[Issue 4447] order of functions greatly affects execution time

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4447

RazvanN  changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 CC||razvan.nitu1...@gmail.com
 Resolution|--- |INVALID

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[Issue 4447] order of functions greatly affects execution time

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4447

Iain Buclaw  changed:

   What|Removed |Added

   Priority|P2  |P3

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[Issue 4447] order of functions greatly affects execution time

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4447

Vladimir Panteleev  changed:

   What|Removed |Added

   Keywords||performance

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[Issue 4447] order of functions greatly affects execution time

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4447

Andrei Alexandrescu  changed:

   What|Removed |Added

   Keywords||bootcamp
 CC||and...@erdani.com

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[Issue 4447] order of functions greatly affects execution time

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4447

Andrei Alexandrescu and...@erdani.com changed:

   What|Removed |Added

Version|D1  D2 |D2

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[Issue 4447] order of functions greatly affects execution time

[d-bugmail]

http://d.puremagic.com/issues/show_bug.cgi?id=4447


Heywood Floyd soul...@gmail.com changed:

   What|Removed |Added

 CC||soul...@gmail.com


--- Comment #1 from Heywood Floyd soul...@gmail.com 2010-07-12 08:58:39 PDT 
---
// - - 8 - -
  version(one)
  {
fooManual(a, b);
fooCompiler(a, b);
fooManual(a, b); 
fooCompiler(a, b);
fooManual(a, b); 
fooCompiler(a, b);
 }
 version(two)
  {
fooCompiler(a, b);
fooManual(a, b); 
fooCompiler(a, b);
fooManual(a, b); 
fooCompiler(a, b);
fooManual(a, b);
 }
// - - 8 - -

$ dmd -inline -O -release -version=one -run odd
manual:   d = 32.00, B578time: 126120
compiler: d = 32.00, B578time: 8200
manual:   d = 32.00, B578time: 5920
compiler: d = 32.00, B578time: 5960
manual:   d = 32.00, B578time: 5690
compiler: d = 32.00, B578time: 5620
$ dmd -inline -O -release -version=two -run odd
compiler: d = 32.00, B578time: 130200
manual:   d = 32.00, B578time: 8140
compiler: d = 32.00, B578time: 5800
manual:   d = 32.00, B578time: 5730
compiler: d = 32.00, B578time: 5590
manual:   d = 32.00, B578time: 5600
$ _

I can't see that the order of the functions have any impact, rather, the first
couple of 100-thousand CPU ticks the program is not at 100% of its potential
performance. This could be anything, maybe the OS must set some things up for
the first write to stdout, or, the D runtime must do some things, like
expanding the heap for the first allocation etc? I've no idea. Just guessing.

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