The total execution time is startup_time + count * iteration_time. For numbers like 10..10000 the loop time is negligible compared to reading the interpreter from disk, parsing script etc.

You can eliminate the startup time (assuming it's constant) by running several different big (10**6+) loops, then plotting time against count:

bash$ for i in `seq 10`; do echo $i; time perl -e 'for($i=0;$i<='$i'*1
+000000 ;$i++){}'; done 
1

real    0m0.055s
user    0m0.048s
sys    0m0.000s
2

real    0m0.051s
user    0m0.048s
sys    0m0.000s
3

real    0m0.074s
user    0m0.068s
sys    0m0.000s
4

real    0m0.099s
user    0m0.088s
sys    0m0.004s
5

real    0m0.124s
user    0m0.116s
sys    0m0.000s
6

real    0m0.146s
user    0m0.140s
sys    0m0.000s
7

real    0m0.166s
user    0m0.164s
sys    0m0.000s
8

real    0m0.197s
user    0m0.184s
sys    0m0.000s
9

real    0m0.217s
user    0m0.204s
sys    0m0.004s
10

real    0m0.235s
user    0m0.232s
sys    0m0.000s

bash$ for i in `seq 10`; do echo $i; time php -r 'for($i=0;$i<='$i'*10
+00000 ;$i++){}'; done 
1

real    0m0.034s
user    0m0.020s
sys    0m0.012s
2

real    0m0.036s
user    0m0.028s
sys    0m0.000s
3

real    0m0.035s
user    0m0.032s
sys    0m0.000s
4

real    0m0.040s
user    0m0.036s
sys    0m0.000s
5

real    0m0.048s
user    0m0.040s
sys    0m0.004s
6

real    0m0.055s
user    0m0.052s
sys    0m0.000s
7

real    0m0.065s
user    0m0.060s
sys    0m0.000s
8

real    0m0.071s
user    0m0.068s
sys    0m0.000s
9

real    0m0.080s
user    0m0.076s
sys    0m0.000s
10

real    0m0.087s
user    0m0.084s
sys    0m0.000s

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What surprises me here is that PHP is much faster than Perl.

In reply to Re: perl process slower and slower when loop number increase by Dallaylaen
in thread perl process slower and slower when loop number increase by Anonymous Monk

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