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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><div><p class=MsoNormal>On 1 March 2013 16:31, David Tweed <<a href="mailto:David.Tweed@arm.com" target="_blank">David.Tweed@arm.com</a>> wrote:<o:p></o:p></p><div><div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>benchmarking is a science in the sense that once a user has decided what goals/properties they consider important, then one set of statistical procedure can be determined to be better at achieving those goals than another.</span><o:p></o:p></p></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'>| </span>When you know the question, the answer is obvious. The art is knowing which question is more important... ;)<o:p></o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>So, my recent personal experience (and admittedly this has been "microbenchmarking" in that I was looking for detecting small differences due to different code generation strategies within an automated optimization loop) is that the kind of data you get looks to have a "dense" distribution from the starting point up to some level, with a few significantly bigger outliers. Reanalysing one set of data for various code options, the arithmetic mean varies from essentially the same as the median to up to 10% (and in one case 15% larger). Personally I'm reasonably convinced that the using a trimmed deviation around a median is giving a better estimate of the "inherently variable program execution" random variable, but that's just in the context of the kind of stuff I've been doing.<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'>Cheers,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Dave<o:p></o:p></span></p></div></div></div></div></div></body></html>