### Re^3: perl process slower and slower when loop number increase

by dave_the_m (Monsignor)
 on Jan 22, 2018 at 16:39 UTC ( #1207683=note: print w/replies, xml ) Need Help??

Ok lets step back a bit. why are you surprised that php does better than perl in some benchmarks?

Dave.

• Comment on Re^3: perl process slower and slower when loop number increase

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Re^4: perl process slower and slower when loop number increase
by Anonymous Monk on Jan 22, 2018 at 17:13 UTC

no, it's not about PHP or perl vs XXXX

it's about how to make perl loop faster, and back to first post,I think there is "magic setting" to increase this limitation

see image provide by choroba above

You are misinterpreting the graph: note that it has a logarithmic x-axis. Everything in this thread has shown that (subject to measurement noise), the execution time of this perl code:
```for (\$i = 0; \$i < N, \$i++) {}
increases linearly with N.

For the purpose of focusing the discussion, do you (1) dispute that the relationship between time and N is linear, or (2) agree that it is linear, but wish it to be sub-linear?

Dave.

If the Anonymous OP is confused by the logarithmic x-axis: for an equal distance along the x-axis, the x-value goes up by a constant factor. (So if the ticks were 1cm apart, and 10 is on the far left, then 1cm to the right of 10 is 100, and 1cm to the right of 100 is 1000: ie, every factor of 10 gets an equal amount of space on the x-axis). gnuplot labels the ticks, so it was unambiguous; however, not everyone has experience looking at a graph with a logarithmic x-axis, so the curve the OP saw might not be immediately identified in the OP's mind as linear.

If the OP wants a graph with a linear x-axis, then edit choroba's code by changing the following lines in sub plot { ...: change the lines here:

```    print {\$gp} join "\n", 'set term png;',
'set output "measure.png";',
'set key left;',
'set logscale x;';
into the lines here:
```    print {\$gp} join "\n", 'set term png;',
'set output "measure.png";',
'set key left;';
#                      'set logscale x;';

When I plotted with a linear x-axis, the curve for perl is almost perfectly straight -- I think that might communicate the idea to the OP with more clarity.

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