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=0.6 required=5.0 tests=BAYES_00,TO_NO_BRKTS_FROM_MSSP autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,ba6120170d8e7faf X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-12-06 14:44:25 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!nntp-relay.ihug.net!ihug.co.nz!out.nntp.be!propagator-SanJose!in.nntp.be!news-in-sanjose!newsranger.com!www.newsranger.com!not-for-mail Newsgroups: comp.lang.ada From: Ted Dennison References: <3C0D536C.2E059EE8@computer.org> <0CdP7.48989$xS6.81382@www.newsranger.com> <3C0E5927.5657963A@baesystems.com> <3C0F7B36.52960668@computer.org> <3C0FE2DE.4BD905B9@computer.org> Subject: Re: Worst Case Execution Time Tool? Message-ID: X-Abuse-Info: When contacting newsranger.com regarding abuse please X-Abuse-Info: forward the entire news article including headers or X-Abuse-Info: else we will not be able to process your request X-Complaints-To: abuse@newsranger.com NNTP-Posting-Date: Thu, 06 Dec 2001 17:44:09 EST Organization: http://www.newsranger.com Date: Thu, 06 Dec 2001 22:44:09 GMT Xref: archiver1.google.com comp.lang.ada:17539 Date: 2001-12-06T22:44:09+00:00 List-Id: In article <3C0FE2DE.4BD905B9@computer.org>, StationSteve says... > >Ok, do you have time to educate me a little bit? >Why would a tool have to be "pretty darn smart" to measure the worst-case >execution time of a list traversal? What's the big driver in making such a >thing hard to do? Well, if its a dynamicly allocated list, then theoreticly the "worst case" would be the amount of time it takes to iterate through n/j items, where n is the amount of free memory you have after your program loads and j is the amount of bytes per list item. :-) In most cases there is a smaller "worst case" available, but you have to know a fair bit about the system to know what it is. For my real-time scheduler example, it could be that the list is implemented in an array with a hard limit of 40 items, and it wouldn't be too horribly dificult for a code analyzer to figure that out (although not trivial). On the other hand, it could be that the limit is the number of items listed in a configuration file that is read in at runtime. There's no possible way a tool could figure that out, because it isn't really set at all. --- T.E.D. homepage - http://www.telepath.com/dennison/Ted/TED.html No trees were killed in the sending of this message. However a large number of electrons were terribly inconvenienced.