | ||
Measurements = [t(Fun) || _ <- lists:seq(1, Iterations)], | ||
analyse(Measurements, Iterations). | ||
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par_advanced(Fun, Procs, Iterations) when Iterations > Procs, Procs > 0 -> | ||
Master = self(), | ||
Ref = make_ref(), | ||
Pids = [ spawn( fun () -> timing_loop(Master, Ref, Fun, ProcIters ) end ) | ||
|| ProcIters <- par_proc_iterations(Procs, Iterations) ], | ||
Measurements = lists:flatmap( fun (Pid) -> | ||
receive | ||
{Pid, Ref, M} -> M | ||
end | ||
end, | ||
Pids), | ||
analyse(Measurements, Iterations). | ||
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par_proc_iterations(Procs, Iterations) -> | ||
Rem = (Iterations rem Procs), | ||
[ case N =< Rem of | ||
true -> (Iterations div Procs) + 1; | ||
false -> (Iterations div Procs) | ||
end | ||
|| N <- lists:seq(1, Procs) ]. | ||
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timing_loop(Master, Ref, Fun, ProcIters) -> | ||
Master ! {self(), Ref, [t(Fun) || _ <- lists:seq(1, ProcIters) ]}, | ||
exit(normal). | ||
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analyse(Measurements, Iterations) -> | ||
Wallclock = Measurements, | ||
WMin = lists:min(Wallclock), | ||
WMax = lists:max(Wallclock), | ||
WMean = mean(Wallclock), | ||
WMedian = median(Wallclock), | ||
WVariance = variance(Wallclock), | ||
WStddev = stddev(Wallclock), | ||
WVarCoff = 100 * WStddev / WMean, | ||
WSum = lists:sum(Wallclock), | ||
[{wallclock,[{min, WMin}, | ||
{max, WMax}, | ||
{mean, WMean}, | ||
{median, WMedian}, | ||
{variance, WVariance}, | ||
{stdev, WStddev}, | ||
{varcoff, WVarCoff}, | ||
{sum, WSum}, | ||
{values, Wallclock}]}, | ||
{iterations, Iterations}]. | ||
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split(M) -> | ||
split(M, [], []). | ||
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split([{W,R}|More], AccW, AccR) -> | ||
split(More, [W|AccW], [R|AccR]); | ||
split([], AccW, AccR) -> | ||
{AccW, AccR}. | ||
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mean(L) -> | ||
mean(L, 0, 0). | ||
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mean([V|Vs], No, Sum) -> | ||
mean(Vs, No+1, Sum+V); | ||
mean([], No, Sum) when No > 0 -> | ||
Sum/No; | ||
mean([], _No, _Sum) -> | ||
exit(empty_list). | ||
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median(L) -> | ||
S = length(L), | ||
SL = lists:sort(L), | ||
case even(S) of | ||
true -> | ||
(lists:nth((S div 2), SL) + lists:nth((S div 2) + 1, SL)) / 2; | ||
false -> | ||
lists:nth((S div 2), SL) | ||
end. | ||
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even(S) -> | ||
(S band 1) =:= 0. | ||
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%% diffs(L, V) -> | ||
%% [X - V || X <- L]. | ||
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square_diffs(L, V) -> | ||
[(X - V) * (X - V) || X <- L]. | ||
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variance(L) -> | ||
Mean = mean(L), | ||
N = length(L), | ||
if N > 1 -> | ||
lists:sum(square_diffs(L,Mean)) / (N-1); | ||
true -> exit('too few values') | ||
end. | ||
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stddev(L) -> | ||
math:sqrt(variance(L)). |