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Re: C++ FQA [message #12671 is a reply to message #12665]

Mon, 12 November 2007 21:39

cbpporter
Messages: 1428
Registered: September 2007

Ultimate Contributor

Quote:

BTW, I did only that single benchmark D vs U++ - U++ was about 2x faster, but what was really shocking is that D consumed 5 times as much memory....

As said before, D has a known performance problem with built in hash maps. I guess the developers are more concerned with the shape of the language and haven't had time to optimize such details yet.

As for the memory consumption, I am not surprised at all. Mark and sweep abandons traditional memory paradigms as allocation when you need and freeing again when you are done with the object. As much as you can optimize these algorithms, allocation and memory freeing are very time consuming operations (relatively speaking of course). In mark and sweep, allocation consists of an if to see if there is enough space. If not, a huge block is allocated. If there is enough space, a simple pointer incrementation is performed. Very fast. You continue to allocate and only do time costly deallocations when you are out of physical memory or have reached a certain threshold. Another advantage is zero memory fragmentation is the mark-and-sweeper is also a moving-compactor. And if you make it generational too, you can really optimize it. So in theory, GC programs should run a lot faster. Memory is cheap, and if with 1-2 GB of memory extra you can gain sufficient extra speed, I think GC will continue to get more and more popular. But this is only theory, and that's why I'm interested in some scientifically sane benchmarks.

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[Message index]

		C++ FQA By: unodgs on Tue, 06 November 2007 23:27
		Re: C++ FQA By: Mindtraveller on Wed, 07 November 2007 00:41
		Re: C++ FQA By: unodgs on Wed, 07 November 2007 10:40
		Re: C++ FQA By: cbpporter on Wed, 07 November 2007 11:33
		Re: C++ FQA By: unodgs on Wed, 07 November 2007 13:15
		Re: C++ FQA By: Mindtraveller on Wed, 07 November 2007 14:03
		Re: C++ FQA By: cbpporter on Wed, 07 November 2007 14:57
		Re: C++ FQA By: Mindtraveller on Wed, 07 November 2007 18:02
		Re: C++ FQA By: cbpporter on Wed, 07 November 2007 19:30
		Re: C++ FQA By: Mindtraveller on Thu, 08 November 2007 00:13
		Re: C++ FQA By: mirek on Thu, 08 November 2007 05:34
		Re: C++ FQA By: Zardos on Thu, 08 November 2007 13:33
		Re: C++ FQA By: mirek on Thu, 08 November 2007 19:25
		Re: C++ FQA By: mdelfede on Thu, 08 November 2007 23:39
		Re: C++ FQA By: mirek on Fri, 09 November 2007 08:51
		Re: C++ FQA By: mdelfede on Fri, 09 November 2007 13:41
		Re: C++ FQA By: mirek on Fri, 09 November 2007 14:48
		Re: C++ FQA By: mdelfede on Fri, 09 November 2007 15:52
		Re: C++ FQA By: waxblood on Fri, 09 November 2007 17:07
		Re: C++ FQA By: mdelfede on Fri, 09 November 2007 19:51
		Re: C++ FQA By: mirek on Sat, 10 November 2007 15:14
		Re: C++ FQA By: mdelfede on Sat, 10 November 2007 17:06
		Re: C++ FQA By: cbpporter on Sat, 10 November 2007 17:31
		Re: C++ FQA By: mirek on Sat, 10 November 2007 17:54
		Re: C++ FQA By: mdelfede on Sat, 10 November 2007 23:57
		Re: C++ FQA By: mirek on Sun, 11 November 2007 09:54
		Re: C++ FQA By: mdelfede on Sun, 11 November 2007 11:25
		Re: C++ FQA By: Zardos on Tue, 13 November 2007 01:56
		Re: C++ FQA By: mirek on Tue, 13 November 2007 09:25
		Re: C++ FQA By: cbpporter on Tue, 13 November 2007 10:14
		Re: C++ FQA By: mirek on Tue, 13 November 2007 10:52
		Re: C++ FQA By: mirek on Thu, 22 November 2007 05:43
		Re: C++ FQA By: mdelfede on Sun, 11 November 2007 11:36
		Re: C++ FQA By: Mindtraveller on Sun, 11 November 2007 18:22
		Re: C++ FQA By: mdelfede on Sun, 11 November 2007 18:52
		Re: C++ FQA By: Mindtraveller on Mon, 12 November 2007 00:58
		Re: C++ FQA By: mirek on Mon, 12 November 2007 09:46
		Re: C++ FQA By: mdelfede on Mon, 12 November 2007 10:19
		Re: C++ FQA By: cbpporter on Mon, 12 November 2007 10:28
		Re: C++ FQA By: mdelfede on Mon, 12 November 2007 11:43
		Re: C++ FQA By: Mindtraveller on Mon, 12 November 2007 15:54
		Re: C++ FQA By: mdelfede on Mon, 12 November 2007 16:47
		Re: C++ FQA By: cbpporter on Mon, 12 November 2007 16:51
		Re: C++ FQA By: mirek on Mon, 12 November 2007 20:15
		Re: C++ FQA By: mirek on Mon, 12 November 2007 20:21
		Re: C++ FQA By: cbpporter on Mon, 12 November 2007 21:39
		Re: C++ FQA By: mirek on Mon, 12 November 2007 22:43
		Re: C++ FQA By: cbpporter on Mon, 12 November 2007 23:22
		Re: C++ FQA By: mirek on Mon, 12 November 2007 23:34
		Re: C++ FQA By: mdelfede on Mon, 12 November 2007 23:33
		Re: C++ FQA By: exolon on Tue, 13 November 2007 17:30
		Re: C++ FQA By: mdelfede on Tue, 13 November 2007 18:24
		Re: C++ FQA By: exolon on Tue, 13 November 2007 18:58
		Re: C++ FQA By: Mindtraveller on Fri, 16 November 2007 00:43
		Re: C++ FQA By: mirek on Fri, 16 November 2007 11:59
		Re: C++ FQA By: waxblood on Fri, 16 November 2007 16:24
		Re: C++ FQA By: mdelfede on Fri, 16 November 2007 16:37
		Re: C++ FQA By: mirek on Sat, 17 November 2007 10:04
		Re: C++ FQA By: mirek on Sat, 10 November 2007 15:22
		Re: C++ FQA By: mdelfede on Sat, 10 November 2007 16:58
		Re: C++ FQA By: mirek on Thu, 08 November 2007 05:25
		Re: C++ FQA By: mirek on Wed, 07 November 2007 15:14
		Re: C++ FQA By: mdelfede on Wed, 07 November 2007 15:39
		Re: C++ FQA By: exolon on Mon, 12 November 2007 13:09
		Re: C++ FQA By: mr_ped on Wed, 07 November 2007 17:05
		Re: C++ FQA By: tvanriper on Fri, 09 November 2007 12:56
		Re: C++ FQA By: mr_ped on Sat, 10 November 2007 22:26
		Re: C++ FQA By: mirek on Sat, 10 November 2007 22:35
		Re: C++ FQA By: Mindtraveller on Tue, 13 November 2007 02:41
		Re: C++ FQA By: Mindtraveller on Thu, 27 December 2007 14:47

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