From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,703c4f68db81387d X-Google-Thread: 115aec,703c4f68db81387d X-Google-Thread: f43e6,703c4f68db81387d X-Google-Attributes: gid103376,gid115aec,gidf43e6,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!postnews.google.com!f14g2000cwb.googlegroups.com!not-for-mail From: "fabio de francesco" Newsgroups: comp.lang.ada,comp.realtime,comp.software-eng Subject: Re: Teaching new tricks to an old dog (C++ -->Ada) Date: 10 Mar 2005 20:20:19 -0800 Organization: http://groups.google.com Message-ID: <1110514819.068611.218200@f14g2000cwb.googlegroups.com> References: <4229bad9$0$1019$afc38c87@news.optusnet.com.au> <1110032222.447846.167060@g14g2000cwa.googlegroups.com> <871xau9nlh.fsf@insalien.org> <3SjWd.103128$Vf.3969241@news000.worldonline.dk> <87r7iu85lf.fsf@insalien.org> <1110052142.832650@athnrd02> <1110284070.410136.205090@o13g2000cwo.googlegroups.com> <395uqaF5rhu2mU1@individual.net> <112rs0bdr2aftdf@corp.supernews.com> <1inxxr988rxgg$.1w9dedak41k89.dlg@40tude.net> <112s1r0rf0o8nca@corp.supernews.com> <112sonip5v4dca6@corp.supernews.com> <112t3de6fu04f38@corp.supernews.com> <112u7undo5h2q0a@corp.supernews.com> <1110513620.359357.314400@l41g2000cwc.googlegroups.com> NNTP-Posting-Host: 80.181.51.48 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1110514822 2876 127.0.0.1 (11 Mar 2005 04:20:22 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Fri, 11 Mar 2005 04:20:22 +0000 (UTC) In-Reply-To: <1110513620.359357.314400@l41g2000cwc.googlegroups.com> User-Agent: G2/0.2 Complaints-To: groups-abuse@google.com Injection-Info: f14g2000cwb.googlegroups.com; posting-host=80.181.51.48; posting-account=Lp02jQ0AAABMd3TAghNf0TM2YBZqD_JE Xref: g2news1.google.com comp.lang.ada:9088 comp.realtime:1235 comp.software-eng:4803 Date: 2005-03-10T20:20:19-08:00 List-Id: fabio de francesco wrote: > Pascal Obry wrote: > > > I get: > > > > $ time matrix 100 > > 270165 1061760 1453695 1856025 > > > > real 0m0.033s > > user 0m0.010s > > sys 0m0.020s > > > > $ time c_matrix 100 > > 270165 1061760 1453695 1856025 > > > > real 0m0.033s > > user 0m0.010s > > sys 0m0.010s > > I think you made a big mistake by thinking you had equal results for > matrix and c_matrix execution times. Don't look at "real" value, > because it mostly depends on how much your computer is loaded while > executing programs your're timing. That is the "real" time difference > between start and end of program that is spent also in executing other > tasks by your computer. You should only look at "user" and "sys" times > that represent how much CPU time is spent for the particular program. > "user" is time spent while executing in user address space, while "sys" > is time spent while executing in kernel space on behalf of the program. > > Furthermore you'd better take times after a second execution in order > to have both programs already in memory, so times are not affected by > seeking disks and some othr operations. Even doing so you won't get reliable results because "user" and "sys" times can be a lot different from an execution to the other due to context switches that can change in number. What I want to say is that here too times depend on computer load, what is in cache after returning from the latest context switch, hardware interrupts and a lot of other different variables. Maybe you can get a quite reliable statistics over a hundreds of executions, better if the two programs are simulaneously executed with some kind of shell script. Nothing scientific in these methods, I'm afraid. Ciao, fabio de francesco > > Ciao, > > fabio de francesco