Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder3.hal-mli.net!news.glorb.com!border3.nntp.dca.giganews.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local2.nntp.dca.giganews.com!nntp.earthlink.com!news.earthlink.com.POSTED!not-for-mail NNTP-Posting-Date: Sun, 03 Jul 2011 14:09:14 -0500 Date: Sun, 03 Jul 2011 12:09:21 -0700 From: Patricia Shanahan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.2.18) Gecko/20110616 Thunderbird/3.1.11 MIME-Version: 1.0 Newsgroups: comp.lang.java.programmer Subject: Re: baseline performance test using java ... References: <1309715588.716395@nntp.aceinnovative.com> In-Reply-To: <1309715588.716395@nntp.aceinnovative.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Lines: 64 X-Usenet-Provider: http://www.giganews.com NNTP-Posting-Host: 70.230.196.78 X-Trace: sv3-48eEfo0wQOBno4V2ZIMUuo917EzpkE+BGU2M3La1DCSLrTSW1wCngl4GF8Q0lEatmTCOo/TTeOt6BxD!lClOh9sXpZhxfkctrqZymGAoGRbQd1+nIeb603SsoyZ0ZkfVTjbYmugDVknjFOVKNkgOT1NQtklN!tHaIrV+4OKAgWQAuSqC4yHHY3PkdeS+aY2d8b1XrTZlw6A== X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 3959 Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:5836 On 7/3/2011 10:53 AM, lbrt chx _ gemale kom wrote: It would be better to reply to one article at a time, and do so in the same thread, rather than starting a new thread with a mixture of replies to different articles by different people. ... >> In general, benchmarking, like any experiment, only makes sense if >> you have some questions you want answered, and the measurements >> will answer those questions. I'm not at all clear what your >> questions are. > > The q is then. How much more (as a relative measure/percentage) does > my logical stack taxes the underlying (hw + sw) baseline? I still don't understand you. How do you define "taxes" and "the underlying (hw + sw) baseline"? > >> "Performance of an algorithm" is a non-trivial concept ... matter >> of analysis, not measurement. > > I am not sure if I got that one, but if we are talking here about the > implementation of an algo then surely can we for instance check how > much memory and time needs to run Dropping the material you replaced with "..." tends to change the meaning of the sentence. I do not think that all algorithm performance work is a matter of analysis. If you are interested in computer performance, and are not already familiar with the concept of computational complexity, I suggest looking into it. The Wikipedia page is a good starting point: http://en.wikipedia.org/wiki/Computational_complexity_theory You can measure how much memory and time an algorithm implementation needs to run in a specific program on some particular computer, with specific memory size, other work etc. When I first got seriously interested in computer performance, about 35 years ago, things were easier. A processor would do one thing, taking the same amount of time to do it regardless of memory etc., and then go on to the next thing. The time run a program was simply the sum of the times for each step. One could usefully estimate the time to run a program by counting the operations and adding their times. > >> Of course, one often needs to know how fast an algorithm will run >> for a specific problem size on a specific system. In that case, >> measurement is definitely the way to go. > > Well, yes. Now we are on the same page > >> With modern computers, any sort of isolated measurement can be >> misleading. There is so much caching and prediction that code can >> behave very differently in different contexts. > > Yes, Patricia. But give a little thinking to the type of measurement > I am talking about. Right on top of all system calls and under your > logical stack. There can and should be utilities to automate this I will happily think about it once I understand what you mean. Patricia