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Re: CLOCKS_PER_SEC

From BartC <bc@freeuk.com>
Newsgroups comp.lang.c
Subject Re: CLOCKS_PER_SEC
Date 2016-10-14 18:18 +0100
Organization A noiseless patient Spider
Message-ID <ntr40k$jjd$1@dont-email.me> (permalink)
References <nto3cm$ps$1@dont-email.me> <20161014162129.223274fe7ba3d5b06850f0e1@g{oogle}mail.com> <lnwphbhran.fsf@kst-u.example.com> <ntqv7f$df$1@jstuckle.eternal-september.org> <20161014195348.b58ccefe064bded596425856@g{oogle}mail.com>

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On 14/10/2016 17:53, Anton Shepelev wrote:
> Jerry Stuckle:

>> And don't forget -- modern PC's can adjust CPU fre-
>> quency on the fly.  What you get in one calculation
>> may  be  much different when repeated.  Things like
>> instruction prefetch, bus  contention  on  multiple
>> core CPUs can also affect results, although usually
>> not as significantly.
>
> Thanks, I now see  that  I  was  wrong.   My  method
> worked  in  MS-DOS  but  will not on modern hardware
> running modern OSes.

You also have to persuade a compiler not to completely optimise out what 
it thinks is a pointless loop.

-- 
Bartc

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Thread

CLOCKS_PER_SEC BartC <bc@freeuk.com> - 2016-10-13 14:49 +0100
  Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-13 08:57 -0700
    Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-13 09:07 -0700
      Re: CLOCKS_PER_SEC BartC <bc@freeuk.com> - 2016-10-13 23:18 +0100
        Re: CLOCKS_PER_SEC BartC <bc@freeuk.com> - 2016-10-13 23:30 +0100
          Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-13 16:27 -0700
            Re: CLOCKS_PER_SEC raltbos@xs4all.nl (Richard Bos) - 2016-10-16 10:02 +0000
              Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-16 11:32 -0700
    Re: CLOCKS_PER_SEC Lowell Gilbert <lgusenet@be-well.ilk.org> - 2016-10-13 12:19 -0400
      Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-13 11:29 -0700
        Re: CLOCKS_PER_SEC Lowell Gilbert <lgusenet@be-well.ilk.org> - 2016-10-13 14:39 -0400
          Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-13 12:03 -0700
        Re: CLOCKS_PER_SEC supercat@casperkitty.com - 2016-10-14 07:47 -0700
  Re: CLOCKS_PER_SEC Anton Shepelev <anton.txt@g{oogle}mail.com> - 2016-10-14 16:21 +0300
    Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-14 08:41 -0700
      Re: CLOCKS_PER_SEC Anton Shepelev <anton.txt@g{oogle}mail.com> - 2016-10-14 18:56 +0300
        Re: CLOCKS_PER_SEC Barry Schwarz <schwarzb@dqel.com> - 2016-10-14 09:49 -0700
        Re: CLOCKS_PER_SEC Keith Thompson <kst-u@mib.org> - 2016-10-14 11:14 -0700
          Re: CLOCKS_PER_SEC supercat@casperkitty.com - 2016-10-14 11:32 -0700
      Re: CLOCKS_PER_SEC Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-14 11:56 -0400
        Re: CLOCKS_PER_SEC Anton Shepelev <anton.txt@g{oogle}mail.com> - 2016-10-14 19:53 +0300
          Re: CLOCKS_PER_SEC supercat@casperkitty.com - 2016-10-14 09:57 -0700
          Re: CLOCKS_PER_SEC BartC <bc@freeuk.com> - 2016-10-14 18:18 +0100
        Re: CLOCKS_PER_SEC Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-16 02:55 -0700

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