Re: does virtualizing all methods slow C++ down ?

From	Lynn McGuire <lmc@winsim.com>
Newsgroups	comp.lang.c++
Subject	Re: does virtualizing all methods slow C++ down ?
Date	2011-09-06 16:11 -0500
Organization	A noiseless patient Spider
Message-ID	<j462c0$vt9$1@dont-email.me> (permalink)
References	<j45hvi$6at$1@dont-email.me> <87ipp5zjb2.fsf@dpt-info.u-strasbg.fr> <j45rf0$d9e$1@dont-email.me> <j45tvf$f6c$1@speranza.aioe.org>

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On 9/6/2011 2:57 PM, jacob navia wrote:
> Le 06/09/11 21:13, Lynn McGuire a écrit :
>> Thanks, I had not thought about the direct calls just
>> directly binding to the proper method. I'll bet that
>> there are few direct calls in our code though as we
>> have many children classes.
>>
>> ObjPtr -> DataGroup -> GenGroup
>>
>> ObjPtr -> DataGroup -> NodeGroup -> StreamGroup
>>
>> are a couple of example lineages.
>>
>> Lynn
>
> This is completely ridiculous. An indirect call vs a direct call
> will cost you some pipeline turbulence and the cache may be flushed, really not a big deal.
>
> Have you MEASURED the slowdown? Is it significant in relationship
> to OTHER improvements in your code?
>
> Have you profiled your code to KNOW where it is spending 90% of the
> time?
>
> Before you answer THOSE questions, worrying about direc/indirect
> calls is WASTED time and effort.

I am not planning on changing our design, it works very well
and gets an amazing amount of work done in the amount of
code written.  After reading the "Generally, are the programs
written by C++ slower than written by C 10% ?" thread, I was
just wondering about the major difference between C and C++
in our code.  In the long and short runs, I would say that
the overhead is more than worth the automatic object method
lookups.  More than !

Thanks,
Lynn

Thread

does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 11:31 -0500
  Re: does virtualizing all methods slow C++ down ? Christopher <cpisz@austin.rr.com> - 2011-09-06 10:00 -0700
    Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 14:09 -0500
      Re: does virtualizing all methods slow C++ down ? Christopher <cpisz@austin.rr.com> - 2011-09-06 12:35 -0700
        Re: does virtualizing all methods slow C++ down ? "Kevin P. Fleming" <news@kpfleming.us> - 2011-09-06 16:41 -0500
      Re: does virtualizing all methods slow C++ down ? "Balog Pal" <pasa@lib.hu> - 2011-09-11 12:02 +0200
    Re: does virtualizing all methods slow C++ down ? "Thomas J. Gritzan" <phygon_antispam@gmx.de> - 2011-09-07 02:42 +0200
      Re: does virtualizing all methods slow C++ down ? Noah Roberts <roberts.noah@gmail.com> - 2011-09-07 07:39 -0700
        Re: does virtualizing all methods slow C++ down ? Richard Damon <news.x.richarddamon@xoxy.net> - 2011-09-07 11:46 -0400
    Re: does virtualizing all methods slow C++ down ? Nobody <nobody@nowhere.com> - 2011-09-07 01:45 +0100
  Re: does virtualizing all methods slow C++ down ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-09-06 19:12 +0200
    Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 14:13 -0500
      Re: does virtualizing all methods slow C++ down ? jacob navia <jacob@spamsink.net> - 2011-09-06 21:57 +0200
        Re: does virtualizing all methods slow C++ down ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-09-06 22:40 +0200
          Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 16:13 -0500
            Re: does virtualizing all methods slow C++ down ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-07 08:01 +0000
              Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-14 12:08 -0500
                Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-14 14:04 -0500
        Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 16:11 -0500
          Re: does virtualizing all methods slow C++ down ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-07 11:44 -0500
            Re: does virtualizing all methods slow C++ down ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-09-07 14:11 -0700
              Re: does virtualizing all methods slow C++ down ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-08 01:26 -0500
              Re: does virtualizing all methods slow C++ down ? Nobody <nobody@nowhere.com> - 2011-09-08 07:37 +0100
              Re: does virtualizing all methods slow C++ down ? zindorsky <nephi.allred@gmail.com> - 2011-09-09 10:20 -0700
                Re: does virtualizing all methods slow C++ down ? "Kevin P. Fleming" <news@kpfleming.us> - 2011-09-10 11:48 -0400
                Re: does virtualizing all methods slow C++ down ? Nobody <nobody@nowhere.com> - 2011-09-10 17:58 +0100
  Re: does virtualizing all methods slow C++ down ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 06:19 +0000
  Re: does virtualizing all methods slow C++ down ? Goran <goran.pusic@gmail.com> - 2011-09-06 23:52 -0700
    Re: does virtualizing all methods slow C++ down ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 07:57 +0000
      Re: does virtualizing all methods slow C++ down ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-07 10:39 +0000
      Re: does virtualizing all methods slow C++ down ? Goran <goran.pusic@gmail.com> - 2011-09-07 04:30 -0700
        Re: does virtualizing all methods slow C++ down ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 13:04 +0000
          Re: does virtualizing all methods slow C++ down ? Goran <goran.pusic@gmail.com> - 2011-09-07 06:18 -0700
  Re: does virtualizing all methods slow C++ down ? ld <laurent.deniau@gmail.com> - 2011-09-08 05:34 -0700

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