Comments on: begin…end as bottlenecks? http://delphitools.info/2009/03/25/beginend-as-bottlenecks/ SamplingProfiler, DWS and other Delphi tools Fri, 03 Feb 2012 09:15:27 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Eric http://delphitools.info/2009/03/25/beginend-as-bottlenecks/comment-page-1/#comment-72 Eric Thu, 26 Mar 2009 09:08:51 +0000 http://delphitools.info/?p=68#comment-72 Marco: const can improve the situation at the call point on types such as strings, records or interfaces, but for integers, it does nothing. The copy a shuffling isn't related to the index parameter but to the interface result. Jens: knowing what NOT to optimize is just as important as knowing what to optimize, that's what all the premature optimization thing is actually about: applying efforts where and only if it will matter. The whole point here is that with an instrumenting profiler and information at the procedure level (and likely inflated by an heisenbug effect), you would have been left trying to optimize the code that's in the procedure, code which isn't the source of the slowdown, thus wasting your time. As for the solution in this particular case, it's about taking care of the calls into that GetItem rather than the GetItem itself. Other begin-end bottleneck situations can have different solutions, which will be discussed later on :) Marco: const can improve the situation at the call point on types such as strings, records or interfaces, but for integers, it does nothing. The copy a shuffling isn’t related to the index parameter but to the interface result.

Jens: knowing what NOT to optimize is just as important as knowing what to optimize, that’s what all the premature optimization thing is actually about: applying efforts where and only if it will matter.
The whole point here is that with an instrumenting profiler and information at the procedure level (and likely inflated by an heisenbug effect), you would have been left trying to optimize the code that’s in the procedure, code which isn’t the source of the slowdown, thus wasting your time.
As for the solution in this particular case, it’s about taking care of the calls into that GetItem rather than the GetItem itself. Other begin-end bottleneck situations can have different solutions, which will be discussed later on :)

]]> By: Jens Borrisholt http://delphitools.info/2009/03/25/beginend-as-bottlenecks/comment-page-1/#comment-71 Jens Borrisholt Thu, 26 Mar 2009 08:20:49 +0000 http://delphitools.info/?p=68#comment-71 Exactly what was the point of this article ? You claim "Yes, those are the are the begin and end lines taking up more than 70% of the CPU time spent inside GetItem", but exactly what do you want us to do about it? You have writen an article with no points at all ... "Here is a problem" ... Fine and how to deal with it ? Exactly what was the point of this article ? You claim “Yes, those are the are the begin and end lines taking up more than 70% of the CPU time spent inside GetItem”, but exactly what do you want us to do about it?

You have writen an article with no points at all …

“Here is a problem” … Fine and how to deal with it ?

]]> By: Marco Sangali http://delphitools.info/2009/03/25/beginend-as-bottlenecks/comment-page-1/#comment-64 Marco Sangali Wed, 25 Mar 2009 14:05:39 +0000 http://delphitools.info/?p=68#comment-64 Wouldn't defining index as const improve the situation, as there will be no need of a local copy of the value? Best Regards Wouldn’t defining index as const improve the situation, as there will be no need of a local copy of the value?
Best Regards

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