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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>That’s a much smaller difference than I’d expect. I can’t
explain why.<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>One reason may be that you probably didn’t recompile all the
libraries with –O0, and some (but far from all) nofib programs spend a lot of
time in library code.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Simon<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> cvs-ghc-bounces@haskell.org
[mailto:cvs-ghc-bounces@haskell.org] <b>On Behalf Of </b>David Peixotto<br>
<b>Sent:</b> 09 October 2009 05:01<br>
<b>To:</b> cvs-ghc@haskell.org<br>
<b>Subject:</b> nofib benchmarks for measuring the effects of compiler optimizations<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Hi,<o:p></o:p></p>
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<p class=MsoNormal>I'm interested in looking at the effects on performance of
various compiler optimizations in GHC. I ran the nofib benchmarks against the
stable branch to get a feel for some very simple results. In my
measurements I only saw a maximum of 2.8% difference in runtime when
using -O0 and -O2 flags. Also, it looks like only 5 of the benchmarks had
a running time of more than 1 second. Do these look like results you would
expect to see? <o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>I am setting the compilation flags in $(GHC_TOP)/mk/build.mk
by<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>SRC_HC_OPTS = <o:p></o:p></p>
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<p class=MsoNormal>NoFibHcOpts = -H64m -O0 # or -O2<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>and running the benchmarks by using make. It looks like the
flags are getting picked up correctly judging by the output generated when
running the benchmarks. <o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>Would you say that the nofib benchmarks are the best
available for measuring the effectiveness of compiler optimizations, or is
there a better benchmarking suite for that purpose? Thanks!<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal>-David<o:p></o:p></p>
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<p class=MsoNormal><o:p> </o:p></p>
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