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SetBatchLines, 20ms is 50% faster than 15ms??

 
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Ginger
Guest
PostPosted: Tue May 13, 2008 9:10 pm    Post subject: SetBatchLines, 20ms is 50% faster than 15ms?? Reply with quote
Code:

x := 20

a := A_TickCount
SetBatchLines, %x%ms
Loop, 1000
{
   Loop, 10000
   {
      h++
   }
}
b := A_TickCount
MsgBox, % b - a


SetBatchLines, 20ms is 50% faster than SetBatchLines 15ms. Why is it like that?

As I understand it SetBatchLines is how long the script should run before sleeping for 10ms. If that would have been the case then 20ms should be running at 20/(20+10)=66% speed while 15ms should be running at 15/(15+10)=60% speed.

In other words 20ms should be running (66-60)/60=10% faster than 15ms, not 50% faster.

Why is it 50% and not 10%
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Ginger
Guest
PostPosted: Tue May 13, 2008 9:30 pm    Post subject: Reply with quote
Here is a better illustration
Code:

Loop, 20
{
   x := 5+A_Index-1
   a := A_TickCount
   SetBatchLines, %x%ms
   Loop, 1000
   {
      Loop, 1000
      {
         h=0
         h++
         h--
      }
   }
   b := A_TickCount
   out .= "SetBatchLines, " x "ms " "`t" b-a "ms" "`r`n"
}
MsgBox, % out


The results are surprising to me:
Code:

SetBatchLines, 5ms    1593ms
SetBatchLines, 6ms    1625ms
SetBatchLines, 7ms    1625ms
SetBatchLines, 8ms    1594ms
SetBatchLines, 9ms    1625ms
SetBatchLines, 10ms    1625ms
SetBatchLines, 11ms    1594ms
SetBatchLines, 12ms    1562ms
SetBatchLines, 13ms    1594ms
SetBatchLines, 14ms    1594ms
SetBatchLines, 15ms    1594ms
SetBatchLines, 16ms    1187ms
SetBatchLines, 17ms    1078ms
SetBatchLines, 18ms    1078ms
SetBatchLines, 19ms    1079ms
SetBatchLines, 20ms    1078ms
SetBatchLines, 21ms    1078ms
SetBatchLines, 22ms    1078ms
SetBatchLines, 23ms    1078ms
SetBatchLines, 24ms    1109ms
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Oberon



Joined: 18 Feb 2008
Posts: 458
PostPosted: Tue May 13, 2008 9:49 pm    Post subject: Reply with quote
The system sleep resolution usually varies between 10ms and 20ms so benchmarking micro-delays is too volatile for reliable results. This is briefly mentioned in the documentation. Sleep is the antithesis of performance lolz.
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Ginger
Guest
PostPosted: Tue May 13, 2008 11:58 pm    Post subject: Reply with quote
I got the same result running the test several times. Jumps between 15ms, 16ms and 17ms. Other ms changes doing nothing.
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Giner
Guest
PostPosted: Wed May 14, 2008 10:43 pm    Post subject: Reply with quote
Any more comments? Is this the way it is supposed to be? If I want to make my script 10%, 20%, or 30% slower but not 50% slower, is there any work around?

Anyone? engunner?
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